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the food particle forming food vacuole. Inside the food vacuole, complex substances are broken down into simpler ones. Then diffuse into the cytoplasm. The remaining undigested material is moved to the surface of the cell and thrown out. In Paramoecium [fig-9(b)], which is also a unicellular organism the cell has a definite shape. Food is taken in at a specific spot. Food is moved to the spot by the movement of cilia which covers the entire surface of the cell, where the food is ingested (cytostome). 12 X Class Nutrition - Food supplying system Parasitic nutrition in Cuscuta Dodder (genus Cuscuta) is a leafless, twining, parasitic plant belongs to morning glory family (Convolvulaceae). The genus contains about 170 twining species that are widely distributed throughout the temperate and tropical regions of the world. The dodder contains no chlorophyll (Cuscuta reflexa has been found to have very small amount of chlorophyll) and instead absorbs food through haustoria. They are rootlike structures that penetrate the tissue of a host plant and may kill it. The slender, string like stems of the dodder may be yellow, orange, pink, or brown in colour. It’s leaves are reduced to minute scales. The dodder’s flowers, in nodule like clusters, are made up of tiny yellow or white bell-like petals. fig-10: Haustoria in cuscuta The dodder’s seed germinates, forming an anchoring root, and then sends up a slender stem that grows in a spiral fashion until it reaches a host plant. It then twines around the stem of the host plant and forms haustoria, which penetrate through it. Water is drawn through the haustoria from the host plant’s xylem, and nutrients are drawn from its phloem. Meanwhile, the root rots away after stem contact has been made with a host plant. As the dodder grows, it sends out new haustoria and establishes itself very firmly on the host plant. After growing in a few spirals around one host shoot, the dodder finds its way to another, and it continues to twine and branch until it resembles a fine, densely tangled web of thin stems enveloping the host plant. Identify plants in your surroundings which are parasitic on other plants. Nutrition

in Human Beings Human digestive system is very complex in nature. Different parts are involved and perform different functions by using various digestive juices and enzymes. Let us observe the figure of digestive system and label the parts. The alimentary canal is basically a long tube extending from the mouth to the anus. We can see that this tube has different parts. Various regions are specialized to perform different functions. • What happens to the food once it enters our body? fig-11: Alimentary canal of man Free distribution by A.P. Government 13 salivary duct We eat various types of food which has to pass through the same digestive tract. It also has to be converted to substances small enough to be utilised by our body. This needs various processess that can be studied as follows. Passage of food through alimentary canal or gut salivary glands Food is cut and crushed by our teeth in the mouth and mixed with saliva to make it wet and slippery (also called as mastication). Saliva is secreted by three pairs of salivary glands. Two pairs are located at the side of the jaw and below the tongue. One pair is located in the palate. Saliva mainly contains an enzyme amylase (ptyalin) which helps in the breakdown of complex carbohydrates to simple ones. The tongue helps in mixing the food and pushing it into the next part. The lower jaw also helps in the whole process. epiglottis fig-12: Buccal cavity palate tongue We can find out the effect of salivary amylase on carbohydrates to observe what might be happening in our mouth. Activity-4 • Refer to activity - 7 action of saliva on wheat flour in the chapter Co ordination of life processes. ‘Thats the way with our body’. You can also perform the activity by using ‘Ganji’ (boiled rice water) The soft food mixed with saliva passes through oesophagus or food pipe by wave like movements called peristaltic movement to the stomach. At the stomach, food gets churned with gastric juice and HCl. Now the food is in semisolid condition. The digestion of food goes on as most proteins are broken down into smaller molecules with the help of enzyme pepsin acting on them. peristalitic wave esophagus stomach bolus fig-13: Peristaltic movement 14 X Class Food in the form of a soft slimy substance where some proteins and carbohydrates have already been broken down is called chy

me. Now the food material passes from the stomach to the small intestine. Here the ring like muscles called pyloric spincters relax to open the passage into the small intestine. The spincters are responsible for regulating the opening of the passage such that only small quantities of the food material may be passed into the small intestine at a time. Nutrition - Food supplying system The small intestine is the longest part of the alimentary canal. It is the site of further digestion of carbohydrates, proteins and fats. It receives the secretion of liver and pancreas for this purpose. These juices render the internal condition of the intestine gradually to a basic or alkaline one. Fats are digested by converting them into small globule like forms by the help of the bile juice secreted from liver. This process is called emulsification. Pancreatic juice secreted from pancreas contains enzymes like trypsin for carrying on the process of digestion of proteins and lipase for fats. Walls of the small intestine secrete intestinal juice which carry this process further that is small molecules of proteins are broken down to further smaller molecules. The same is the condition with fats. Carbohydrate digestion that started in the mouth and did not occur in the stomach, resumes now as the medium gradually changes to an alkaline one and the enzymes become active for carbohydrate breakdown. Activity-5 Studying the enzymes chart Let us study the chart showing different enzymes and digestive juices and their functions. Table-1: some enzymes and juices of the gut S.No. Enzyme/Substance Secreted by Secreted into Digestive juice Acts on Products 1 2 3 4 5 6 7 8 Ptyalin (salivaryamylase) Salivary glands Buccal cavity Saliva Carbohydrates Dextrins and maltose Pepsin Stomach Stomach Gastric juice Proteins Peptones Bile (No enzymes) Liver Duodenum Bile juice Fats Emulification breaking down of largef ats into small globules Amylase Pancreas Duodenum Pancreatic juice Carbhoydrates Maltose Pancreas Duodenum Pancreatic juice Proteins Peptones Pancreas Intestinal wall Duodenum Pancreatic juice Intestinal juice Fats Peptidases Small Intestine Small Intestine Intestinal juice Peptides Sucrose Small Intestine Small Intestine Intestinal juice Sucrose (Cane Sugar) Fatty acids and glycerol Amino acids Gluc

ose Trypsin Lipase • Name the enzymes which act on carbohydrates? Free distribution by A.P. Government 15 • Which juice contains no enzymes? • What are the enzymes that act on proteins? Transport of the products of digestion from the intestine into blood (through the wall of intestine) is called absorption. Internally, intestinal wall has a number of finger like projections called villi. The villi increase the surface area for absorption. Blood vessels and lymph vessels are present in the form of a network in the villi. Products of digestion are absorbed first into the villi and from here into the blood vessels and lymph vessels. Thus after maximum absorption of food in the small intestine the rest passes into the large intestine. Here most of the water present is taken up from this material. This material is then expelled through the anus which is the last part of the alimentary canal. This passage of undigested material from the body by the way of anus is called defecation. Food that passes out of the anus still contains considerable amount of proteins, fats and carbohydrates, roughages or fibres of either carbohydrates or proteins. We will learn some more points about the coordination about digestive system with other systems in the chapter coordination in life processess. Flow chart of human digestive system • What do you think is the process of digestion? • What are its major steps? Food Mouth Buccal cavity Pharynx Cardiac Stomach Pyloric Stomach Oesophagus Duodenum Small intestine Large intestine Anus Rectum Bile Pancreas Health aspects of the alimentary canal The human alimentary canal usually functions remarkably well considering how badly we treat it on occasions! Sometimes it rebels, and we either feel sick or have indigestion. 16 X Class Nutrition - Food supplying system Vomiting is the body’s method of ridding itself of unwanted or harmful substances from the stomach. The peristaltic movements of the stomach and oesophagus reverse their normal direction and the food is expelled. There are many causes of vomiting, but one of the most common is over eating, especially when the food contains a high proportion of fat. Vomiting also occurs when we eat something very indigestible or poisonous. When we have a greenish vomit usually called as ‘bilious’ or ‘liverish’, we get a bitter taste and it is often the result of having eaten ‘rich’ meals over several days. The liver is unable to cope with the

excessive fat and we get a feeling of nausea. Indigestion is a general term used when there is difficulty in digesting food. Healthy people can usually avoid problems related to digestion by: a) having simple, well balanced meals b) eating them in a leisurely manner c) thoroughly masticating the food d) avoiding taking violent exercise soon after eating food e) Drinking plenty of water and having regular bowel movements. A more serious form of indigestion is caused by stomach and duodenal ulcers. These conditions occur more often in people who may be described as hurried or worried. Thus, ulcers occur more often in busy people who get into the habit of hurrying over meals and rushing from one activity to another without sufficient rest. Those who are able to relax, who are not continually tensed up, and who live at a slower pace, seldom get ulcers. You studied about recent researches in the peptic ulcers caused by some bacteria in class IX. Proper functioning of all life processess require adequate amount of food in all living organisms. It is not just the intake of food but its assimilation and expulsion of wastes that play an important role. In take of fibre rich food avoids constipation. Diseases due to mal nutrition We know that food is the main source to maintain biological processes in a perfect manner. Our diet should be a balanced one which contains proper amount of carbohydrates, proteins, vitamins, mineral salts and fats. Two third of world population is affected by food related diseases. Some of them are suffering by consuming high calorific food. Most of them are facing various diseases due to lack of balanced diet. It is very important to discuss about food deficiency diseases. Free distribution by A.P. Government 17 Eating of food that does not have one or more than one nutrients in required amount is known as mal nutrition. Poor health, will full starvation, lack of awareness of nutritional habits, socio economic factors are all the reasons for mal nutrition in our country. Mal nutrition is of three types 1. Calory malnutrition, 2. Protein malnutrition, 3. Protein calory malnutrition. Let us observe harmfull effects of mal nutrition in children. fig-14: Kwashiorkor 1. Kwashiorkor disease: This is due to protein deficiency in diet. Body parts become swollen due to accumulation of water in the intercellular spaces. Very poor muscle development, swollen legs, fluffy face difficult to eat, diarrhoea, dry skin are the symptoms of this disease.

2. Marasmus: This is due to deficiency of both proteins and calories. Generally this disease occurs when there is an immidiate second pregnancy or repeated child births. Lean and week, swelling limbs, less devoloped muscles, dry skin, diarrhoea, etc., are the symptoms of this disease. 3. Obesity: This is due to over eating and excess of energy in take. It is a big health hazard. Obese children when grows, they will be target of many diseases like diabetes, cardio vascular, renal, gall bladder problems. Discuss about junk foods and other food habits which leads to obesity. fig-15: Marasmus Vitamin deficiency diseases Vitamins are organic substances. They are micro nutrients required in small quantities. Actually vitamins are not synthesised in the body, we do not generally suffer from vitamin deficiency. The source of vitamins to our body is through two ways. One is diet and other is bacteria present in the intestain that synthesises and supplies vitamins to the body. fig-16: Pellegra Vitamins are classified into two groups. One is Water soluble vitamins (Be-complex, vitamin C) and other is fat soluble vitamins (vitamin A, D, E and K). Let us study the following chart showing vitamins available sources and deficiency diseases. 18 X Class Nutrition - Food supplying system Vitamin Resources Deficiency diseases Symptoms Thiamine (B1) Cereals, oil seeds, vegetables, milk, meat, fish, eggs. Beri beri Riboflavin (B2) Milk, eggs, liver, kidney, green leafy vegetables. Glossitis Vomitings, fits, loss of appetite, difficulty in breathing, paralysis. Mouth cracks at corners, red and sore tongue, photophobia, scaly skin. Niacin (B3) Kidney, liver, meat, egg, fish, oil seeds. Pellagra Dermatitis, diarrhoea, loss of memory, scaly skin. Pyridoxine (B6) Cereals, oil seeds, vegetables, milk, meat, fish, eggs, liver. Anaemia Hyper irritability, nausea, vomiting, fits. Cyanocobalamine (B12) Synthesised by bacteria present in the intestine. Pernicious anaemia Lean and week, less appetite. Folic acid Liver, meat, eggs, milk, fruits, cereals, leafy vegetables. Anemia Diarrhoea, loss of leucocytes, intestinal mucus problems. Pantothenic acid

Sweet potatoes, ground nuts, vegetables, liver, kidney, egg. Burning feat Walking problems, sprain. Biotin Pulses, nuts, vegetables, liver, milk, kidney. Nerves disorders Fatigue, mental depression, muscle pains. Ascorbic acid (C) Green leafy vegetables, citrus fruits, sprouts. Scurvy Delay in healing of wounds, fractures of bones. Retinol (A) Leafy vegetables, carrot, tomoto, pumpkin, papaya, mango, meat, fish, egg, liver, milk, cod liver oil, shark liver oil. Eye, skin diseases Night blindness, xeropthalmia, cornea failure, scaly skin. Calciferol (D) Liver, egg, butter, cod liver oil, shark liver oil, (morning sun rays). Rickets Improper formation of bones, Knocknees, swollen wrists, delayed dentition, week bones. Tocoferol (E) Fruits, vegetables, sprouts, meat, egg, sunflower oil. Fertility disorders Sterility in males, abortions in females. Phylloquinone (K) Green leafy vegatables, milk. Blood clotting Delay in blood clotting, over bleeding. Free distribution by A.P. Government 19 Key words Glucose, starch, cellulose, chloroplast, grana, stroma, light reaction, dark reaction, heterotrophic nutrition, parasitic nutrition, haustoria, Alimentary canal, salivary glands, peristaltic movement, amylase, ptyalin, pepsin, chyme, sphincter, digestion, pancreas, enzymes, villi, bile juice, lipase, fat, liver, emulsification. What we have learnt • Autotrophic nutrition involves the intake of simple inorganic materials like some minerals, water from the soil. Some gases from the air. By using an external energy source like the Sun to synthesis complex high energy organic material. • • Photosynthesis is the process by which living plant cells containing chlorophyll, produce food substances [glucose & starch] from Carbon dioxide and water by using light energy. Plants release oxygen as a waste product during photosynthesis. Photosynthesis process can be represented as 6CO2 + 12H2O light Chlorophyll C6H12O6+6H2O+6O2 • The materials required for photosynthesis are light: Carbon dioxide,

Water, photosynthetic pigment chlorophyll. • Chloroplast are the sites of photosynthesis. Light reaction takes place in the grana region and light independent reaction takes place in the storma region. • The end products of photosynthesis are Glucose water and Oxygen. • During photosynthesis the important events which occurs in the chloroplast are a) Conversion of light energy into chemical energy b) Splitting of water molecule c) Reduction of carbon dioxide to carbohydrates • Heterotrophic Nutrition involves the intake of complex material prepared by other organisms. • The form of nutrition differs depending on the type and availability of food material as well as how it is obtained by the organism. • In single celled organisms the food may be taken in by the entire surface but as the complexity of the organism increases different parts becomes specialized to perform different functions. • The large complex food molecules such as carbohydrates, proteins, lipids, etc., are broken down in to simple molecules before they are absorbed and utilized by the animals. This process of breaking down of complex molecules into simple molecule is called digestion. • In human beings the food eaten is broken down in various steps with the help of enzymes secreted by digestive glands which are associated with the alimentary canal and the digested food is absorbed in small intestine to be sent to all cells in the body. 20 X Class Nutrition - Food supplying system • The digestive system includes the alimentary tract and several associated organs. The functions of system are as follows : a) Ingestion: b) Digestion: c) Absorption: d) Defecation: Taking of food into the body Breaking up of complex food substances into the simple substances by specific enzymes. So that they can be used by the body. The passage of digested food through the walls of alimentary tract (particulars in small intestine ) into circulatory system. The passage of undigested material from the body by the way of anus. Improve your learning 1. Write differences between (AS1) a) autotrophic nutrition - heterotrophic nutrition c) Light reaction - dark reaction b) Ingestion - digestion d) Chlorophyll - chloroplast 2. Give reasons (AS1) a) Why photosynthesis is considered as the basic energy source for most of living world? b) Why is it better to call the dark phase of photosynthesis as a light independent phase? c) Why is it necessary to destrach a plant before performing any experiment on photosynthesis

? d) Why is it not possible to demonstrate respiration in green plant kept in sunlight? 3. Give examples (AS1) a) Digestive enzymes c) Vitamins b) Organisms having heterotrophic nutrition d) Food deficiency diseases 4. Where do plants get each of the raw materials required for photosynthesis?(AS1) 5. Explain the necessary conditions for autotrophic nutrition and what are its by products?(AS1) 6. With the help of chemical equation explain the process of photosynthesis in detail? (AS1) 7. Name the three end products of photosynthesis? (AS1) 8. What is the connecting substance between light reaction and dark reaction? (AS1) 9. Most leaves have the upper surface more green and shiny than the lower ones why? (AS1) 10. Explain the structure of chloroplast with a neatly labeled sketch. (AS1) 11. What is the role of acid in stomach? (AS1) 12. What is the function of digestive enzyme? (AS1) 13. How is the small intestine designed to absorb digested food, explain. (AS1) 14. How do fats digested in our bodies? Where does this process takes place? (AS1) 15. What is the role of saliva in the digestion of food? (AS1) 16. What will happen to protein digestion as the medium of intestine is gradually rendered alkaline? (AS1) 17. What is the role of roughages in the alimentary track? (AS1) 18. What is malutrition explain some nutrition deficiency diseases. (AS1) 19. How do nongreen plants such as fungi and bacteria obtain their nourishment? (AS2) 20. If we keep on increasing CO2 concentration in air what will be the rate of photosynthesis?(AS2) Free distribution by A.P. Government 21 21. What happens to plant if the rate of respiration becomes more than the rate of photosynthesis?(AS2) 22. Why do you think that carbohydrates are not digested in the stomach?(AS2) 23. What process you follow in your laboratory to study presence of starch in leaves?(AS3) 24. How would you demonstrate that green plant release oxygen when exposed to light?(AS3) 25. Visit a doctor and find out keeping in view of digestion. Prepare a chart and display in your classroom. (AS4) i) Under what condition

ll from leaves b) Remove starch from leaves c) Ensure that no photosynthesis occurred d) Ensure that leaves are free from the starch 10. The digestive juice without enzyme is a) Bile b) Gastric juice c) Pancrtatic juice d) saliva 11. In single celled animals the food is taken a) By the entire body surface b) Mouth c) Teeth d) Vacuoles 12. Which part of the plant takes in carbondioxide from the air for photosynthesis a) Root hair b) Stomata c) Leaf veins d) Sepals ( ( ( Free distribution by A.P. Government ) ) ) ) 23 Chapter 2 Respiration - The energy releasing system Using food to carry out life processes is key to life for all living beings in both multicellular or unicellular. In the chapter, on nutrition we have discussed how the body draws out nutrients from the food taken in. The food provides energy for all bodily activities only after break down through the process known as respiration. Thus, respiration leads to final utilization of food. When oxygen is plentiful respiration normally takes over. Cells of the living body use food constantly to help our body to function properly. They require the presence of gas, food material and some chemicals. The term ‘respiration’ derived from Latin word ‘respire’ meaning ‘to breathe’, refers to the whole chain of processes from the inhalation of air to the use of oxygen in the cells. To begin with, we shall study the relation of gases and the process of respiration. Discovery of gases and respiration The term respiration came into use, a century after the word breathing was used, way back in the 14th century. It was used much before people knew that air is a mixture of gases. They hardly knew anything about all the life processes that took place internally in a living body. Respiration which was used as a medical term, usually referred to as a process involving passage of air and production of body heat. It was not until 18th century when Lavoisier and Priestley did a comprehensive work on properties of gases, their exchange and respiration that we came to know something about how the process of gaseous exchange goes on, in our body. You have already studied about Respiration - The energy releasing system fig-1: Lavoisier 24 X Class some of Priestley’s experiments in earlier classes (You have an account of it in the chapter on nutrition as

well). Recall the concepts and answer the following. • Can it be said that Priestley’s experiment helped us to find out more about composition of air? How? Lavoisier also carried out several experiments to understand the property of gases. In his early experiments, it is clear that Lavoisier thought that the gas liberated on heating powdered charcoal in a belljar kept over water in a trough was like fixed air. In those days carbon dioxide was known as fixed air. The next series of experiments dealt with the combustion of phosphorus in a belljar. From these studies Lavoisier showed that whatever in the atmospheric air which combined with the phosphorus, was not water vapor. His final words are that the substance which combines with the phosphorus is “either air itself, or another elastic fluid present, in a certain proportion, in the air which we breathe”. This was the respirable air, a component of air that also helped in burning. • What was produced by combustion according to Lavoisier? • What did Lavoisier find out about air from his experiments? • What conclusion can be drawn from Lavoisier’s experiments? Lavoisier noted that there was a profound difference between the air in which combustion of a metal had been carried out and the one which had served for respiration. The air that we breathe out precipitated lime water while that after heating metal did not. From this he deduced that there were two processes involved in respiration, and that of these he probably knew only one. Therefore, he carried out another experiment by which he showed that about one sixth of the volume of ‘vitiated air’(a term used then to show air from which the component needed for burning had been removed) consists of chalky acid gas (fixed air). Therefore, to recreate common air from vitiated air, it was not enough merely to add the appropriate amount of air needed for burning or respirable air; the existing chalky acid gas must also be removed. He drew immediately the logical conclusion regarding the process of respiration. Either eminently respirable air is changed in the lungs to chalky acid air; or an exchange takes place, the eminently respirable air being absorbed, and an almost equal volume of chalky acid air being given up to the air from the lungs. He had to admit that there were strong grounds for believing that eminently respirable air did combine with the blood to produce the red colour. fig-2: Priestley Free distribution by

A.P. Government 25 Lavoisier’s findings lead way to several other researchers. • Which gas do you think is Lavoisier talking about when he says chalky acid gas? • Which gas according to him is respirable air? • What steps in the process of respiration does Lavoisier mention as an inference of his experiments? A few lines from a textbook of Human Physiology, written by a renowned chemist, John Daper around mid-19th century goes like this.. ‘‘The chief materials which a living being receives are matter that can be burnt, water and oxygen gas; and out of the action of these upon one another, all the physical phenomena of its life arise. What the body expels out is water, oxide of carbon, phosphorous, sulphur and others.’’ Thus, we can see that the role of major compounds and elements in the process of respiration was known by mid19thcentury. The events involved were not very clearly understood, but, people believed that there was some relationship of the heat produced in the body and the process of respiration. • It is a common observation that our breath is warmer than the air around us; does respiration have anything to do with this? Let us study the events involved in respiration in human beings to figure it out. Events / Steps in Respiration There are no strict demarcations of events involved in the process of respiration. It is a very complex process of several biochemical and physical processes. But for a general understanding on what goes on, we shall study under the following heads. Breathing Gaseous exchange at lungs level Gas transport by blood Gaseous exchange at tissue level Air movement into and out of lungs Exchange of gases between alveoli and blood Transport of oxygen from blood capillaries of alveoli to body cells and return of carbon dioxide Exchanging of oxygen from blood into the cells and carbon dioxide from cells into the blood Cellular Respiration Using oxygen in cell processes to produce carbon dioxide and water, releasing energy to be used for life processes 26 X Class Respiration - The energy releasing system Breathing In the previous classes we did experiments to find out what was there in the air we breathe out. We had seen that in a set up with lime water, it turned milky white fast as we breathe out into it as compared to a similar set up in which normal air was passed with the help of a syringe or pichkari in lime water. (Exper

imental set up to test the presence of Carbon dioxide in exhaled air). Arrange apparatus as shown in figure and try to do the experiment once again to find out what happens. lime water water • What does this experiment indicate? • Which gas turns lime water milky? • Which gas do you think might be present in greater quantities in fig-3: Respiratory gases the air we breathe out as compared to air around us? • We are also aware of the fact that water vapor deposits on a mirror if we breathe out on it. • Where does this water vapor come from in exhaled air? We shall have to study the pathway of air in our body through our respiratory system and the mechanism of breathing in respiration to find out how the exhaled air comes out (Fig showing the respiratory system/ pathway). By “respiratory system” we usually mean the passages that transport air to the lungs and to the microscopic air sacs in them, called alveoli (where gases are exchanged between them and blood vessels) and vice versa. Pathway of air Let us observe the pathway of air from nostril to alveolus. nasal cavity nostril epiglottis pharynx larynx trachea bronchi bronchioles lung capillaries in which O2 CO2 exchanges occur and alveoli fig-4: Respiratory system of man Free distribution by A.P. Government 27 Nostrils: Air usually enters the body through the nostrils Pharynx: Nasal cavity: Air is filtered. The moist surface of the lining of the nasal cavity, and the hairs growing from its sides, remove some of the tiny particles of dirt in the air. In addition, as the inhaled air passes through the nasal cavity, its temperature is brought close to that of the body, and it takes up water vapour so that it becomes more moist than before. Warming and moistening goes on in this common passage of digestive and respiratory system. Epiglottis, a flap like muscular valve controls movement of food and air towards their respective passages. This stiff box contains our vocal cords. When air passes out of the lungs and over the vocal cords, it causes them to vibrate. This produces sounds on the basis of our speech, song etc. Wind pipe channeling air to lungs. Touch your neck to feel the tube like structure. At its lower end the trachea or the wind pipe divides into two bronchi-one leading to each lung.

Bronchioles: Each bronchi is further divided into smaller and smaller Bronchus: Trachea: Larynx: Alveolus: Blood: branches called bronchioles. These finally terminate in clusters of air sacs called alveoli in the lungs which are very small and numerous. Gaseous exchange takes place here as blood capillaries take up oxygen and expel carbon dioxide. Carries oxygen, collects CO2 to each and every cell of the body. The whole passage from nostrils to alveolus is moist and warm. Do you know? The interior of lung is divided into millions of small chambers, thus tremendously increasing the moist surface available for transfer of gases between air and blood. The linings of the lungs are much folded and so their total surface is enormous. If all alveoli of our lungs are spread out they will cover an area of nearly 160 m2. 28 X Class Respiration - The energy releasing system Epiglottis diverts air to lungs Epiglottis diverts food mass away from opening of larynx Think and discuss • What will happen if the respiratory tract is not moist? • Are both lungs similar in size? • Why alveolus are so small and uncountable in number? Epiglottis and passage of air From the nasal cavity, the air goes into the pharynx. There is a tricky problem here. From the pharynx there are two passages, beginning with nearly same opening and ending into separate ones, one to the lungs and one to the stomach. It is important that air goes into one and food into the other. It is also important that food does not enter the tube through which air goes into the lungs. The traffic is kept properly channeled by a flap like valve, the epiglottis that protects the tube to the lungs, arresting entry of food. Observe the following figures and discuss in your class how epiglottis works while breathing or swallowing fig-5(a): Breathing fig-5(b): Swallowing This valve is partly closed when we swallow food; it deflects food down to the stomach and keeps it out of the trachea or wind pipe which is the route to the lungs. The epiglottis opens more widely when we take a breath, and air enters the lungs. Nervous regulation is important in guiding the function of epiglottis and passage of food and air. Let us try to do an activity to feel what

happens when we swallow food. • Why we are advised not to talk while eating food? Activity-1 Keep your palm around an inch away from your nose, feel you are breathing out, do not remove it until you have finished the activity. Breathe steadily for 1-2 minutes. Now take a piece of any fruit, chew and before swallowing it keep the fingers of the other palm on your neck, now swallow it. • What did you notice? What happens to your breath as you try to swallow? Free distribution by A.P. Government 29 rib bones chest wall muscles lung diaphragm • What is helping you to swallow without deflecting it to the wind pipe? Mechanism of respiration in human beings We know that breathing is the process of inhaling and exhaling. The organs involved are mainly the lungs. You can’t see your lungs, but it’s easy to feel them in action. Put your hands on your chest and breathe in very deeply. You will feel your chest getting slightly bigger. Now breathe out the air, and feel your chest return to its regular size. You’ve just felt the power of your lungs! The lungs themselves can neither draw in air nor push it out. Instead, the chest wall muscles and another flexible flattened muscle called diaphragm helps the lungs in moving air into and out of them. See how the diaphragm works in the figure. • What is the role of diaphragm and ribs in respiration? Are both fig-6: Movement of diaphragm active in man and woman? The chest wall is made up of ribs, muscles, and the skin. The ribs are attached at an angle to the spine (if you run your finger along one of your ribs, you will notice that it extends downward from the spine). When we inhale, the chest wall moves up and expands. This causes an increase in the volume of the chest cavity. The diaphragm may be imagined as the ‘floor’ if you think of the chest cavity as a “room.” When the diaphragm is relaxed when we breath out, it is in the shape of a dome with the convex side of the dome extending into the chest cavity. When the diaphragm contracts during inhalation it flattens out a bit or the dome moves downward. As a result, the volume of the chest cavity is increased. When the diaphragm flattens and the volume of the

chest cavity is increased, its internal pressure decreases and the air from the outside rushes into the lungs. This is inspiration (inhalation). Then the reverse occurs. The chest wall is lowered and moves inward, and the diaphragm relaxes and assumes its dome shape. These changes increase the pressure on the lungs; their elastic tissue contracts and squeezes the air out through the nose to the external atmosphere. This is expiration (exhalation). Respiration - The energy releasing system fig-7: Movement of rib cage during inhalation, exhalation 30 X Class Do you know? Our lungs are spongy in nature. They are not of the same size. The lung towards left is slightly smaller making space for your heart! Lungs are protected by two membranes called pleura. A fluid filled between these membranes protects the lungs from injury and also aid in the expansion of the spongy and elastic lung muscle, as they slide one over the other. You must have noticed that your own breathing is slow and shallow when you are at rest. It is deeper and faster when you exercise hard. Indeed, patterns of breathing show a great range, for they are coordinated with moment-by-moment needs of the body for supply of oxygen and removal of carbon dioxide. What other situations affect your breathing? It has been found that all movements of breathing stop at once when the nerves leading from the brain to the respiratory muscles are cut. • What can be concluded from this? • What happens during the process of breathing? • Which gas needs to be removed from our body during exhalation? Where does the extra amount of gas come from? • What is the composition of inhaled air? • When exhaled air is compared with inhaled air, is there any differ- ence in composition? Gaseous Exchange (alveoli to capillaries) Gaseous exchange takes place within the lungs by diffusion from the alveoli to blood capillaries and vice versa. The carbon dioxide in the blood is exchanged for oxygen in the alveoli. These tiny air sacs in the lungs are numerous and only one cell thick. They are surrounded by capillaries that are also only one cell thick. Blood, dark red in colour flows from the heart through these capillaries and collects oxygen from the alveoli. At the same time, carbon dioxide passes out of the capillaries and into the alveoli. When we breathe out, we get rid of this carbon dioxide. The bright

red, oxygenrich blood is returned to the heart and pumped out to all parts of the body. carbon dioxide oxygen fig-8: Diffussion path way for gaseous exchange between lung and blood capillaries Free distribution by A.P. Government 31 branchiole alveolus blood cells capillary network As a result of gaseous exchange, the composition of inhaled and exhaled air is different. See the table given below. Approximate values are given in the table • Why does the amount of Oxygen vary between exhaled and inhaled air? Gas Oxygen Carbon dioxide Nitrogen % in inhaled air % in exhaled air 21 0.04 79 16 4 79 • What has raised the percentage of carbon dioxide in exhaled air? Do you know? The total lung capacity of human being is nearly 5800ml. Normally at rest who inhale or exhale approximately 500ml of air. 120ml of air remains in lungs after complete exhalation. Recall the activity of lung capacity performed by you in class VII in the chapter ‘Respiration in Organisms’. Transportation of gases We know that air is a mixture of gases, that fills the lungs and the alveoli when that enters our body. The relative amount of different gases in air and their combining capacity with haemoglobin and other substances in blood determine their transport via blood in the body. When oxygen present in the air is within normal limits (around 21%) then almost all of it is carried in the blood by binding to haemoglobin, a protein (quite like chlorophyll, the only major difference being it has iron in place of magnesium as in chlorophyll) present in the red blood cells. As oxygen is deffused in the blood, it rapidly combines with the haemoglobin to form oxyhaemoglobin. Not only haemoglobin can combine with oxygen, but the reverse can also happen to yield a molecule of haemoglobin and oxygen. Carbon dioxide is usually transported as bicarbonate, while some amount of it combines with haemoglobin and rest is dissolved in blood plasma. Study the following equation for better understanding. HbO2 Hb + O2 32 X Class Respiration - The energy releasing system HbO2 Hb + O2 Do you know? If haemoglobin is exposed to air at sea level, nearly every molecule combines with oxygen to form oxyhaemoglobin. At a height of 13 km (about 8 miles) above sea level,

the concentration of oxygen is much lower about one fifth at sea level. Under these conditions only about half as increase the pressure on he air out through the nose h of the trachea. the hairs growing from its fig-9: Mountaneer many molecules of oxygen combine with haemoglobin to form oxyhaemoglobin. This is important, because blood cannot carry enough oxygen to the tissues if haemoglobin is combined with few oxygen molecules. In fact, human life is impossible at such an altitude without a supplementary supply of oxygen. Provision for such a supply is built into modern aircraft, which have pressurized cabins that maintain an enriched air supply. When we go deep into the sea we will face another type of problems. Gaseous exchange (capillaries to cells and back) In the capillaries over the tissues, haemoglobin meets a very different environment. The tissue cells are continually using oxygen, hence, the concentration of oxygen is quite low in them. It might be only one third of that in the lungs. As the concentration of oxygen is so low, oxyhaemoglobin releases the oxygen molecule that enters the cells. In the reactions that occur within cells in our bodies, carbon dioxide and water are produced and energy is released to be used up for different purposes. Cellular respiration The term cellular respiration refers to the pathway by which cells release energy from the chemical bonds of food molecules that enter them. It provides that energy for the essential processes of life. So living cells must carry out cellular respiration. It can be in the presence of oxygen that is ‘aerobic respiration’ or in its absence that is ‘anaerobic respiration (fermentation)’. Cellular respiration in prokaryotic cells like that of bacteria occurs within the cytoplasm. In eukaryotic cells cytoplasm and mitochondria are the sites of the reactions. The produced energy is stored in mitochondria in the form of ATP. That is why mitochondria are called “power houses of cell”. The exact chemical details of the breakdown of sugar or other foods within a living cell does not take place as a single reaction, but occurs in a series of small steps. How does this affect the energy release? As the change in the chemical nature of the molecule from one stage to the next is slight, in any step small amount of energy is released. The complete breakdown of a sugar molecule with the release of all its available energy Free distribution by A.P

. Government 33 outer membrane inner membrane criste matrix fig-10: Mitochondria involves a series of different chemical reactions. From the breakdown of glucose the energy is released and stored up in a special compound, known as ATP (adenosine triphosphate). It is a small parcel of chemical energy. The energy currency of these cells is ATP an energy rich compound that is capable of supplying energy wherever needed within the cell. Each ATP molecule gives 7200 calories of energy. This energy is stored in the form of phosphate bonds. If the bond is broken the stored energy is released. • Do cells of alveoli or lungs also require oxygen to carry out cellu- lar respiration? Why/Why not? In short, at cellular level we could have the following pathways starting with glucose (It is one example, remember that there are other components of food as well). Absence or low amount of oxygen (anaerobic respiraton and fermentation) Lactic acid + Energy Ex: Bacteria Ethanol + CO2+ Energy Ex: Yeast Presence of Oxygen (aerobic respiration) CO2 + H2O + Energy Ex: Plants and animals Glucose Pyruvate (3 carbon compound) + Energy Do you know? Glucose is the most commonly used sugar for deriving energy in plants, animals and in microorganisms. In all these organisms the glucose is oxidized in two stages. In the first stage it is converted into two molecules of pyruvic acid. In the second stage if oxygen is available pyruvic acid is oxidized to CO2 and water, large amount of energy is released. If oxygen is inadequate or not utilised pyruvic acid is converted into either ethanol or lactic acid and very little amount of energy (nearly one tenth of that is produced with adequate amount of oxygen) is released. Can energy be released without oxygen? • After undergoing strenous exercise we feel pain in muscles, does adequate oxygen reach the muscles? • What is being formed in the muscles? 34 X Class Respiration - The energy releasing system When you sprint a hundred yards, you do a considerable amount of muscular work. But you do not start a race by standing on the track and panting for a few minutes to stoke up with oxygen first. In fact you can run the race with very little extra breathing. The fastest sprinters do not breathe at all when running a hundred yards. After you have reached the destiny, however, you feel very different. Depending on

your state of training, and on how hard you ran, you will pant for some minutes after the race, until your breathing gradually returns to normal. fig-11: Athlete (Strenous excercise) These facts could be linked up with what we have learned so far about ATP. It might be that the race was run on the energy produced when the ATP already present in your muscles was being converted to ADP. Unfortunately this pleasantly simple idea is inadequate, because we only carry sufficient ATP in a muscle to last for about half a second when doing vigorous exercise. There must be some other explanation for the way in which we can produce energy first and then use up oxygen later. One approach in the study of this problem was to analyze the blood of a person during and after exercise. For obvious reasons the athlete taking part in the experiment had to stay still where the apparatus was. He pedaled a stationary bicycle, or ran on a tread mill (belt moving as fast backwards as the athlete moved forwards). Some results are shown in the graph. Vigorous exercise lasted for nine minutes (shown by the bar at the base of the diagram) and regular blood samples were taken and analyzed. One particular compound in the blood, lactic acid, was found to vary greatly in its concentration as you can see from the graph. Observe the graph of lactic acid accumulation in the muscles of an athelete and answer the following questions. (Graph showing varying amount of lactic acid in the muscles) x - axis = Time in minutes y - axis = Concentration of lactic acid in blood mg/cm3 Graph showing effects of vigorous excercise on the concentration of lactic acid in blood. Free distribution by A.P. Government 35 a. What was the concentration of lactic acid in the blood to start with? b. What was the greatest concentration reached during the experiment? If the trend between points C and D were to continue at the same rate, c. how long might it take for the original lactic acid level to be reached again? (Hint: extend the line CD until it reaches the starting value.) d. What does high level of lactic acid indicate about the condition of respiration? Accumulation of lactic acid results in muscular pain. If we take walk, brisk walk, slow jogging, running for same distance we feel that there an increase in pain levels this is because of lactic acid accumulation. It seems as if the lactic acid was being produced rapidly by the active

muscles, and then only gradually removed from the blood after exercise. What is surprising is that the athlete needs a great length of time to recover. The simplest explanation we can produce at-this stage is that the sugar in the working muscles was being changed to lactic acid. The energy stored in lactic acid molecules is less than that in sugar molecules, and if the acid comes from the sugar then the energy released could be used to rebuild ATP from ADP and phosphate. During a 100 m race a well-trained athlete can hold his breath all the time it is not until afterwards that he pants. In this case, the muscles are using the energy released during the anaerobic breakdown of glucose. It is not until afterwards that the athlete obtains the oxygen needed in order to remove the lactic acid. Therefore, when we under-take strenuous exercise we build up what is called an oxygen debt which has to be repaid later. In a longer race athletes have to breathe all the time, so some lactic acid is removed while they are running, and they can go on for longer before becoming exhausted. The presence of lactic acid in the blood is the main cause of muscle fatigue, but if the body is rested for long enough the tiredness goes. Anaerobic respiration We have found that living things produce carbon dioxide and give out energy. If these processes are caused by an oxidation process, what happens if the oxygen supply is cut off? If human muscles can go on releasing energy when they are short of oxygen, what can cells of other living organisms do? Let us find out by doing some experiments. 36 X Class Respiration - The energy releasing system Lab Activity Some experiments with yeast To test this idea we can see whether it is possible to detect any rise in temperature and the production of carbon dioxide, when living organisms are kept away from a supply of oxygen. thermometer liquid paraffin Yeast grows rapidly if it is supplied with glucose in solution. Indeed, wild yeasts are normally found growing on the skins of fruits like grapes and apples, from which they derive their food supplies. Our immediate problem is to remove the oxygen from the glucose solution and yeast. 1. You can remove dissolved oxygen from glucose solution by heating it for a minute, and then cooling it without shaking. Now put in some yeast; the supply of oxygen from the air can be cut off by pouring one centimetre layer of liquid paraffin on to the mixture. If you wish to check that the oxygen has been removed

Arrange apparatus as shown in the figure and heat it over a flame. Does it melt? What happen if you heat for somemore time? glucose test tube heat delivery tube lime water fig-13: CO2 - a by product of energy release When glucose burns, carbon dioxide and water are produced and energy is released as heat. We know that combustion of glucose gives us carbon dioxide, water and energy while from the respiratory equation we get the same products. But essentially the processes must differ due to following reasons. 1. Glucose must be burnt at high temperature in the laboratory to liberate energy, if it happened in our cells,all cells would be burnt. 2. Once glucose starts burning we can’t stop the process easily, but living cells are able to exercise control over the sort of burning of glucose in the presence of oxygen. 38 X Class Respiration - The energy releasing system 3. Water normally stops combustion from taking place while cells con- tain a lot of water and respiration still goes on. What can you conclude from this? Heat production by living organisms Heat production was a feature of burning glucose or sugar as you observed earlier. Living animals and plants usually produce energy in the form of heat. We feel warm when we wear sweater in winter season. We know that sweater prevents loss of heat energy produced by the body. Does this suggest any way in which our bodies lose heat to the surroundings? • What are the other ways in which our body loses heat? Heat is constantly lost from the body surface thus it must be continuously generated within our bodies to replace what has been lost to keep the body temperature constant. • Is the rate of heat production always the same? In the course of vigorous activity, a greater amount of heat is generated. We know that we feel hot after some form of strenuous exercise such as running. During celular respiration energy is released. Some part of energy is stored in the form of ATP. Some part of energy is utilised in our day to day life activities. And the excess amount of energy is released in the form of heat. But in case of vigorous activity like running we need more amount of energy. For this the rate of respiration is increased. So heat is also released in excess quantity. That’s why we feel warm. If the oxygen is not sufficient during vigorous excersise muscles start anerobic respiration. Hence, lactic acid is formed. We know that accumulation of lactic acid causes pain in muscle. We reach normal position

after some rest. Deep breath helps us to restore energy in our body. Refer in annexure about Yoga Asanas. Evolution in gases exchanging system Exchange of gases is a common life process in all living organisms, but it is not same in all. Single celled organisms Amoeba or multicellular organisms like Hydra and Planarians obtain oxygen and expel carbon dioxide directly from the body by the process of diffusion. In other multicellular animals special organs are evolved. Animals either terrestrial or aquatic adopted to different types of respiration and possess different types of respiratory organs mostly depending on the habitat in which they live. Body size, availability of water and the type of their circulatory system Free distribution by A.P. Government 39 are some of the reasons for the animals to develop different types of respiratory organs. We will see tracheal respiratory system in insects like cockroach, grashopper etc. Tracheal respiratory system consists of series of tubes called trachea. This is divided into fine branches called tracheoles which carry air directly to the cells in the tissues. Some aquatic animals like fishes have developed special organs for respiration which are known as gills or branchiae. Blood supplied to gills through capillaries which have thin walls which gases are exchanged. This is called branchial respiration. Fish keeps its mouth open and lowers the floor of the oral cavity. As a result water from outside will be drawn into the oral cavity. Now the mouth is closed and the floor of the oral cavity is raised. Water is pushed into the pharynx and is forced to gill pouches through internal branchial apertures. Gill lamellae are bathed with water and gas exchange takes place. Respiration through skin is called cutaneous respiration. Frog an amphibian can respire through cutaneous and pulmonary respiration processes. Terrestrial animals like reptiles, birds and mammals, respire through lungs. Ask your teacher how crocodiles and dolphins respire? Respiration in Plants water film air spaces stomata fig-14: Leaf as a respiratory organ fig-15: Lenticells on stem You already know about stomata in leaf where gaseous exchange takes place in plants. There are other areas on the plant body as well through which gaseous exchange take place like surface of roots, lenticels on stem etc. (Fig showing stomata and lenticels). Some plants have specialized structures like breathing roots of mangrove plants as well as the tissue

in orchids that produces oxygen is also required by plants to produce energy and carbon dioxide is released. But CO2 is required elsewhrere in the plants try to identify them. Conduction within the plant The stomatal opeinings lead to a series of spaces between the cells inside the plant. Which form a continuous network all over the plant. The spaces are very large in the leaves, much smaller in other parts of the plant. The air spaces are lined with water where the oxygen is dissolved in this and passes 40 X Class Respiration - The energy releasing system through the porous cell walls into the cytoplasm. Here the sugar is broken down into carbon dioxide and water with the liberation of the energy. The carbon dioxide passes out into the air spaces by a similar method. The whole system works by diffusion; as the oxygen is used up by the cells a gradient develops between the cells and the air in the spaces. Similarly between the air in the spaces and the air outside the stomata and lenticels, so oxygen passes in. In the same way, as more carbon dioxide is released by the cells a gradient occurs in the reverse direction and it passes out to the environment. Aeration of roots Most plants can aerate their roots by taking in the oxygen through the lenticels or through the surface of their root hairs (as their walls are very thin). They obtain oxygen from the air spaces existing between the soil particles. But, plants which have their roots in very wet places, such as ponds or marshes, are unable to obtain oxygen. They are adapted to these water-logged conditions by having much larger air spaces which connect the stems with the roots, making diffusion from the upper parts much more efficient. fig-16: Aerial roots The most usual adaptation is to have a hollow stem. Next time when you are by a pond or marsh cut the stems of some of the plants which are growing there and see how many are hollow compared with a similar number of species of plants growing in normal soil. The problem of air transport is more difficult for trees and not many survive with their roots permanently in water. An exception is the mangrove tree of the tropics which forms aerial roots above the soil surface and takes in oxygen through these roots. To know more about respiration in plants we should perform the following activities. Activity-3 Take a handful of moong or bajra seeds. Soak the seeds in water a day before to perform your experiment. Keep these soaked

seeds in a cloth pouch and tie with a string tightly. Keep the cloth pouch in a corner of your class room. Next day collect the sprouts/ germinated seeds from the pouch, keep it in a glass bottle/plastic bottle(around 200 ml capacity). Take a small injection bottle, fill three fourth of the bottle sprouted seeds beaker with lime water fig-17: Evolved CO2 in respiration Free distribution by A.P. Government 41 with lime water. Tie a thread to the mouth of the small bottle; insert it in the bottle carefully and let it hang by the thread. Close the plastic bottle tightly. Make a similar set with unsprouted seeds. Keep this set undisturbed for one or two days. During this time observe the color of lime water in both the sets. In which set does the color change faster? Why? Activity-4 thermometer flask germinating seeds fig-18: Heat evolved during respiration Take sprouts which were prepared for above activity in a thermos flask. Remove the lid and prepare a cork (with thermocol, or rubber or any other material) through which you can bore a hole to insert a thermometer. Take care that the bulb of the thermometer should dip in the sprouts. Close the flask with this tight fitting cork. Record the temperature every two hours. You are advised to do this for at least 24 hours. • Make a graph by using your observations. Is there any increase in temperature? • • Does the temperature increase steadily or does it abruptly increase at a time of the day? • Where does the heat come from? Photosynthesis versus Respiration Plants carry out photosynthesis, which means that they produce their own food from atmospheric CO2 using light energy from the sun. This process is a complex series of steps involving the conversion of light energy into chemical energy, which is then used to synthesize sugars from carbon dioxide. This is a process of synthesis or an anabolic process which occurs in the chloroplasts. The equation below summarizes the photosynthetic process CO2+ H2O Light energy Chlorophyll (CH2O) n+ O2 Sugar Once produced, the sugars can then be used for the process of respiration to provide energy to run all life processes. Respiration as we know is not just the exchange of gasses. It is the process of breakdown of complex food molecules or a catabolic process to produce chemical or potential energy. This can be summarized by the equation (CH

2O)n+ O2 CO2+ H2O + Energy 42 X Class Respiration - The energy releasing system Photosynthesis and respiration appear to be opposing reactions, but both have very different biochemical pathways and are essential for a plant’s metabolism. Photosynthesis takes place in the chloroplast to produce sugars, starch and other carbohydrates for the plant’s metabolic needs. Cellular respiration occurs in mitochondria where these carbohydrates are “burned” to produce chemical energy to function at the cellular level. During day time, the rate of photosynthesis is usually higher than that of respiration while at night it is just reverse in most plants. Temperature, humidity, light intensity etc. seem to affect the ratio of photosynthesis and respiration in plants. Key words Aerobic respiration, Anaerobic respiration, Alveoli, Trachea, Bronchi, Bronchioles, Epiglottis, Pyruvate, Anabolic, Catabolic. What we have learnt • By “respiratory system” we usually mean the passages that transport air to the lungs and to the microscopic air sacs in them, called alveoli (where gases are exchanged) and vice versa. • The term ‘respiration’ refers to the whole chain of processes from the inhalation of air to the use of oxygen in the cells. • Lavoisier found that the air that we breathe out precipitated lime water while that after heating metal did not. He also found that something even beyond lungs occurred to produce carbon dioxide (he knew it as fixed air) and body heat. • Air passes from nostrils to nasal cavity to pharynx, larynx, trachea, and bronchi, bronchioles to alveoli and blood and back through the same route. • Gas exchange in the lungs takes place in the tiny air sacs called alveoli in the lungs. The lungs have millions of alveoli and each lies in contact with capillaries. Oxygen and carbon dioxide diffuse readily across a combination of the alveolar wall, the capillary wall and a thin layer that lies between them. • Diaphragm is a muscular tissue present at the floor of the chest cavity. • During inspiration (inhalation) the volume of the chest cavity is increased as the diaphragm contracts and dome flattens out, its internal pressure decreases and the air from the outside rushes into the lungs. Free distribution by

A.P. Government 43 sides, remove some of the tiny particles of dirt in the air. In addition, as the inhaled air passes through the nasal cavity, its temperature is brought close to that of the body, and it takes up water vapor so that it becomes more moist than before. • Pharynx is a common passage of digestive and respiratory system. Epiglottis, a flap like muscular valve controls movement of air and food towards their respective passages. • Larynx is a stiff box like structure containing our vocal cords. When air passes out of the lungs and over the vocal cords, it causes them to vibrate. This produces sounds on the basis of our speech, song etc. • Trachea is the wind pipe channeling air to lungs. • At its lower end the trachea or the wind pipe divides into two bronchi-one leading to each lung. • The bronchi divide into smaller and smaller branches called bronchioles. • These finally terminate in clusters of air sacs called alveolus in the lungs which are very small and numerous. Gaseous exchange takes place here as blood capillaries take up oxygen and expel carbon dioxide here. • Aerobic respiration occurs in adequate supply of air producing a lot of energy, carbon dioxide and water. • Anaerobic respiration and fermentation occurs in inadequate supply or absence of oxygen to produce energy. • Cells may resort to the breakdown of 3 carbon compound, pyruvate, aerobically or anaerobically depending upon the availability of oxygen. Usually in multicellular organisms cells fail to carry on the process of anaerobic respiration for long. • Respiration is not essentially a process of combustion differ due to following reasons - Glucose must be burnt at high temperature in the laboratory to liberate energy, if it happened in our cells, all cells would be burnt. - Once glucose starts burning we can’t stop the process easily, but living cells are able to exercise control over the sort of burning of glucose in the presence of oxygen. - Water normally stops combustion from taking place while cells contain a lot of water and respiration still goes on. • • Photosynthesis and respiration appear to be opposing reactions, but both have very different biochemical pathways and are essential for a plant’s metabolism. Photosynthesis takes place in the chloroplast to produce sugars, starches and other carbohydrates for the plant’s metabolic needs. • Cellular respiration occurs in mitochondria where mainly

these carbohydrates are “burned” to produce chemical energy to do work at the cellular level. 44 X Class Respiration - The energy releasing system Improve your learning 1. Distinguish between (AS1) a) inspiration and expiration b) aerobic and anaerobic respiration c) respiration and combustion d) photosynthesis and respiration 2. State two similarities between aerobic and anaerobic respiration.(AS1) 3. Food sometimes enters the wind pipe and causes choking. How does it happen?(AS1) 4. Why does the rate of breathing increase while walking uphill at a normal pace in the mountains? Give two reasons.(AS1) 5. Air leaves the tiny sacs in the lungs to pass into capillaries. What modification is needed in the statement?(AS1) 6. Plants photosynthesize during daytime and respire during the night. Do you agree to this statement? Why? Why not?(AS1) 7. Why does a deep sea diver carry oxygen cylinder on her back?(AS1) 8. How are alveoli designed to maximize the exchange of gases?(AS1) 9. Where will the release of energy from glucose in respiration take place? Mala writes lungs while Jiya writes muscles. Who is correct and why?(AS1) 10. What is the role of epiglottis and diaphragm in respiration?(AS1) 11. How gases exchange takes place at blood level?(AS1) 12. Explain the mechanism of gasses exchange at branchiole level.(AS1) 13. After a vigorous excercise or work we feel pain muscles. What is the relationship between pain and respiration?(AS1) 14. Raju said stem also respire along with leaves in plants. Can you support this statement? Give your reasons.(AS1) 15. What happen if diaphragm is not there in the body?(AS2) 16. If you have a chance to meet pulmonologist what questions your going to clarify about pulmonory respiration?(AS2) 17. What procedure you followed to understand anaerobic respiration in your school laboratory?(AS3) 18. What are your observations in combustion of sugar activity?(AS3) 19. Collect information about cutaneous respiration in frog. Prepare a note and display them in your classroom.(AS4) 20. Collect information about respiratory diseases (because of pollution, tobacco

) and discuss with your classmates.(AS4) 21. What is the pathway taken by air in the respiratory system? Illustrate with a labelled diagram.(AS5) 22. Draw a block diagram showing events in respiration. Write what you understood about cellular respiration.(AS5) Free distribution by A.P. Government 45 23. How you appreciate the mechanism of respiration in our body?(AS6) 24. Prepare an article on enaerobic respiration to present school symposium.(AS7) 25. Prepare a cartoon on discussion between haemoglobin and chlorophyll about respiration.(AS7) Fill in the blanks 1. Exhaled air contains _________ and _________. 2. A flap like muscular valve controls movement of air and food is ___________. 3. Energy currency of the cell is called _____________. 4. Lenticells are the respiratory organs exists in __________ part of plant. 5. Mangroove trees respire with their ____________. Choose the correct answer 1. We will find vocal cords in a) larynx b) pharynx c) nasal cavity d) trachea 2. Cluster of air sacs in lungs are called a) alveolus b) bronchi c) braonchioles d) air spaces 3. Which of the following is correct a) the diaphragm contracts - volume of chest cavity increased b) the diaphragm contracts - volume of chest cavity decreased c) the diaphragm expands - volume of chest cavity increased d) the diaphragm expands - volume of chest cavity decreased 4. Respiration is a catabolic process because of a) breakdown of complex food molecules b) conversion of light energy c) synthesis of chemical energy d) energy storage 5. Energy is stored in a) nucleus b) mitochondria c) ribosomes d) cell wall ( ( ( ( ( ) ) ) ) ) 46 X Class Respiration - The energy releasing system Annexure Pranayama - The art of breathing It is wonder to know that only human beings have to learn how to breath. Our lungs are devided into lobes. At each breath we will inhale or exhale only 500ml of air. Where as our lung capacity is approximately 5800ml. So most of the time breathing takes place in the upper lobes only. This means we are not using our lungs to their fullest capacity. Even after complete expiration approximately 1200ml

of air remains in our lungs. So we can make use of 4600ml of lung capacity for breathing. The indian ayurvedic physician. Patanjali developed a scientific breathing practice called Yogabyasa. Maharshi Patanjali proposed a theory called Astanga yoga. He was introduced 195 yogic principles in eight divisions. 1. Yama (Social disipline), 2. Niyama (Individual disipline), 3. Asana (Body posture), 4. Pranayama (Expansion of vital energy), 5. Prathyahara (With drawal of senses), 6. Dharana (Consontration), 7. Dhyana (Meditation), 8. Samadi (Self rialisation). The art of breathing in Yogabyasa is called Pranayama prana means gas, ayama means journey. In Pranayama practice air is allowed to enter three lobes of lungs inorder to increase the amount of oxygen to defuse into blood. Deep breaths in Pranayama helps us to reduce breathings per minute form 20-22 to 15. Because of these deep breaths more amount of oxygen available to brain and tissues of the body will be more active. It is very important to practice Pranayama regularly to make our life healthy and active. All people irrespective of age and sex should practice Pranayama under the guidance of well trained Yoga Teacher to improve the working capacity of lungs. Free distribution by A.P. Government 47 Chapter 3 Transportation - The circulatory system All the living organisms need nutrients, gases, liquids etc., for growth and maintenance of the body. All the organisms would need to send these materials to all parts of their body whether they are unicellular organisms or multicellular. In unicellular organisms these may not have to be transported to longer distances while in multicellular forms have to be sent substances to long distances as far as say over 100 feet for the tallest plant on earth. In lower organisms like amoeba, hydra etc., all the materials are transported through a simple processes like diffusion, osmosis etc., In higher animals with trillions of cells in their body adopt the method of diffusion and osmosis only for the bulk movement of materials, would takes years. To avoid delay a separate system is needed to carry the materials much faster and more efficiently. This specialized system that is developed by organisms is called ‘the circulatory system’. We eat solids, we

drink liquids, and we breathe gases. Do you think that it is possible to transport all the three types of materials, through a single system? Let us study how this circulation is carried out in our body. Have you ever observed a doctor holding the wrist of the patient and looking at his watch for a minute? What is that he is trying to find out from the watch and the wrist of the patient? You may wonder to know that he is 48 X Class Transportation - The circulatory system counting the heart beat of the patient. Don’t you think that is crazy, holding the hand to count the heart beat? Activity-1 You could try to find out for yourself, what the doctor was doing. Keep your index and middle fingers on your wrist below the thumb as shown in the fig-1. • What did you feel? You feel something pushing your fingers rhythmically up and down. Now let us count the rhythm which is called the pulse, for a minute. Now stand up and jog for one minute at the same place. Note the pulse for a minute. Take readings atleast two of your parents in the same manner and record in the following table. fig-1: Pulse S.No Name of the person Table-1 Pulse rate per minute at rest after jogging • What did you observe? Is the pulse rate same in both conditions? Activity-2 We see that pulse rate varies from person to person and situation to situation. So it is not constant, when you are afraid or excited the pulse rate goes up. Observe your pulse rhythm in other ways as well such as climbing stairs, running, etc. There is a relationship between the pulse rate and the beat of our heart. Now let us try to find out more about this relationship. fig-2: Matchstick stethoscope For this you have to make your own stethescope. Take a shirt button insert a matchstick as shown in fig-2. Place it on your wrist. Observe movements in matchstick. • What did you find? • When do you think that our pulse rate goes up? • What does the pulse rate show? Free distribution by A.P. Government 49 Do you know? Newborn (0–3 months) Infants (3-6 months) Infants (6–12 months) Children (1-10 years) Children over 10 years & adults, including senior citizens Welltrainedadults athletes 100-150 90-120 80-120 70-130 60-100 40

-60 In the year 1816, Rene Laennac discovered the Stethoscope. Before the discovery of stethoscope doctors used to hear heart beat by keeping ear on the chest of the patient. Laennac found that paper tube helps to hear the heart beat perfectly. Then he used a bamboo instead of paper tube to hear heart beat. Laennac called it stethoscope. Activity-3 Let us repeat the work Laennac. Make a paper tube 10 inch long and one inch in diameter. Keep one end of it on the chest of your friend on a point one inch to the left side to the centre around 6 inches below from his or her neck. Keep your ear at the other end. Listen carefully and count the heart beats for a minute. Also count down your friend’s pulse rate. Note observations of at least 10 students of your class in the following tabular form. Table-2 S.No Name of the student Eswar 1 Heart beat at rest/min Pulse rate at rest/min 72 72 Let us plot histogram on heart beat and pulse rate of different persons as shown in the sample graph. Here blue bar indicates heart beat, red bar indicates pulse rate. • What is the relationship between the heart beat and the pulse? • Can we say, the pulse rate is always equal to the heart beat? You might have studied there is a relation between pulse rate and heart beat. Eshwar x-axis: Name of the student y-axis: Heart beat, pulse rate per minute 50 X Class Transportation - The circulatory system Now try to understand the structure and method of working of this vital organ, the heart. It is the beat of the heart which keeps us alive. Heart is located in between the lungs and protected by rib cage. The size of your heart is approximately the size of your fist. fig-3: Location of Heart fig-4: Heart Lab Activity Aim: Observation of the internal structure of the mammalian heart. Material required: Since the structure of all the mammalian hearts are similar, we take the sheep’s or goat’s heart for our observation. For this, we need following materials. Freshly collected specimen of heart of sheep or goat from the butcher. Soda straws, sharp and long blade or scalpel, tray, a jug of water, Dissection scissors, forceps. Procedure for observation: • Before coming to the class wash the heart thoroughly so that, blood is completely drained from the chambers of heart.

• Take soda straws and insert them into the stumps of the blood vessels. Note your observations as you proceed. • How many layers are covering the heart? (Now remove the layers covering the heart, and observe) • What is the shape of the heart? • How many large blood vessel stumps are attached to the heart? • Which end of the heart is broader and which end is narrow? Observe the arrangement of blood vessels (coronary vessels) on the wall of the heart. (In case you don’t have a model or a goat’s heart, look at the figures given carefully for observation) Free distribution by A.P. Government 51 Internal structure of the heart • Keep the heart in the tray in such a way that a large arch like tube faces upwards. This is the ventral side. • Now take a sharp blade or scalpel and open the heart in such a way that the chambers are exposed. Take the help of the fig-6. arteries to head artery to left arm superior vena cava aorta pulmonary artery (right branch) right pulmonary veins right atrium right atrio vetricular valve pulmonary artery (left branch) left pulmonary veins left atrium semi - lunar valve in the pulmonary artery left atrio vetricular value left ventricle inferior vena cava right ventricle fig-5: Internal structure of heart Now observe the internal structure. Observe the wall of the heart. Is the thickness of the wall of the heart uniform throughout? • • How many chambers are there in the heart? • Are all the chambers of the same size? • What other differences could you observe between the chambers? • Are all the chambers connected to each other? • How are they connected to each other? How are they separated? You can observe white coloured structures in the lower part of the heart. Note down the size, shape and to which parts they are attached. Can you guess the function of these structures? Write a note on your observations of the heart. Compare your notes with the description given below. The heart is a pear shaped structure, triangle in outline, wider at the anterior end and narrower at the posterior end. The heart is covered by two layers of membranes. The membranes are called pericardial membranes. The space between these two layers is filled with pericardial fluid, which protects the heart from shocks. 52 X Class Transportation - The circulatory system The heart is divided into four parts by grooves. Two upper

parts are called atria (auricles), and the lower ones are called ventricles. The left atrium and ventricle are smaller when compared to that of right atrium and ventricle. The blood vessels found in the walls of the heart are coronary vessels which supply blood to the muscles of the heart. The walls of the ventricles are relatively thicker than atrial walls. In our observation we found that the heart has four chambers in it. On the left side two chambers are present, one is anterior and the other is the posterior. On the right side also two chambers present, one upper (anterior), and one lower (posterior). Observe the presence o blood vessels attached to the heart. • How many blood vessels are attached to the heart? • Are all the blood vessels are rigid? How many of them are rigid? • Do you think that the stiffness/rigidity of blood vessel is something to do with circulation? The rigid vessels are called arteries which originate from the heart and supply blood to various organs in the body. The larger artery is the aorta. The relatively smaller one is pulmonary artery which carries blood from the heart to the lungs. The less rigid vessels are the veins, which bring blood from all body parts to the heart. The vein which is at the anterior end of the right side of the heart is superior venacava (precaval vein), which collects blood from anterior parts of the body. The vein which is coming from posterior part of the heart is inferior venacava (postcaval vein), collecting blood from posterior part of the body. The two atria and the two ventricles are separated from each other by muscular partitions called septa. The openings between atria and ventricles are guarded by valves. In the right atrium we can observe the openings of superior and inferior venacava. In the left atrium, we can observe the openings of pulmonary veins, that bring blood from lungs. From the upper part of the left ventricle, a thick blood vessel called aorta arises. It supplies oxygenated blood to the body parts. From the upper Free distribution by A.P. Government 53 part of the right ventricle pulmonary artery arises that supplies deoxygenated blood to the lungs. After careful examination we can observe valves in the pulmonary artery and aorta as well. The blood vessels and circulation Let us study how we came to know about the structure and functions of the blood vessels. It was not

until 16th century that we really came to know how our blood vessels functioned. In 1574, an Italian doctor, Girolamo Fabrici, was studying the veins in the leg. He noticed that they had small valves in them. If the blood moved in one direction, the valves folded towards the walls of the vessel, so that the blood could pass without trouble. If the blood moved in the opposite direction, the valves closed. This meant they are one-way valves. The valves permitted the blood to move even when a person is standing upright. But not move downward. When a person moves his legs, or just tightens his leg muscles, those muscles squeeze the veins and force the blood in those veins to move upward against the pull of gravity (because that’s the only way to go). If a person keeps his leg muscles relaxed, the blood isn’t moving much, but at least it isn’t being pulled down by gravity. The valves won’t allow that. Everyone thought that the blood leaving the left ventricle always moved away from the heart for which Fabrici paid no attention. He missed the importance of his own discovery. But then, William Harvey (1578-1657), an Englishman who, after he became a doctor, went to Italy for further education and studied under Fabrici. Harvey dissected the hearts of dead people and studied the valves between each atrium and its ventricle. He noticed that they were oneway valves. They allowed the blood to flow from the atrium to the ventricle without any hinderance. When the heart contracted, however, no blood in the ventricle could flow back into the atrium. Instead, all the blood was pushed out into the arteries. Harvey began thinking about the valves his teacher, Fabrici, had discovered in the leg veins. They were one-way, and they forced the blood to move toward the heart. He checked that by tying off and blocking different veins in animals he experimented on the veins always bulged on the side of the block away fig-6: William Harvey 54 X Class Transportation - The circulatory system from the heart. As though the blood as trying to flow toward the heart and to accumulate just below the block because it simply couldn’t flow away from the heart. This was true of all veins. In the arteries, the blood bulged on the heart side of any block he put in, as though it were trying to flow away from the heart

and couldn’t move in the other direction. Harvey now saw what was happening. The heart pushed blood into the arteries, and the blood returned by way of the veins. It did this for both ventricles. The blood had a double circulation. If one started from the right ventricle, it left by way of the arteries to the lungs, and returned by way of the veins to the left atrium and from there into the left Ventricle.From the left ventricle, it left by way of the arteries to the rest of the body and returned (in a “greater circulation”) by way of the veins to the right atrium and from there into the right ventricle. Then it started all over. Harvey also showed that it was impossible, suppose that the blood was used up in the body and that new blood was formed. He measured how much blood the heart pumped in one contraction and also counted the number of contractions. He found that in one hour, the heart pumped out a quantity of blood that was three times the weight of a man. The body couldn’t use up blood and form new blood at such a rate. The same blood had to circulate and be used over and over again. Harvey still had some problem. The smallest arteries and veins that could be seen had to be connected by vessels too small to see. Were they really there? In the 1650s, scientists had learned to put lenses together in such a way that objects too small to see with the naked eye could be magnified and made visible. Marcello Malpighi (1628-1694), with the microscope, he could see tiny blood vessels that were invisible with naked eye. In 1661, four years after Harvey’s death, Malpighi studied the wings of bats. He could see blood vessels in their thin membranes and, under the microscope; he could see that the smallest arteries and veins were connected by very fine blood vessels. He called these blood vessels “capillaries” from the Latin word for “hair”, because they were as thin as the finest of hairs. With the discovery of capillaries, the idea of the circulation of the blood was complete, and it has been accepted ever since. fig-7: Marcello Malpighi Free distribution by A.P. Government 55 Now, we know that blood circulates in the blood vessels. But how did the scientists find out that blood

moves in blood vessels? Is it possible to demonstrate the movement of blood in vessels without damaging the vessels? Let us repeat the classical experiment to demonstrate the movement of blood in veins conducted by William Harvey in early 17th century, when there was no compound microscope or any other modern equipment. 1. Tie a tornquit just above the elbow of a person, whose blood vessels are prominent in the hand. 2. Ask him/her to hold the fist with a piece of cloth rolled in the hand. Now the blood vessels can be seen more prominently. 3. Find undivided blood vessel, where we have to work for the next few minutes. 4. At the end of the vessel farthest from the elbow apply steady pressure, so as to close its cavity. 5. Now apply pressure from elbow towards the palm slowly and observe the changes in the blood vessels. (Take the help of the figures given here.) Observe changes and discuss in your class. fig-8(a): Try like this fig-8(b): Harvey’s Arteries and veins There are two types of blood vessels called arteries and veins. Arteries carry blood from the heart to body parts. Whereas, veins carry blood from body organs to heart. Let us observe the structural and functional differences between arteries and veins. tough fibrous coat elastic fibrous coat muscle layer lumen lining cells lumen lining cells fig-9(a): T.S. of Artery fig-9(b): T.S. of Vein fig-9(c): T.S.of Blood capillary Blood capillaries Blood capillaries are the microscopic vessels made of single layer of cells. They allow diffusion of various substances. The leucocytes (WBC) can squeeze out of the capillary wall. They establish continuity between arteries and veins. 56 X Class Transportation - The circulatory system Answer the following after reading the experiment conducted by William Harvey. • In which blood vessels valves are found? What do you think is the function of the valves in them? • Why do sub-cutaneous blood vessels bulge on the side away from the heart when the hand is tied? • The deep seated blood vessels (the arteries) bulge on the side towards the heart when tied. What do you understand from it? • There are valves in the heart between atria and ventricles. Is the purpose of valves in the veins and arteries same? After reading the experiments by Harvey fill in the following table. Use

the clues/options given in the first column. Structure / Function Artery Vein Table-2 1. Thickness of walls(thick / thin) 2. Valves (present / absent) 3. Capacity to retain shape when blood is absent (can retain/collapse) 4. Direction of blood flow (heart to organs / body organs to heart) 5. Pressure in the vessel(low /high) 6. Type of blood transported (oxygenated / de-oxygenated) 7. Type of blood carried by pulmonary artery (de -oxygenated/ oxygenated) 8. Type of blood carried by pulmonary vein (oxygenated / de-oxygenated) Let us perform the following activities to observe arteries and veins. Sit on a table with one leg dangling and the other resting on it so that the back of one knee rests on the knee of the other. After a time you will see and feel the leg which is on top give a series of small movements with each heart beat. If you do it for long you will reduce the blood flow to the leg and so develop ‘pins and needles’. Swing your arm round several times to fill the veins with blood, hold the arm vertically downwards and gently press your finger along a prominent vein-stroking it in the reverse direction to the blood flow, i.e., towards the Free distribution by A.P. Government 57 hand. Can you see the swellings where you have pushed blood against the valves? Discuss with your teacher about reasons. Think and discuss • Artery walls are very strong and elastic. why? • Why we compare arteries like tree which devides into smaller and smaller branches. • The lumen size is bigger in vein when compared with artery. Why? The cardiac cycle The human heart starts beating around 21st day during the embryonic development (refer reproduction chapter). If it stops beating, it results in the death of a person. One contraction and one relaxation of atria and ventricles is called one cardiac cycle. 1. We start with the imagination that all the four chambers of the heart are in relaxed state (joint diastole). 2. Blood from venacava and pulmonary veins enters the right and left atria respectively. 3. Now the atria contract, forcing the blood to enter into the ventricles. 4. When the ventricles are filled with blood they start contracting and atria start relaxing. On ventricular contraction due to pressure the blood moves into the aort

a and pulmonary artery. The aperture between the atria and ventricles is closed by valves. When the valves are closed forcibly, we can listen to the first sharp sound of the heart lub. 5. When the ventricles start relaxing the pressure in the ventricles is reduced. The blood which has entered the arteries tries to come back into the ventricles. The valves which are present in the blood vessels are closed to prevent backward flow of blood into the ventricles. Now we can listen to a dull sound of the heart dub. The atria are filled up with blood and are ready to pump the blood into the ventricles. The sequential events in the heart which are cyclically Transportation - The circulatory system 1. Imaginary relaxation of atria and ventricles. 2. Blood flows into atria. 3. Contraction of atria and flow of blood into ventricles. 4. Contraction of ventricles. A.V. Valves closed (Lub) blood flows into artries. 58 X Class repeated are called cardiac cycle. The cardiac cycle includes an active phase systole and a resting phase the diastole of atria and ventricles. The whole process is completed in approximately 0.8 second. The time needed for atrial contraction is 0.11-0.14 seconds. The time needed for ventricular contraction is 0.27-0.35 seconds. Hence, naturally the blood is pumped into the blood vessels at regular intervals. The tissues will not receive the blood continuously, but in the form of spurts. When we keep our finger at the wrist, where the artery is passing into the hand we feel the pressure of blood moving in it. This is the pulse. The rate of the pulse will be equal to the number of heart beats. Do you know? 5. Relaxation of ventricles. The closing of arterial valves (Dub). fig-10(1-5): Cardiac cycle Name of the animal Blue whale Elephant Man Coaltit (Bird) Weight of the body Weight of the heart 1,50,000 kg 3000 kg 60-70kg 8 gm 750 kg 12 - 21 kg 300 gm 0.15 gm No. of beats/min 7 46 76 1200 Single /double circulation We know that blood flows in the blood vessels. To keep the blood moving the heart pumps it continuously. The blood that is pumped by the heart reaches the body parts and comes back to the heart.

But course taken by the blood is not the same in all the animals. Let us observe the fig11(a) and (b). Start from any point in the fig-11(a) and (b). Move in the direction of arrow. Note down the parts which are in the way in cyclical form. (Try to identify different parts of the body in both figures.) Free distribution by A.P. Government fig-11(a): Single circulation fig-11(b): Double circulation 59 Compare the two flow charts and answer the following. • How many times did your pointer touch body parts in fig-11(a) and (b)? • How many times did your pointer touch the heart in fig-11(a) and (b)? • How many times did your pointer touch the respiratory organs in fig-11(a) and (b)? From your observation it is clear that in fig -11(a) blood flows through heart only once to complete one circulation. If blood flows through heart only once for completing one circulation it is called single circulation. If the blood flows through the heart twice for completing one circulation it is called double circulation. Lymphatic system As blood flows through tissues some amount of fluids and certain solid materials are constantly flowing out of them at different junctions. Such materials are to be collected and sent back into blood circulation. Have you ever observed what happened to your feet after overnight journey, in sitting position without moving? We feel that our foot wear is little tight. In elders it will be clear that the lower part of the legs will be swollen. This stage is called edema. • Why do our legs swell? We know that blood circulates in the blood vessels, pushed by the heart. From the heart it flows into the arteries and finally into the capillaries. To supply nutrients to the cells (tissues), the liquid portion of the blood with nutrients flows out of the capillaries. This is called tissue fluid. The tissue fluid which is present in the tissues should be transported into the blood vessels again. Some portion of the tissue fluid enters into the venules, which in turn form the veins, which carry blood to the heart. What about the remaining tissue fluid? To transport the tissue fluid in to the main blood stream, a separate system is present. That is called lymphatic system. In latin lymph means water. Lymph is the vital link between blood and tissues by which essential substances pass from blood to cells and excretory products from cells

to blood. The lymphatic system is a parallel system to venous system which collects tissue fluid from tissues and transports it to the venous system. Blood is a substance which contains solid and liquid particles. Transportation - The circulatory system fig-12: Lymphatic system 60 X Class Lymph is the substance that contains blood without solid particles. Tissue fluid is lymph present in the tissues. The liquid portion after formation of blood clot is serum. The muscles which are attached to the skeleton (skeletal muscles) act as pumps when they contract and help in pushing the lymph flowing in lymphatic vessels and the blood flowing in veins towards the heart. The valves that are present in the lymphatic vessels and veins stop the reverse flow of blood. We shall read about this as the system of lymph circulation in detail in higher classes. Evolution of the transport (circulatory) system When the unicellular organisms separated themselves from the sea with the formation of the limiting membrane, the problem of transportation arose. The nature has found the solution, by creating a microscopic ocean which has its own currents. In unicellular organisms like Amoeba the protoplasm shows natural movements. These movements are called Brownian movements, because of which the nutrients and oxygen are distributed throughout the protoplasm equally. This simplest intracellular transportation system, present in unicellular animals has been retained in multicellular animals including humans. The protoplasm of any cell in our body is mobile and protoplasmic currents exist even in the nerve cells. The multicellular animals have to develop more complicated system for transportation of materials. The parazoas like sponges, use sea water for transportation. Since the natural water currents are not reliable, the sponges create their own currents by beating of flagella that are present in their body. The cnidarians which are better evolved than sponges (e.g. Hydra and jelly fish) have developed blind sac like gastrovascular cavity, which has taken up the function of digestion and transportation of nutrients to each and every cell of the body. In platyhelmenthes (e.g. Fasciola hepatica), the digestive system is highly branched and supplies digested food to all the cells directly. In these animals the excretory system collects wastes from each cell individually. In these organisms most of the body is occupied by digestive and excretory systems. In animals belonging to Nematyhelmenthes, the pseudocoel

om has taken up the function of collection and distribution of materials. Free distribution by A.P. Government 61 The Annelids, the first Eucoelomate animals have developed a pulsatile vessel, to move the fluid and the transporting medium is blood. The Arthropods have developed a pulsatile organ to pump the blood, the heart. The blood instead of flowing in blood vessels floods the tissues, directly supplying the nutrients to the tissues. Oxygen is directly supplied to the tissues directly by the respiratory system. Such type of transportation system which supplies nutrients to the tissues directly is called open type of circulatory system.eg. Arthropods, many molluscs and lower chordates. The other type of transportation system where the blood takes the responsibility of delivering the materials, which flows in the blood vessels is called closed type of circulatory system. Such type of closed circulatory system is present in annelids echinoderms, cephalopod molluscs (e.g. Octopus) and all the higher animals. Do you know? The human circulatory system can move one ml of blood from heart to a foot and back which is approximately 2 meters, in about 60 seconds. It would take more than 60 years for the substance to move across this distance by diffusion. Blood pressure (B.P.) In class 9th we studied about blood and it’s components, blood grouping, etc., in the chapter animal tissues. Now we will discuss some other points related to blood. Generally you have heard the word B.P. What is B.P.? To move the blood through this network of vessels, a great deal of force is required. The force is provided by the heart and is at its highest when the ventricles contract, forcing the blood out of the heart and into the arteries. Then there is a drop in the pressure as the ventricles refill with blood for the next beat. B.P. is always measured in the upper arm artery. B.P. varies throughout the body, so a standard place must be used so that a person’s blood pressure can be compared over a period of time. Doctors measure the blood pressure (B.P.) with a device called sphygmomanometer. There are two pressure readings. One measures the strongest pressure during the time blood is forced out of the ventricles. This is called systolic pressure. For a healthy fig-13: Sphygmomanometer 62 X

Class Transportation - The circulatory system young adult it will be 120 mm of Hg. The second reading is taken during the resting period, as the ventricles refill with blood. This is called diastolic pressure. It will be 80 mm of Hg. B.P. will change according to the activity in which the person is engaged, such as resting, walking and running. People who have high B.P. during resting period are said to have hypertension. Discuss with your teacher about low blood pressure. Coagulation of blood Another important part in the story of blood is coagulation. Only because of this character animals survive when they meet severe injuries. When there is an injury blood clots in 3-6 minutes. How does the blood clot? What chemistry involved in blood coagulation. You know that when you cut yourself, the blood flows out of the wound for only a short time. Then the cut is filled with a reddish solid material. This solid is called a blood clot. If blood did not clot, anyone with even a slight wound bleeds profusely. • When the blood flows out, the platelets release an enzyme called thrombokinase. • Thrombokinase acts on another substance present in the blood called pro-thrombin converting it into thrombin. • Thrombin acts on another substance called fibrin, that is present in dissolved state converting it into insoluble fibrin. • The blood cells entangle in the fibrin fibers forming the clot. • The fibrin fibers are attached to the edges of the wound and pull them together. This straw yellowish coloured fluid portion after formation of the clot is serum. Discuss with your teacher about vitamin K in relation to coagulation of blood. fig-14(a): Blood in the blood vessel fig-14(b): Clot formation Free distribution by A.P. Government 63 Normally the blood that oozes from a wound clots in 3-6 minutes. But in some people due to vitamin K deficiency it takes more time. Because of genetic disorder the blood may not coagulate. This type of disorder is called haemophilia. Haemophilia is common disorder in the children who have born from marriages between very close relatives. Thalassemia an inherited disorder is also related to blood. For more details see annexure. HOW MATERIALS TRANSPORT WITH IN THE PLANT There is a vast transport system in continual supply of

essential nutrients and oxygen to perform metabolic activities, and to remove excretory substances which are found in each cell of animal body. Is there anything like that in plants which corresponds to circulatory system? In previous classes we studied about Van Helmont’s experiments on plants, which get water that contain minerals from soil through their roots. The water absorbed by roots and food prepared by leaves are supplied to the remaining parts of the plant by vascular bundles having xylem and phloem. In the root the xylem tissue is situated towards the exterior while in the stem it is arranged in bundles towards the center. fig-15: Transportation How is water absorbed? We know that roots absorb water with minerals from soil. • What is the mechanism behind this? • Are roots directly in contact with water? • How is water absorbed? Activity-4 Absorving root hairs To perform this activity, you need to germinate bajra or mustard seeds. Examine some mustard seedlings which have been grown on wet filter paper. Observe the mass of fine threads coming from the seed by hand lens. These are roots. They have fine microscopic structures called root hairs. These are root hairs trough which water enters the plant. Gently squash a portion of the root hair between slide and cover slip in a drop of water and examine under a microscope. Note the thinness of the walls of root hairs. It is not completely understood how the water enters the root 64 X Class Transportation - The circulatory system hairs and passes inwards from cell to cell until it gets into the xylem vessels, but there is no doubt that osmosis plays an important role. Every living cell acts as an osmotic system, the cytoplasm lining of the cell wall acts as the semipermeable membrane. Observe the following figure, notice how do roots penetrate into soil? You will find that the root hairs grow out into the spaces between the soil particles and that the hairs are surrounded by moisture. xylem vessel cells of cortex epidermal cell soil particles soil water nucleus air spaces cell wall of root hair cytoplasm vacuole fig-16: L.S of root showing relationship of root hair and soil water Note: In fig-16 Arrow marks shows the direction of flow of water. The soil water is an extremely dilute solution of salts, water molecular concentration is more dilute than that of the cell sap in the root hair; therefore water will pass into the vacuole of the

root hair by osmosis. Recall the process of osmosis that you have learnt in the chapter “moving of substances through plasma membrane” in class IX. The entry of water dilutes the contents of the root hair vacuole so that it becomes more dilute than it’s neighbouring cell. So, water passes into the neighbouring cell which in turn becomes diluted, finally water enters the xylem vessels. As there are vast number of root hairs and root cells involved, a pressure in the xylem vessels develops which forces the water upwards. This total pressure is known as root pressure. Root pressure is not the main cause of movement of water in xylem but it is certainly one of the factor. The other factors are also there. You will learn about those reasons in higher classes in detail. Activity-5 What is root pressure Take a regularly watered potted plant and cut the stem portion 1 cm above the ground level. Then connect a glass tube by means of strong rubber Free distribution by A.P. Government 65 clamp glass tube water level strong rubber tubing cut stem portion soil tubing as shown in the figure. The size of glass tube should be equal to the size of the stem. Take care while joining tube and stem being bound tightly, so that water cannot escape from the tube. Now, pour some water in the glass tube until water level can be seen above the rubber tube. Mark the level of water (M1) in the tube. Keep your arrangement aside for 2 to 3 hours. Then observe and mark the water level (M2) in the tube. Is there any increase in the water level? • • What is the role of xylem in this action? The difference between M2 and M-1 indicates the level of water raised in the stem. Because of the root pressure, the water level increases in the tube. water fig-17: Root pressure The mechanism by which the water travels through the plant We have seen that there is a push from below due to root pressure on the columns of water in the xylem vessels, but this is seldom high and in some seasons it is nil. How does the water reach 180 metres high to the top of a tree like a eucalyptus? Let us recall the activity that you performed in lower classes. Why inner sides of cover become moist? Where do these water droplets or water vapour come from? We know that this type of evaporation of water through leaves is called transpiration. Water

evaporates through stomata of leaves and lenticels of stem. When the leaves transpire, there is a pulling effect on the continuous columns of water in the xylem vessels. The top ends of these vessels are surrounded by the leaf’s mesophyll cells which contain cell sap, so the water is continuous from the xylem vessels to the walls of the mesophyll cells from which it evaporates into the air spaces causing the pull. The water column does not break because of its continuous molecular atraction. This is a property of water you demonstrate every time you drink through a straw. Now we have a picture of the water-conducting system of a tree. Water is absorbed by osmosis from the soil by Transportation - The circulatory system fig-18: Transpiration 66 X Class the root hairs. This is passed into the xylem vessels which form a continuous system of tubes through root and stem into the leaves. Here the water evaporates and releases into the atmosphere. The evaporation creates the main pull of water above root pressure which gives a variable and minor push from below. This results in a continuous column of moving water, the ‘transpiration stream’. Is there any relation between transpiration and rain fall? The amount of water passing through a plant is often considerable. For example, an oak tree can transpire as much as 900 liters of water per day. It follows therefore that areas of forest significantly affect the degree of saturation of the air above them, so that when air currents bring air which is already nearly saturated to a forest area, it becomes fully saturated and comes down as rain; this is why forest areas often have a higher rainfall than areas nearby. Do you know? How much water is transpired by plants? Each fully grown maize plant transpires 15 liters per week. One acre of maize may transpires more than 13,25,000 liters of water in a hundred day growing season. A big mango tree will transpire from 750 to more than 3500 liters of water per day during growing season. Transport of mineral salts You know that mineral salts are necessary for plant nutrition (micro and macro nutrients) and that they are obtained from the soil solution through the root hairs. The salts are in the form of electrically charged ions. Sodium chloride (NaCl) is in the form of Na+ and Cl-, and Magnesium 2-. But, they are not absorbed Sulphate (MgS04) occurs as M

g2+ and S04 into the root hairs by the simple process of diffusion, but it involves the use of energy by the cytoplasm which will be discussed in later classes. Once ions are absorbed, the ions travel along with water in the xylem vessels and pass to the growing points of the plants where they are used for growth purpose. They may also pass laterally from xylem to phloem. Thus, mineral salts are one of the natural factors in plant growth phenomena. Transport of manufactured food Food such as sugar is synthesised in the green parts of plants, mainly the leaves, but this food has to be transported to all the living cells, especially to actively growing cells and the cells which stores food. Free distribution by A.P. Government 67 proboscis The veins of a leaf consist of xylem and phloem, and these tissues are continuous with the stem. The following experiments provide evidence that food is transported in the phloem cells. fig-19: Aphid extracting food material from plant aphid xylem phloem Phloem sieve tubes are extremely small and the analysis of their contents is not easy. Biologists studied about food transportation in plants with the help of aphids (greenfly). When you see aphids clustering round the young stems of plants as they feed on the plant juices. To obtain this juice an aphid pierces the plant tissues with its long needle like organ “proboscis”. It can be shown when a feeding aphid is killed and the stem carefully sectioned, the proboscis only penetrates upto a phloem sieve tube. This proboscis also provides a ready-made means of obtaining the juice for analysis! The experiment can be done in this way. An aphid is killed while in the act of feeding and the body is then carefully cut away, leaving the hollow proboscis still inserted into the phloem. It is found that because the contents of the phloem sieve tubes are under slight pressure the fluid slowly exudes from the cut end of the proboscis in the form of drops; these drops are then collected and analysed. The fluid is found to contain sugars and amino acids. Not surprisingly, aphids absorb so much sugar from the phloem that they cannot assimilate all of it and it excretes out of the out of the body as a sticky syrup called honey dew. Leaves which have been attacked by aphids often

feel sticky as a result of honey dew. some growth no growth fig-20: Removing ring of bark You may notice that sometimes barks of the tree damaged more than a half, even then the tree is alive. How is this possible? Further experiments to illustrate the conduction of sugars by the phloem have been done by removing a ring of bark from a shoot to expose the wood. Remove all tissues from the center outwards, including the phloem. After a few days, when the tissues above and below the ring were analyzed it was shown that food had accumulated above the ring, but was not present below it. If it is left for some more time, the stem increases in thickness immediately above the ring, but no growth occurred 68 X Class Transportation - The circulatory system below it. So, any damage to the phloem all around the stem will prevent the food from passing down to the roots and the tree will eventually die. This is a fact of great economic importance because certain mammals scratching the bark of trees to get the food stored in the phloem, especially during hard winters when food is scarce. Voles do this to young saplings at ground level and rabbits can do much damage to older ones. Foresters find it economically worthwhile to enclose new plantations with wire netting to prevent rabbits from entering. Foresters also encourage predators such as foxes, badgers, hawks and owls as they help to keep down the population of voles and rabbits. Grey squirrels too do great damage, particularly to beech and sycamore, and for this reason, in some parts it is impossible to grow these trees as a crop. Observe barks of trees in your surroundings for evidence of bark having been gnawed off saplings and trees. Note the species of tree, the position of the damage, whether the damage is recent or old, and the size of tooth marks if these are visible. From these observations you could find out which species had caused the damage. Also look out for the effect of such damage on the tree as a whole. Key words Circulation, Right atrium, Left atrium, Right ventricle the lower right chamber of the heart, Left ventricle, Pulse, Artery, Vein, Stethoscope, Aorta, Capillary, Systole, Diastole, Cardiac cycle, Blood pressure, Lymph, Single circulation, Double circulation, Coagulation of blood, Sphygmomanometer, Pro

thrombin, Thrombin, Fibrinogen, Fibrin, Root hair, Radical, Root pressure, Plant nutrients, Xylem, Phloem, Vascular bundles. What we have learnt • The pulse rate is equal to heart beat. We can count the heart beat without the aid of any instrument. • Rene Lennac discovered the first stethescope. • The heart is covered with two pericardial membranes filled with pericardial fluid which protects it from shocks. • Six blood vessels are attached to the heart. The two rigid blood vessels are arteries which supply blood to body parts aorta and lungs and pulmonary artery. • The less rigid vessels are various, which bring is blood from body parts. • Heart has four chambers, two upper atria and two lower ventricles. • Atrium and ventricle of the same side are connected by atrium ventricular aperture. • Atria are separated from each other by interatrial septum, ventricles by interventricular septum. Free distribution by A.P. Government 69 • The atrioventricular apertures are guarded by valves. There are valves in the aorta and pulmonary artery also. • The right side of heart receives blood from body and sends to lungs. • The left side of the body receives blood from lungs and send it to body parts. • The arteries carry oxygenated blood except pulmonary artery. The veins carry deoxygenated blood except pulmonary veins. • One contraction and relaxation of heart is called cardiac cycle. • If the blood goes to heart only once before it reaches all the body parts. It is called single circulation. If it goes twice it is called double circulation. • Vitamin K deficiency leads to delayed coagulation of blood. • Plants absorb soil water through roots by the process of osmosis. • Water travels through xylem vessels and food material travels through phloem tissues. • There is a relation between tranportation and transpiration in plants. • Biologists studied about phloem tubes with the help of aphids. Improve your learning 1. What is transport system? How this helps to the organism?(AS1) 2. What is the relationship between blood and plasma?(AS1) 3. Which type of blood vessels carry blood away from the heart?(AS1) 4. What are the three main types of blood vessels in the body?(AS1) 5. Which is the

largest artery in the body? Why is it big in size?(AS1) 6. Which blood vessel carries blood for oxygenation?(AS1) 7. Name the structures which are present in veins and lymph ducts and absent in arteries.(AS1) 8. What is the use of platelets?(AS1) 9. Write differences betweenm(AS1) a) systole - diastole b) veins - arteries c) xylem - phloem 10. Explain the way how plants get water by osmosis through root hair?(AS1) 11. What is root pressure? How it is useful to the plant?(AS1) 12. Phloem is a food source for some animals. How can you justify this statement?(AS1) 13. Read the given para and name the parts of the heart.(AS1) We have observed that the heart is divided into four chambers by muscular structure. Any structure that divides two chambers is known as septum. Now let us try to name the septa present in the heart. a) The septum that divides the two atria can be named as inter atrial septum 70 X Class Transportation - The circulatory system b) The septum that divides the two ventricles can be named as___________. c) The septum that divides the atrium and ventricle can be named as________. The holes that connect two chambers are called apertures. Let us try to name the apertures which connect the atria and ventricles. d) The aperture that is connecting the right atrium and right ventricle can be named as_______. e) The aperture that is connecting the left atrium and left ventricle can be named ___________. Any structure that closes an aperture, and allows one way movement of materials is called as valve. Now let us name the valves that are present in the chambers of the heart. f) The valve that is present between left atrium and left ventricle can be named as____________. g) The valve that is present between right atrium and right ventricle can be named as ___________. 14. If the valves in veins of the legs fail to stop the flow of blood what could be the consequences of this failure?(AS2) 15. What will happen if cell sap of root hair cells contain high concentration of ions?(AS2) 16. John prepared

stethoscope with paper cup and plastic tube. Write down the procedure of preparation. (AS3) 17. How can you prove that the water is transported through the xylem?(AS3) 18. What is your inference about experiments with aphids?(AS3) 19. Collect information about blood pressure of your school teachers or your nighbours prepare a report on their help problems. (AS4) 20. Draw a block diagram to explain single and double circulation. Write differences between them.(AS5) 21. Prepare a block diagram showing from water absorption by roots to transpiration by leaf. (AS5) 22. What do you want to compare with the transportation in blood vessels? (AS6) 23. How do you feel about transportation of water in huge trees? (AS6) 24. Prepare a cartoon on heart beating? (AS7) 25. After reading this lesson what precautions you would suggest to your elders about edima.(AS7) Choose the correct answer 1. The term cardiac refers to which organ in the body? a) heart b) vein c) lymph d) capillary 2. On which side of the human heart is low in oxygen? a) left vetricle b) right ventricle c) left atrium d) right atrium 3. Which structures of the heart control the flow of the blood? a) arteries b) veins c) valves d) capillaries ( ( ( Free distribution by A.P. Government ) ) ) 71 4. Which of the following opinion is correct? ( ) a) Ravi said, xylem and phloem cells arranged one upon the other to form a tube like structure. b) John said, xylem and phloem are not separate tube like structures. c) Salma said, xylem and phloem cells connect together to form a tube like structure. d) Hari said, because of its shape they said to be tube like structures 5. An aphid pierces its proboscis into the ……… to get plant juices ( ) a) Xylem b) phloem c) cambium d) vascular bundle Annexure-I The rhesus factor There is another antigen of red blood cells which is present in 85% of the people of Britain, this is known as the rhesus factor, as it was first discovered in rhesus monkeys. People who have this are said to be rhesus positive (Rh

+). Those who do not have this factor are termed rhesus negative (Rh-). Normally they do not carry an antibody to this factor in their plasma. However, if Rh+ blood is transfused into the blood of a Rh- person, antibodies will be formed and these are capable of destroying Rh+ red cells. Under certain circumstances this is a potential hazard for babies. If a Rh+ man marries a Rh- woman, some of the children are likely to be Rh+. At birth there is always some mixing of blood between the circulation of mother and baby and this may occasionally happen during pregnancy. So, if a child is Rh+ some of its blood will leak into its mother’s circulation and cause antibodies to form in her blood. If the mother has more children, not all will necessarily be Rh+, but if they are, the amount of ant bodies in her blood often increases with each pregnancy, and in some instances the antibodies in her blood may pass into the baby’s blood in sufficient quantities to produce very serious anaemia and even death. Fortunately these cases are not frequent, and when they do occur, the baby is given a complete transfusion soon after birth so that that baby’s blood is replaced by blood containing no antibodies to the rhesus factor. It is now possible for this transfusion to be carrried out before birth. Another recently developed technique is for the mother to be given an injection shortly after the birth of her first child which prevents the Rh+ cells from stimulating the production of the harmful antibody. 72 X Class Transportation - The circulatory system Annexure-II Thalassemia Thalassemia is a group of inherited blood disorders characterized by mild to severe anaemia caused by haemoglobin deficiency in the red blood cells. In individuals with thalassemia, the production of the oxygen carrying blood pigment haemoglobin is abnormally low. There are two main types of thalassemia: alpha thalassemia and beta thalassemia. In each variant a different part of the haemoglobin protein is defective. Individuals with mild thalassemia may have symptoms, such as anaemia, enlarged liver and spleen, increased susceptibility to infections, slow growth, thin and brittle bones, and heart failure. 4.5% of world population (250 million) suffering with thalassemia minor. Facts about Thalassemia • Thalassemia is a serious Inherited Blood Disorder. • • There are over 35 million Indians are

carriers of the abnormal Gene for Thalassemia. It is estimated that about 1,00,000 infants are born with major Haemoglobinopathies • every year in the world. 10,000 – 12,000 Thalassemic children are born every year in our country. • • Survival depends upon repeated blood transfusion and costly medicines. • Thalassemia can be prevented by awareness, pre marital or pre conceptual screening followed by antenatal diagnosis is required. Treatment Thalassemia major should be diagnosed as early as possible in order to prevent growth restriction, frail bones and infections in the first year of life. The infant’s haemoglobin levels and development should therefore be monitored closely. If Hb is less than 70% or the child shows signs of poor growth and development. Regular transfusion is the treatment of choice. According to the WHO, the aim of this treatment is to retain a median haemoglobin value of 115–120 grams per liter. This can usually be achieved by carrying out transfusions of concentrated red blood cells at intervals of every three to four weeks. Today thalassemia major can be cured by stem cell transplantation. A prerequisite is usually that the affected individual who has siblings with identical tissue type (HLA type) a transplantation of blood stem cells referred to as a “bone marrow transplant”, can be carried out. Free distribution by A.P. Government 73 Chapter 4 Excretion - The wastage disposing system There is no factory which can manufacture a product without generating any waste. This is true of our body which is a cellular factory too. And for other organisms as well. Wastes are generated at regular intervals from the bodies of most organisms. This raise questions like. • Where are the wastes produced? • How are they produced? • What are the substances present in them? • Does the composition vary in the same organism in different situations? Let us understand such kind of questions. Living beings need energy for their survival and to perform activities either building up of body material (anabolism) or its breakdown (catabolism), collectively called metabolic activities. Organisms use different substances for metabolic activities. Different products are generated as a result of these metabolic activities. Can you name different products generated by the following life processes? Table-1 Products Life processes Photosynthesis Respiration Digestion 74 X Class Excretion The wastage disposing system • What products would the organism be able to take up for other ac- tivities? • What products which

would cause harm to the body, if they are not removed? • What happens if harmful products are not removed from our body every day? We have already learnt that different kinds of materials are produced out of various metabolic activities. Some of these may be harmful for the organism are removed from their body or packed and stored in some other forms. These are all the wastes produced in the body of an organism. We have already discussed how organisms get rid of gaseous wastes generated during photosynthesis or respiration. Other metabolic activities generate nitrogenous wastes have to be removed along with salts, excess water and several other materials. Excretion is the term coined for all the biological process involved in separation and removal of wastes or non useful products from the body. (In latin ex means out, crenere means shift.) Now let us study how excretion takes place in human being. Excretion in Human Beings A number of reactions take place during various metabolic activities. Many useful substances and energy are produced. At the same time many other things happen such as, toxic wastes may be produced, water content may increase, ionic balance in the body may be disturbed. The waste products include carbon dioxide, water, nitrogenous compounds like ammonia, urea, uric acid, bile pigments, excess salts etc. The most poisonous of all waste products of metabolism is Ammonia. Where are these waste material produced? How does the body manage them. Is there a way to detect their presence in our body? Now let us observe the test reports of Blood and Urine of a person given in table-2 and find out the components present in both Blood and Urine. (For 24 hours urine test urine collected for 24 hours for that 100150 ml sample will be tested.) • What are the substances present in blood? • What are the substances present in urine? • What are the substances present both in blood and urine? • Which substances are present above the normal limits both in the blood and urine? • What do you think a reading about normal limits indicates? Free distribution by A.P. Government 75 Table-2: DEPARTMENT OF BIOCHEMISTRY REPORT ON PLASMA/SERUM (BLOOD) ANALYSIS TEST/METHOD RESULT UNITS RANGE GLUCOSE FASTING SODIUM POTASSIUM CHLORIDES UREA CREATININE URIC ACID TOTAL CHOLESTEROL TRIGLYCERIDES CALCIUM PHOS

PHORUS BILURUBIN(TOTAL) TOTAL PROTEINS ALBUMIN 82 137 4.10 101 29 2.8. 7.50 221 167 9.40 4.50 0.70 7.20 4.60 mg/dl mmoles/L mmoles/L mmoles/L mg/dl mg/dl mg/dl mg/dl mg/dl mg/dl mg/dl mg/dl g/dl g/dl 60-100 (GOD POD) 135-145 3.5-5.0 95-106 15-40 0.6-1.5 3.0-5.0 150-200 60-200 8.0-10.5 3-4.5 0.1-0.8 6.0-7.5 3.0-5.0 Table-3: DEPARTMENT OF BIOCHEMISTRY REPORT ON URINE ANALYSIS TEST/METHOD RESULT 24 hrs.Protein 24 hrs Creatinine 24 hrs.Calcium 24hrs.phosphorous 24hrs.uric Acid ELECTROLYTES : Sodium potassium Osmolality (calculated) Glucose Chlorides Urea 90 2.7 305 0.8 800 140 50 180 65 128 35 UNITS mg/day mg/day mg/day mg/day mg/day mmol/L mmol/L mosm/L mg/dl mmol/L gm/day RANGE <100 mg 1-2 Up to 200 upto 1g upto 600 125-250 25-100 100-600 50-80 120-130 20-30 m moles / L means millimoles per litre, mg/dl means milligram per deci litre. 76 X Class Excretion The wastage disposing system • What are the materials needed to removed from our body? • From where do these materials removed? • What are the organs that seperate excretory materials? • How do you think the body must be remove waste substances? Studying the structure and function of our excretory system will help us to understand this better. Excretory System in Human being In human beings excretion mainly occurs through a urinary or excretory system consisting of a pair of kidneys, a pair of ureters, urinary bladder and urethra, as shown in the fig-4. Now let us observe external and internal features of a kidney in

goat / sheep, which is similar to Human kidney in function. Lab Activity Aim: Studying the external and internal features of a kidney Materials required: Freshly collected specimen of sheep/goat’s kidney from the butcher or 3D Model of a kidney, sharp blade/scalpel, tray and a jug of water. Procedure for observation: Before coming to the class wash the kidney thoroughly so that, blood is completely drained from it. Put the kidney in the tray and observe it carefully. Note your observations in the observation book. With the help of sharp blade take a longitudinal section here you are advised to do this activity under the guidance of your teacher and observe the internal structure. Draw what you have observed and compare it with fig-1,2. • What is the shape of kidneys? • What is the colour of kidney? • Do you find any attachments on upper portion of kidney? • Is the Internal structures similar to fig-2 • What is the colour of the outer part in L.S of kidney? • In L.S of kidney where do you find dark colour portion? • How many tubes are coming out from kidney fissure? Don’t forget to wash your hands with antibacterial lotion after completing dissection. Now let us know the structure of human excretory system and its functions. Free distribution by A.P. Government fig-1: Kidney of goat fig-2: LS of Kidney of goat 77 Kidneys In Human being there are a pair of bean shaped, reddish brown structures in the abdominal cavity attached to dorsal body wall (fig-3) one on either side of the back bone. The right kidney is placed slightly lower than the left kidney. Think why it is so? The size of the kidney is 10 cm in length, 5-6 cm in breadth, and 4 cm in thickness. Each kidney is convex on the outer side and concave on the inner side. The position of the right kidney is lower than the left kidney due to the presence of liver above. Let us recall the last question in your lab activity. The inner side of each kidney has a fissure or hilus for the entry of a renal artery, exit of a renal vein and an ureter. Renal artery brings oxygenated blood loaded with waste products and renal vein carries deoxygenated blood. The waste products generated in various organs of the body are filtered and removed by the kidneys. posterior vena cava dorsal aorta adren

al gland renal artery left kidney renal vein left ureter opening of ureter into bladder bladder urethra external opening fig-4: Excretory system fig-3: Location of kidneys Internal structure of the kidney: Let us observe L.S of the kidney to know more about internal structure. It shows two distinct regions. Dark coloured outer zone called the cortex and pale inner zone called medulla. Each kidney is made up of approximately more than one million (1.3 to 1.8 million) microscopic and thin tubular functional units called nephrons or uriniferous tubules. 78 X Class Excretion The wastage disposing system Structure of nephron Each nephron has basically two parts. One is malpighian body and other is renal tubule. Malpighian body: It consists of a blind cup shaped broader end of nephron called Bowman’s capsule and bunch of fine blood capillaries called glomerulus. The Bowman’s capsule and glomerulus together called malpighian capsule or renal capsule. Glomerulus develops from afferent arteriole. It gives rise to an efferent arteriole. • Think why the diameter of the efferent arteriole is less than that of afferent arteriole? Because of the narrower out let (efferent arteriole) pressure exerts in the glomerulus.It functions as a filtration unit. Bowmans capsule which accommodates one glomerulus,is lined by a single layer of squamous epithelial cells called podocyte cells. There are fine pores between podocyte cells to allow passage of materials filtered out of glomerulus. cortex medulla renal artery renal vein nephron malpighian body glomerulus { ureter fig-5: Internal structure of kidney afferent arteriole efferent arteriole Bowman’s capsul first convoluted tubule second convoluted tubule collecting duct loop of Henle capillary network open to pelvis fig-6: Structure of a nephron Renal tubule: It has three parts. First or proximal convoluted tubule (PCT), loop of Henle, which is U shaped, second or distal convoluted tubule (DCT). Distal convoluted tubules open into a collecting tube. Collecting tube form pyramids and calyces which open into the pelvis. Pelvis leads into the ureter. All the parts of the renal tubule are covered

by a network of peritubular (around tube) capillaries formed from efferent arteriole. The peritubular capillaries join to form renal venule, which joins the other venules to form finally the renal vein. • Why the nephron is considered to be the structural and functional unit of the kidney? Free distribution by A.P. Government 79 Mechanisms of urine formation Formation of urine involves four stages i. Glomerular filtration, ii.Tubular reabsorption, iii. Tubular secretion, iv.Concentration of urine i) Glomerular filtration Blood flows from renal artery to glomerulus through afferent arteriole. Observe the fig-7 of glomerular filtration in nephron and try to answer the following questions. • Which arteriole has more diameter, afferent or efferent? • What are the substances that are filtered into the glomerular capsule? ii) Tubular Re-absorption Filtrate from glomerular is also called primary urine which almost equal to blood in chemical composition except the presence of blood cells. It passes into proximal convoluted tubule. Useful substances in primary urine are reabsorbed into peritubular net work. • If you drink more water will you pass more urine? • What are the substances reabsorbed into peritubular net work from proximal convoluted tubule (PCT)? iii) Tubular secretion After reabsorption in PCT region, the urine travels through the loop of Henle into DCT. Here some other wastes like extra salts ions of K+ Na+ Cl – and H+ secrets from peritubular capillaries in to DCT. It occurs mostly in the distal convoluted tubule, which is also surrounded by peritubular capillaries. This maintains a proper concentration and pH of the urine. Smaller amount of tubular secretion also takes place in the area of proximal convoluted tubule. Observe tubular secretion in fig-7. • What are the substances that secretes into DCT? Do you know? After the age of 40 years the number of functioning nephrons usually decreases by about 10% in every 10 years. iv) Concentration of urine Seventy five % of water content of nephric filtrate is reabsorbed in the region of proximal convoluted tubule. 10% of water passes out of filtrate through osmosis in

the area of loop of Henle. Further concentration of urine takes place in the area of collecting tubes in the presence of 80 X Class Excretion The wastage disposing system i) Glomerular filtration: Blood flows inside the glomerulus under the influence of pressure due to the narrowness of efferent arteriole. As a result it undergoes pressure filtration or ultra filtration. Waste molecules, nutrient molecules and water are filtered out and enter the Bowman’s capsule. PCT glomerolus DCT ii)Tubular reabsorption:The peritubular capillaries around PCT reabsorb all the useful components of primary urine such as glucose, amino acids, vitamin C, Potassium, Calcium, Sodium, Chlorides and 75% of Water. iii) Tubular secretion: It is the active secretion of waste products by blood capillaries into the urinary tubule. It ensures removal of all the waste products from blood, viz., urea, uric acid, creatinine, salt ions like K+, Na+ and H+ ions. This maintance proper consentration and pH of urine. fig-7: Mechanism of urine formation hormone called vasopressin. The hormone is secreted only when concentrated urine is to be passed out. Think why is it not secreted when a person drinks a lot of water? Absence of vasopressin hormone produces dilute urine. Hormone action maintains osmotic concentration of body fluids. Deficiency of vasopressin causes excessive, repeated, dilute urination called diabetes insipidus. • Why more urine is produced in winter? • What happens if reabsorption of water does not takes place? Now let us discuss remaining parts of excretory system. 2. Ureters There are a pair of whitish, narrow distensible and muscular tubes of 30cm length. Each ureter arises from hilus of the kidney. It moves downward and obliquely opens into the urinary bladder. Ureter carries urine from the kidney to the urinary bladder. The movement of urine in the ureter is through peristalsis. Free distribution by A.P. Government 81 3. Urinary bladder It is a median, pear shaped and distensible sac that occurs in the pelvic part of the abdomen. It stores urine brought by two ureters. The storage capacity of urinary bladder is 300 - 800ml. 4. U

rethra It is a tube that takes urine from urinary bladder to outside. The opening of urinary bladder into urethra is guarded by a ring of muscles or sphincter. Urethra is 4 cm long in females and about 20cm long in males. Its opening is separate in females but is in common with the reproductive tract in males (urino-genital duct). Micturition The urine is temporarily stored in the bladder. There are two sets of circular sphincter muscles in the bladder. When the bladder is filling up both these muscles are constricted, so the exit is closed. However as the pressure of the urine increases the walls of the bladder are stretched and this triggers off an automatic reflex action which causes the upper sphincter to relax. But the lower sphincter is under the control of brain. So urine can still be retained until this muscle is relaxed too. Control of urination is not possessed by very young children but is gradually learned. Urge for micturition occurs when urinary bladder is filled with 300 400 ml of urine. The stretched bladder stimulates nerve endings to develop the reflex. However, urine can be retained in the urinary bladder till it gets filled up to the maximum capacity of 700 - 800ml. At this time the urge becomes painful and leads to voluntary micturition. Total amount of urine excreted per day is about 1.6-1.8 litres. It’s quantity increases with larger intake of fluids like water, fruit juices and decreases with lesser intake. Think and discuss • Do cells need excretion? • Why we advised to take sufficient water? • Why do some children pass urine during sleep at night until 15 or 16 years of age? Composition of urine It is a transparent fluid produced by urinary system. Urine has amber color due to presence of urochrome.Composition of normal urine varies considerably depending on several factors for instance taking a protein 82 X Class Excretion The wastage disposing system rich diet will result in more formation of urea in the urine. This is because the proteins get de-aminated in the liver with subsequent formation urea. Even sugar can appear in a normal person after a heavy intake. If other conditions are constant, a large intake of liquids or water - rich food increases the volume of water in the blood, hence more urine is excreted. Urine contains 96% of water 2.5% of organic substances (urea, uric acid,

creatine, creatinine, water soluble vitamins, hormones, and oxalates etc) and 1.5% of inorganic solutes (sodium, chloride, phosphate, sulphate, magnesium, calcium, iodine). It is acidic in the beginning but becomes alkaline on standing due to decomposition of urea to form ammonia. • What happens if both kidneys fail completely? Complete and irreversible kidney failure is called end stage renal disease (ESRD). If kidneys stop working completely, our body is filled with extra water and waste products. This condition is called uremia. Our hands or feet may swell. You feel tired and weak because your body needs clean blood to function properly. Is there any solution to this problem? Let us know about artificial kidney. Dialysis (Artificial kidney) Kidneys are vital organs for survival. Several factors like infections, injury, very high blood pressure, very high blood sugar or restricted blood flow to kidneys. This leads to accumulation of poisonous wastes in the body and leads to death. Dialysis machine is used to filter the blood of a person when both kidneys are damaged. The process is called ‘haemodialysis’. In this process blood is taken out from the main artery, mixed with an anticoagulant, such as heparin, and then pumped into the apparatus called dialyzer. In this apparatus blood flows through channels or tubes. These tubes are embedded in the dialyzing fluid. The membrane separates the blood flowing inside the tube and dialyzing fluid (dialysis), which has the same composition as that of plasma, except the nitrogenous wastes. fig-8: Dialysis As nitrogenous wastes are absent in dialyzing fluids, these substances from the blood move out freely, there by cleaning the blood of its wastes. This process is called dialysis. This is similar to function of the kidney but is different as there is no reabsorption involved.The cleaned blood is pumped back to the body through a vein after adding anti-heparin. Each Free distribution by A.P. Government 83 dialysis session lasts for 3 to 6 hours. This method has been using for thousands of uremic / kidney failure patients all over the world. • Is there any long term solution for kidney failure patients? Do you know? The first kidney transplantation was performed between identical twins in 1954 by Dr. Charles Hufnagel was a surgeon at Washington, USA. In India first kidney transplantation was done on 1st

salts of calcium magnesium and iron are excreted by epithelial cells of colon (large intestine) for elimination along with the faeces. Small amount of nitrogenous wastes are also eliminated through saliva and tears. Excretion in other organisms Different organisms use varied strategies in excretion. Specific excretory organs are absent in unicellular organisms. These organisms remove waste products by simple diffusion from the body surface into the surrounding water. Fresh water organisms like Amoeba, Paramoecium possess osmoregulatory organelle called contractile vacuole. It collects water and waste from the body, swells up, reaches the surface and bursts to release its content to outside. The main execretion takes place through body surface (osmosis). Table-3 fig-11: Liver, intestine Name of the phylum organism Protozoa Porifera and coelenterates Platyhelminthes and Nematoda Annelids Arthropoda Mollusca Echinodermata Reptiles, Birds and Mammals Free distribution by A.P. Government Excretory system Simple diffusion from the body surface in to the surrounding water Water bathes almost all their cells Flame cells Nephridia Green glands, Malpighian tubules Meta nephridia Water vascular system Kidneys 85 Multicellular organisms possess different excretory organs for removal of waste materials from the body. Structural and functional complexity of excretory organs increases from sponges to humans. Sponges and coelenterates do not have specific excretory organs as water bathes almost all their cells. Excretory structures appear for the first time in Flatworms (Platyhelminthes) are known as flame cells. Now let us see how this vital process takes place in plants Excretion and release of substance in plants Do plants excrete like animals? We are amazed to answer such type of questions. You are aware that a variety of end products are formed during metabolism and these nitrogenous wastes are important. Plants does not have specific organs to excrete these wastes. Plants break down waste substances at much slower rate than in animals. Hence accumulation of waste is also much slower. Green plants in darkness and plants that do not possess chlorophyll produce carbon dioxide and water as respiratory waste products. Oxygen itself can be considered as a waste product generated during photosynthesis, that exits out side through stomata of leaves and lenticels of stem. • How plants manage or send out waste products from

its body? Plants can get rid of excess water by a process like transpiration and guttation. Waste products may be stored in leaves, bark, and fruits. When these dead leaves, bark, and ripe fruits fall off from the tree then waste products in them are get rid off. Waste gets stored in the fruits in the form of solid bodies called Raphides. However several compounds are synthesized by the plants for their own use especially for defense. Many plants synthesize chemicals and store them in roots, leaves, seeds, etc., for protection against herbivores. Most of the chemicals are unpleasant to taste. Hence, herbivores usually do not prefer to eat such plants. Some of the chemicals are toxic and may even kill the animal that eats them. Think and discuss • Why weeds and wild plants are not affected by insects and pests? Some of the plants secrete chemicals when injured. These chemicals seal the wound and help the plant to recover from an injury. Some of the plants release attractants for other organisms which will help the plants for pollination, seed dispersal or even in their nutrition. For example, plants 86 X Class Excretion The wastage disposing system having root nodules secrete chemicals to attract rhizobia into the surroundings of the roots and form a symbiotic relationship with the rhizobium. These compounds are called secondary metabolites. • Why plants shed their leaves and bark periodically? The biochemical substances produced in plants are of two types, primary metabolites and secondary metabolites. The materials like carbohydrates, fats and proteins are primary metabolites. The materials which do not require for normal growth and development are secondary metabolites. e.g.: Alkaloids, Tannins, Resins, Gums, and Latex etc. Though plants produce these chemical for their own use. Man found the usage of these chemicals for own benefits. They are generally coloured and fragrant. Alkaloids: These are nitrogenous by- products and poisonous. These are stored in different parts of the plants. Common alkaloids in plants and their uses are given below. Table-4 ALKOLOID PLANT PART USES Cinchona officinalis (Cinchona) Bark Antimalarial drug Quinine Nicotine Nicotiana tobacum (Tobacco) Leaves Morphine, Cocaine Papaver somniferum (Opium) Fruit Reserpine Rauwolfia serpentiana (Snake root) Root Caffeine Coffea Arabica (Coffee

machine is an artificial kidney which filters the blood to remove the metabolic wastes out side the body. • Kidney transplantation is a permanent solution to renal failure patients. • Different animals have different excretory organs e.g. amoeba-contractile vacuole, platyhelminthesflame cells, annelida-nephridia, arthropoda-malpighian tubule, reptiles, birds and mammals-kidney. • There are no special organs for excretion in plants. Plants store different waste materials in leaves, • bark, roots, seeds which fall of from the plants. Plant metabolites are two types i) primary metabolites eg: proteins carbohydrates and fats. ii) secondary metabolites eg: alkoloides, tannins, latex and resins. These are economically important to us. • Excretion is the removal of material from living beings where as secretion is movement of materials from one point to other. Improve your learning 1. What is meant by excretion?(AS1) 2. How are waste products excreted in amoeba?(AS1) 3. Name different excretory organs in human body and excretory material generated by them?(AS1) 4. Deepak said that ‘Nephrons are functional units of kidneys’ how will you support him?(AS1) 5. How plants manage the waste materials?(AS1) 6. Why do some people need to use a dialysis machine? Explain the principle involved in.(AS1) 7. What is meant by osmoregulation? How is it maintained in human body?(AS1) 8. Do you find any relationship between circulatory system and excretory system? What are they?(AS1) 9. Give reasons(AS1) A.Allways vasopressin is not secreted. B.When urine is discharged, in beginning it is acidic in nature later it become alkaline. C. Diameter of afferent arteriole is bigger than efferent arteriole. D.Urine is slightly thicker in summer than in winter? 10. Write differences(AS1) A. Functions of PCT and DCT C. Excretion and secretion B. Kidney and artificial kidney D. Primary metabolites and secondary metabolites 11. There is a pair of bean-shaped organs P in the human body towards the back, just above the waist. A waste product Q formed by the decomposition of unused

proteins in liver is brought into organ P through blood by an artery R. The numerous tiny filters S present in organ P clean the dirty blood goes into circulation through a vein T. The waste substance Q other waste salts and excess water form a yellowish liquid U which goes from organ P into a bag like structure V through two tubes W. This liquid is then thrown out of the body through a tube X.(AS1) (a) What is (i) organ P and (ii) waste substance Q. (b) Name (i) artery R and (ii) vein T (c) What are tiny filters S known as? (d) Name (i) liquid U (ii) structure V (iii) tubes W (iv) tube X. 90 X Class Excretion The wastage disposing system 12. The organ A of a person has been damaged completely due to a poisonous waste material B has started accumulation in his blood, making it dirty. In order to save this person’s life, the blood from an artery in the person’s arm is made to flow into long tubes made of substance E which are kept in coiled form in a tank containing solution F. This solution contains three materials G,H and similar proportions to those in normal blood. As the person’s blood passes through long tubes of substance E, most if the wastes present in it go into solution. The clean blood is then put back into a vein in the person for circulation.(AS1) (a) What is organ A? (b) Name the wastes substance B. (c) What are (i) E, and (ii) F? (d) What are G, H and I? (e) What is the process described above known as? 13. Imagine what happens if waste materials are not sent out of the body from time to time?(AS2) 14. To keep your kidneys healthy for long period what questions will you ask a nephrologist/ urologist?(AS2) 15. What are the gum yielding trees in your surroundings? What procedure you should follow to collect gum from trees?(AS3) 16. Collect the information about uses of different kinds alkaloids, take help of Library? (AS4) 17. Draw a neat labeled diagram of L.S of kidney?(AS5) 18. Describe the structure of renal tubule with neatly labled diagram.(AS5) 19. Draw a block diagram showing the

path way of excretory system in human being.(AS5) 20. If you want to explain the process of filtration in kidney what diagram you need to draw.(AS5) 21. List out the things that makes you amazing in excretory system of human being.(AS6) 22. You read about ‘Brain dead’ in this chapter. What discussions would you like to have why you think so?(AS6) 23. We people have very less awareness about organ donation, to motivate people write slogans about organ donation?(AS7) 24. After learning this chapter what habits you would like to change or follow for proper functioning of kidneys?(AS7) Fill in the blanks 1. Earthworm excreats it’s waste material through ______________. 2. The dark coloured outer zone of kidney is called _____________. 3. The process of control of water balance and ion concentration with in organism is called________. 4. Reabsorption of useful product takes place in ____________ part of nephron. 5. Gums and resins are the __________ products of the plants. 6. Bowman’s capsule and tubule taken together make a ___________. 7. The alkaloid used for malaria treatment is ________________. 8. The principle involved in dialysis is __________________. Free distribution by A.P. Government 91 9. Rubber is produced from ______________ of Heavea braziliensis. 10. ________________ invented dialysis mechine. Choose the correct answer 1. The excretory unit in the human excretory system is called (A) Neuron (b)nephron (c)nephridia (d)flame cell 2. The excretory organ in cockroch (a) malphigian tubules (b) raphids 3. Which of the following is the correct path taken by urine in our body? (c) ureters (d) nephridia ( ( ( (a) kidney ureters bladder urethra bladder (c) Kidney ureters bladder urethra 4. Malphigian tubes are excretory organs in (b) Kidney ureters bladder urethra (d) Kidney bladder ureters urethra (a) earth worm (b) house fly (c) flat worm (d) hen 5. Major component of urine is (a) u

rea (b) sodium (c) water (d) creatine 6. Special excretory organs are absent in (a) birds (b) amoeba (c) sponges (d) a and b 7. Which of the following hormone has direct impact on urination? (a) adrenal (b) vasopressin (c) creatine (d) estrogen 8. Amber colour to urine due to (a) urochrome ( b) bilerubine (c) bileverdine (d) chlorides 9. Sequence of urine formation in nephron is (a) Glomerular filtration, Tubular reabsorption, Tubular secretion (b) Tubular reabsorption, Tubular secretion, Glomerular filtration, (c) Tubular secretion, Glomerular filtration, Tubular reabsorption (d) Tubular reabsorption, concentration of urine, Tubular secretion 10. Part of the nephron that exists in outer zone of kidney. a) Loop of the henle b) PCT 11. After having lunch or dinner one can feel to pass urine, because of a b) solids become liquids d) spincter relaxation a) stomach pressures on bladder c) water content in food material c) DCT d) Bowman’s capsule ( ( ( ( ( ( ( ( ) ) ) ) ) ) ) ) ) ) ) 92 X Class Excretion The wastage disposing system We can live even after death Five organs of 18 year old youth donated Dc correspondent, Hyderabad, 20 June 2013 Five organs of 18 year old H.S. YASWANTH KUMAR were donated by his father H V Shiva kumar to the organ donation wing of jeevandan scheme on Thursday. Yaswanth had met an accident on June 15 while he was travelling in a shared Autorikshaw from Jagadgirigutta. He was rushed to Nizam Institute of Medical Sciences (NIMS).The Nuero surgeons at NIMS declared him brain dead. Jeevandan counsellors obtained the consent of Mr. Shiva kumar,who agreed to donate Yaswanth’s kidneys, two heart valves, liver. These organs were retrieved and sent to various Hospitals for Transplantaion. Dr. in-charge of Swarnalatha Jeevandan scheme, said in a statement. Think how great Yaswan

th’s parents are? Annexure Organ donation - A gift for life So many patients are waiting for suitable organ due to failure of vital organs. In Hyderabad where there are kidney transplantation facilities minimum 25 patients per hospital are waiting for kidney donors. Daily 10 - 100 people met with accident in our State. Out of them some people get brain dead. If we collect organs from brain dead patients in time, we can save minimum 5 peoples’ life. But lack of awareness on organ donation those who are willing to donate organs and those who need organs do not get proper information even facilities are there. Medical personnels from government and private hospitals are not informing about brain dead Patients. If they inform in appropriate time it will be very useful to patients those who are waiting for organ donation. In Hyderabad, organ Transplantation facility is available only in two government hospitals (NIMS and Osmonia) and in more than 10 corporate hospitals. Other organs like cornea transplant organs like kidney, liver, heart, lungs, pancreas, skin, bone, intestines and eye (cornea) can transplanted from brain dead patients.The process of transplantation of organs from brain dead patients to another is called cadaver transplantation. If any person is willing to donate organs or in needy get organs. They must register their names in transplantation facility hospitals. Collect information about voluntary organisation for organ donation and make a report on them. There is very less awareness among people about organ donation. Society needs much awareness in organ donation, so that we can save many lives who are in need of different organs from donars for their survival. Instead of living in their memories, let us give them a chance to live in others for one more life. Free distribution by A.P. Government 93 Chapter 5 Co ordination - The linking system Sharpening of a pencil, grasping a door knob, walking or running, driving, and a few physical actions, all involve well coordinated movements made with well balanced postures. In fact, whenever we move the three basic functions, such as movement, balance, and coordination they work together to perform purposeful motions of body parts. This is actually quite a feat, because moving is a complex process for the body. Even standing upright is a difficult challenge of balancing on just two feet with a narrow base. Yet, it is common for us not only to stand upright easily and apparently, effortlessly, but also while keeping our balance to perform many other functions. • What other functions do

you think needed in coordination and balance? All our functions are carried out by an effort of several systems working together. For example, while movement, we hardly ever use just the skeletal system or muscular system alone, several other systems also have their own roles to play. Even within the muscular system, several muscles work in a sequence or at once. • What triggers movement of the muscles? It is a kind of pathway involving the way that our organs, tissues and cells work. All of them pick up signals of change from their surroundings and respond to them. This process triggers different functions in our body as well as by our body. For example, it is natural to move to a side of the road when we hear or see a car approaching. 94 X Class Coordination - The liking system Responding to stimuli • What helps us to respond to such signals? • Why does the living body respond to such signals? We can think of a response as an effect of a change in the environment of the organism or signals of change or ‘stimuli’.All living organisms respond to stimuli. The cat may be running because it saw a mouse. Plants grow towards the sunshine. We start sweating when it is hot and humid. The ability to react to particular stimulus in a particular situation must be of great importance in ensuring the survival of the organism. There is a sequence of events that brings about responses. They start from detecting changes in environment (both external and internal) or stimuli, transmission of the information, processing of the same. Finally the response will detect and execute the appropriate action. Let us do the following activity to find more about response to stimuli. Activity-1 Holding a falling stick Take a long scale or stick at least around ½ meter. Keep your fingers in holding position as shown in fig-1. Ask your friend to hold the stick / scale near the end and let the other end be suspended between your fingers. Let there be a very small gap around a centimeter between your thumb and stick/scale and the stick/scale and fore finger. Now let your friend allow it to fall. Try to hold it. • Could you hold it exactly at the point where it was suspended between your fingers? • Mark the point where you caught the stick. fig-1: Holding stic • How far up was this point from the end suspended between your fingers? • Why did this happen? • How fast do you think the process was? Responses are brought about by rapid changes in some muscles and such changes are usually related

erve cell 96 X Class covering also forms a partition between adjacent axons. The nerve cell body lies either in our brain or spinal cord or very close to the spinal cord in a region called dorsal or ventral root ganglion. In the brain or spinal cord, it is difficult to make out the difference between dendrites and axons on the basis of their length, often, the presence of the sheath helps us to find out but several axons here do not have the sheath. We know that the nerve cell is the structural and functional unit of nervous system. Our nervous system consists of around about 10 billion of them, which communicate with each other in a specific manner. Dendrites of one nerve cell connect to the other or to the axons of the other nerve cell through connections called as a ‘synapse’. Synapse is the functional region of contact between two neurons, where information from one neuron is transmitted or relayed to another neuron. Though these are regions of minute gaps and essentially neurons do not have any protoplasmic connection between them yet information is passed from one nerve cell to the other through these gaps either in the form of chemical or electrical signals or both. These synapses are mainly found on the brain, spinal cord and around the spinal cord. Beyond these areas the axon carries the signals to respective areas in our body. fig-4: Synapse Pathways: From stimulus to response In the holding stick activity you observed that there is coordination between eye and finger. Different pathways are taken by nerves to bring about this coordinated activity. On the basis of pathways followed, nerves are classified mainly into three different types. Afferent neurons: Afferent (or ferrying towards) which carry messages towards the central nervous system (spinal cord or brain) from nerve endings on the muscles of different sense organs that sense the change in surroundings are called stimulus detectors. These are also called ‘sensory’ nerves. fig-5: Sensory neuron Free distribution by A.P. Government 97 Efferent neuron: Efferent (or ferrying away) which carry messages from the central nervous system to parts that shall carry out the response or the effectors (nerve endings). They are also called ‘motor’ nerves. fig-6: motor neuron Association nerves: Association nerves, which link together the afferent and efferent nerves. • Which organ of your body was the detector and which the effector in Activity-1? • What do you think that the

information carried on the afferent and efferent nerves? Brain or spinal cord Afferent nerves Assossiation nerves Efferent nerves Muscles of the organ fig-7: Different nerve pathways Activity-3 Knee jerk reflex Activity-1 showed a response on which you had some control or it was voluntary (recall the use of the voluntary and involuntary muscles that you studied in class 9th.). We know that our body would also need to respond to certain situations on which we may not have a control. Such responses are called reflexes.A simple activity shall help us to understand this better. Cross the legs, in a seated position, so that the lower half of the uppermost leg hangs freely over the other. Strike the area below the knee cap sharply, while firmly grasping the front part of the thigh with the other hand. Note the changes in shape of the thigh muscles. Note that although we are fully conscious, we cannot prevent the thigh muscles from contracting. Such a response Coordination - The liking system fig-8: Knee jerk 98 X Class is said to be involuntary. Now the same thigh muscle can operate in a voluntary manner, as when we kick a football. Do you think most of the functions in our body go about in an involuntary manner? Why /Why not? Do you know? The existence of the knee jerk was first noted in 1875. At first it was doubted whether a nervous reflex was involved at all. But it was discovered that if, in an anaesthetized monkey where spinal nerves supplying the limb were cut, the knee jerk reaction would not occur. Clearly a nerve pathway was involved. During actions which are involuntary and have to be carried out in very short intervals of time, the pathway that nerves follow is a short one; it does not go up to the brain while voluntary pathways are usually longer passing through the brain. Now let us see what pathways actually are. The reflex arc Not until the end of the nineteenth century the reflex was understood in terms of pathways. Picking up information of a stimulus to generate a response involves a pathway from detectors to brain or spinal cord or a set of nerve cell heads near spinal cord to the effectors. Such a single pathway going upto the spinal cord from detectors and returning to effectors is a reflex arc. spinal cord sensory neuron motor neuron effector muscle fig-9: Reflex arc If you accidentally touch a very sharp surface with your feet, several such arcs would operate to cause the muscles of the leg to withdraw the feet. Observe the fig

-9, how our leg muscle responds when we step on a sharp edged object. • What other effectors would act under these circumstances? • What does this tell us about the association of nerves? In fact, you must have experienced, what happens when you do things consciously and otherwise. Say for example, when you are performing an action such as running upstairs. If you start to think about where your feet are going you often stumble. The interesting thing is that the same effectors Free distribution by A.P. Government 99 in the leg muscles can be made to perform very special movement under the control of the conscious mind (voluntarily). Hence in a football game, the muscles of the leg operate both by reflexes and voluntarily. Most actions of our body are actually controlled together by voluntary and involuntary pathways. Do you know? Nerve transmission from stimulus to a response can occur at a maximum speed of about 100 meters per second. • Think of any action and try to make a sketch of the reflex arc. The voluntary and involuntary actions in our body are controlled by nervous system as a whole.We may study our nervous system on the basis of areas from which nerves originate and then spread out to the whole body as mainly two divisions one is the central nervous system (CNS) and the other is peripheral nervous system (PNS) Central Nervous System (CNS) Central nervous system includes brain and spinal cord. It coordinates all neural functions. Brain cerebral hemisphere Proportionate to the body size, the human brain is the largest of all animals. The brain is present in the hard bony box like structure called cranium. It is covered by three layers called the meninges. The meninges are continuous and cover the spinal cord as well. The space between the inner layers is filled with fluid called cerebro-spinal fluid. It serves as a shock-absorbing medium and protects the brain against shocks/jerks along with the meninges and cranium. Mainly the nerve cell bodies together with capillaries form a mass called grey matter while the myelinated axons or those covered by fatty sheaths form white matter. The grey matter is usually present on the periphery while white matter is present towards the center. This is mainly due to the fact that there is a small area from where the myelinated axons leave the brain. As we fig-10: Brain brain cavity spinal cord cerebellum mid brain Coordination - The liking system pituitary gland medulla 100 X Class have already studied

, the function of the brain as a control center was known nearly 2000 years back by Greek physiologists. Brain has the following divisions – 1. Forebrain – cerebrum, diencephalon 2. Midbrain – optic lobes 3. Hindbrain – cerebellum, medulla. Table-1: Functions of the various parts of the brain Part of the brain Functions Cerebrum i) Seat of mental abilities, controls thinking, memory, reasoning, perception, emotions and speech. ii) Interprets sensations and responds to cold, heat, pain and pressure. Diencephalon i) Relay centre for sensory impulses, such as pain, temperature and light. ii) Reflex centre for muscular activities. iii) Centre for certain emotions such as anger. iv) Centre for water balance, blood pressure, body temperature, sleep and hunger. v) The hypothalamus controls the pituitary gland, which functions as the master gland. It relays motor impulses from the cerebral cortex to the spinal cord and relays sensory impulses from the spinal cord to the thalamus, reflexes for sight and hearing. i) Maintains posture, equilibrium and muscle tone. ii) Coordinates voluntary movements initiated by cerebrum. Midbrain Cerebellum Medulla oblongata i) Contains centre for cardiac, respiratory and vasomotor activities. (Vasomotor refers to actions upon a blood vessel which alter its diameter) ii) Coordinates reflexes like swallowing, coughing, sneezing and vomiting. Do you know? The brain weighs approximately 400g. Through the brain comprises little more than 2% the body’s weight, it uses 20% of the whole body energy. Free distribution by A.P. Government 101 Spinal Cord Spinal cord extends from the back of the hind brain(Medulla oblongata) to the back of the stomach or lumbar region, through the neural canal of the vertebral column. It is almost cylindrical in shape. Unlike the brain, the white matter is towards periphery while grey matter is towards the center of the spinal cord. The myelinated axons leave the spinal cord from both sides of the vertebral column. See fig-11. The role of the spinal cord in nervous control was studied largely by the experimentalists of the sixteenth and seventeenth centuries. They found that the Greeks concept of control by the brain was erroneous. Animals were shown to have the ability to respond to stimuli even when the brain was

removed. ‘Leonardo da Vinci’ (1452-1519) and ‘Stephen Hales’ (1677-1771) both recorded the survival frogs those brain had been destroyed. The animal still produced muscular moments if its skin was pinched or pricked. Both observers further recorded that the animal died as soon as spinal cord was damaged by pushing a needle down it. Such evidence suggested that the spinal cord was not simply a trunk road for instructions from the brain, but might be a control center in its own right. fig-11: Spinal cord fig-12: Leonardo da vinci • According to you what would be the function of the spinal cord? • Are all functions of our body under direct control of the brain and spinal cord? Why do you think so? Do you know? Scientists have been able to trace out the nerves that originate from brain called cranial nerves and those that originate from spinal cord called spinal nerves. There are 12 pairs of cranial nerves which arise from the brain. There are 31 pairs of spinal nerves. Peripheral nervous system Figure-13 shows you that nerves attached to the spinal cord have two types of connections or roots – One to the back or dorsal side and other to front or the ventral side of cord. The experimental work of two men, Charles 102 X Class Coordination - The liking system Bell in Scotland and Francois Magendie in France, in the early nineteenth century, showed that these roots have different functions. If the dorsal roots of an experimental animal were cut the animal made no obvious reaction. If, however, the ventral roots were even lightly touched, the muscles to which the nerve was connected switched violently. The ventral root evidently controlled muscular activity, the dorsal root did not. dorsal root dorsal horn dorsal root ganglion ventral horn ventral root spinal nerve fig-13: Periperal nerves system In 1822 they suggested that dorsal root carried messages of sensation inwards while the ventral pathway carried outwards the instruction for muscular contraction. • Which root according to you gets signals from afferent nerves? The peripheral nervous system (PNS) is a vast system of the dorsal and ventral root nerve cell heads and the network of spinal and cranial nerves that are linked to the brain and the spinal cord on one end and muscles on the other. • What do you think the end of these nerves act at the muscular end? The PNS can either involuntarily control several functions of regions like our internal organs,

blood vessels, smooth and cardiac muscles.So it is called autonomous nervous system. It has voluntary control of muscles of some areas of skin and the skeletal muscle. We can take up an example to see how certain involuntary function controlled by autonmous nervous system takes place in our body. A very evident observation is the reduction and expansion of the pupil of our eye. When we enter a dark room we cannot see anything immediately. Slowly we are able to see the things around us in the room. This is because of increase in diameter of pupil, which allows more light in. When we come out of the dark room into broad day light the diameter of the pupil decreases allowing less light to enter into the eyes. Both these functions occur under the influence of the autonomous nervous system. Several functions in our body are controlled by nerves while many of them and others are controlled by other ways as well. You might have heard about people having diabetes and know that they have to take tablets or insulin injections when the level of sugar in their blood rises.Let’s find Free distribution by A.P. Government 103 out what insulin is and how we came to know about it. This would also give us an idea of controls other than nerves in our body. Do you know? Research in the past two decades has brought out an interesting fact. Other than central nervous system and peripheral nervous system, there is a system of neurons present in our digestive tract that can function even independently of either CNS or PNS. It has been nick named as a small brain and the system is called as enteric nervous system. Coordination without nerves The Story of insulin In 1868 Paul Langerhans, Professor of Pathology at the University of Freiburg in Germany, working on the structure of the pancreas, noted certain patches of cells quite different in appearance from the normal tissue cells of the organ and richly supplied with blood vessels. They are known Islets of Langerhans (Islets stands for islands), but their function remained unknown. Many others interested in the function of pancreas and found that its removal from the body of an experimental animal would lead to the development of diseases similar to a well-known human ailment ‘sugar diabetes’. This is a condition in which the amount of free sugar in the blood and in the urine is abnormally high. It’s a cause in man was unknown but evidence pointed to the pancreas as a possible role. fig-14: Paul Langerhans

fig-15: Pancreas The next stage was reached when it was found that tying up the pancreatic duct that emerged from the duodenum( a part of the small intestine) would cause the pancreas to degenerate but the Islets of Langerhans would remain normal. Moreover, an animal so treated would not develop diabetes. This was really a strong evidence that the level of blood sugar is linked with the islet cells. By 1912, workers were convinced that the islets produced a 104 X Class Coordination - The liking system secretion which directly liberated into the blood. In Latin ‘insula’ means an island. The name insulin was coined for the secretion, even though it had not been isolated. Ten years later in Toronto, Banting, Best, and Macleod finally succeeded in extracting insulin from degenerate animal pancreases whose ducts to the intestine had been tied. When given by intravenous injection to a dog with no pancreas, this substance kept it alive and healthy with a low level of blood sugar. Insulin is now produced in large quantities for the treatment of human sufferers from sugar diabetes, to whom it is administered by injection into the skin. Insulin thus is a chemical that acts as it reaches blood from the cells that produce it. Other chemical co-ordinators The evidence that events occurring in one part of the body could be affected and indeed controlled by substances circulating in the blood was now overwhelming. In 1905 the English physiologist Starling had coined the term hormone (Greek, hormao – to impel) for such secretions. The glands secreting hormones were termed ductless glands, since they have no tube or duct to carry away their products, which pass straight into the blood. In this way they different from glands such as the liver and pancreas, whose secretions pass down ducts which are connected to other organs. The human body contains many other ductless glands (endocrine glands).Glands do not produce their hormones at a steady rate. The adrenal gland, for example, normally has a low output. What will you do if a dog is after you? What will be your first reaction? Have you ever observed any change in your body when you are afraid? Nobody wants to fight with a dog. The first thing we do is running away from the place. fig-16: Cock fight Try to note the body language of humans / animals when they are fighting / scared. If we observe our body, when we are

afraid, the rate of heart beat increases; the breath rate will be faster; blood pressure increases; the hair on the body becomes erect and we get goose bumps. The other things we might not observe are pupil dilation, skin becomes more sensitive, and rarely the bladder and the rectum may be emptied. We come to normal state only after we reach a safe spot. Free distribution by A.P. Government 105 We have already studied about nerve co-ordination, where nerves carry stimuli from sense organs to central nervous system and orders to effectors organs-the muscles. But, in the above situation the action of the nervous system is limited. All the changes in the body are carried out under the influence of a chemical called ‘Adrenalin’ hormone, released by Adrenal gland which is an endocrine gland. The various actions of the body are controlled by hormones and co-ordinated by nervous system. So in this type of conditions nervous system and endocrine system work together to bring about control and co-ordination. Ask your teacher why Adrenalin hormone is also called fight or flight hormone. The whole system of ductless glands is called the endocrine system. Information about a few of the endocrine glands is given in the accompanying table. Try to make a list of functions that you think are controlled both by the nervous and the endocrine system. Feedback mechanism Recall the fight or flight behavior of cat and dog. The amount of adrenalin hormone increases in the blood sharply in a frightening situation, getting anger or excited. • Have ever observed the duration of anger? • Why does anger come down? • What may happen if anger persists for a longer period? Anger is always short lived factor. You know that increased levels of adrenalin are responsible for anger. When the levels of adrenalin in the blood come down slowly we come to normal state. If the adrenalin levels persist for a longer period of time, regular metabolic activities are disturbed. Increase in adrenalin levels leads to anger, decrease in adrenalin levels leads to normal position. • What will happen if it is continued for longer periods of time? Similarly the sugar levels in the blood rise than normal level, they are detected by the cells of pancreas, which respond by producing more insulin into the blood. If the sugar levels come back to normal level secretion of insulin is automatically reduced. So it is necessary that the hormones are secreted by the glands in our body in precise quantities which are required for the normal functioning 106 X Class Coordination

- The liking system Free distribution by A.P. Government 107 of the body. This means that there should be some mechanism to regulate the production and release of hormones in the body. The timing and amount of hormones released by endocrine glands is controlled by the feedback mechanism, which is inbuilt in our body. None of the systems, whether nervous or chemical are totally exclusive of each other. Autonomus nervous system You know that medulla oblongata is the region that regulates heartbeat, breathing etc. the system that helps to bring about such activities of internal organs is called autonomous nervous system. Normally such involuntary activities take place by the coordinated efforts of the medulla oblongata and autonomous nervous system. fig-17: Autonomous nervous system Now let us see how the autonomous nervous system influences the life activities. Observe the fig-17 and record your observations. • To which organs of the body do the nerves go from the ganglions near the vertebral column? 108 X Class Coordination - The liking system • What are the organs that receives nerves starting from the brain? • Which are the organs whose activities are influenced by the sympathetic system? • Which are the organs whose activities are influenced by the para sympathetic system? • What do you understand about the functions of para sympathetic system? • What you understand about the functions of sympathetic system? Ganglia near the vertebral column are connected to the spinal cord by nerves. The sympathetic system is formed by the chain of ganglia on either sides of the vertebral column and the associated nerves. The para sympathetic system is formed by the nerves arising from the ganglia of the brain and the posterior part of the spinal cord. These together constitute the autonomous nervous system. It is the part of the peripheral nervous system consisting of twelve pairs of cranial nerves and thirty one pairs of spinal nerves. Control mechanisms in plants How do plants respond to stimuli? So far we have studied how control mechanisms work in our body. Do plants also have control systems? Let us find out by doing a small activity. Activity-4 Touch the leaves of Mimosa pudica (athipathi, touch me not) plant and observe the response of leaves. Are they folding? If so in which direction? Try to give examples of situations where you may see plants responding to a certain stimulus. fig-18: Mimosa pudica Free distribution by A.P. Government 109 Do you know? Mimosa pudica leaves have pad like swellings at the base. They are called pulvini

. Here cells contain lot of water and large intercellular spaces. Due to water pressure pulvini hold the leaf erect. Touch me not plant shows nastic movement by touch. This is called thigmonasty. When we touch the leaves, an electrical impulse is generated. This impulse acts on plant hormone. Because of this hormone water in the pulvini cells which are closer to the leaf vein migrate to other side of the cells.Then pulvini loss its firmness hence leaves become fold. After 20 to 30 minutes water comes back pulvini attains firmness and leaves become erect. You might have observed the tendrils of plants growing towards a support. Can you imagine how is it happening? Would you think it is responding to a stimulus? Both plants and animals react to various stimuli around them. But the method of responding to stimuli is not similar in plants and animals. Higher animals respond to stimuli because they have a nervous system and an endocrine system. Plants do not have a well-defined nervous or endocrine system. They do have some mechanism of control by means of some chemicals or hormones. Plants can sense the presence of stimuli like light, heat, water, touch, pressure, chemicals, gravity etc. The hormones present in the plants called phytohormones (phyto means plant) control responses towards the stimuli mentioned above. Phytohormones coordinate the activities of the plant usually by controlling one or the other aspect of the growth of the plant. So plant hormones are also called growth substances. Some major plant hormones and their action are given in the following table. Table-3: Major plant hormones and their action Hormones Uses Abscisic acid closing of stomata; seed dormancy Auxins cell elongation and differentiation of shoots and roots Cytokinins promote cell division, promotion of sprouting of lateral buds, delaying the ageing in leaves, opening of stomata. Ethylene ripening of fruit Gibberellins germination of seeds and sprouting of buds; elongation of stems; stimulation of flowering; development of fruit, breaking the dormancy in seeds and buds. Discuss with your teacher about seed dormancy. 110 X Class Coordination - The liking system Activity-5 Take a glass jar and fill with soil. Sow a bean seed near the wall of the jar. This helps you to observe how root and shoot are growing. After 4 - 5 days you will notice seed germinatation. Keep the jar under the sun. Obs

erve how root and shoot grows. Then tilt the glass jar and keep the plant horizontally. Observe the direction of root and shoot growth for more than a week. • Does the shoot take a horizontal tilt after a week? • Which side of the shoot may have grown more and which side less to bring about this effect? Observe the plant growing towards light and how auxins acts on bending of stem to show a response to the sunlight. More auxin collects on the light illuminated side of the stem. So cells on that side grow faster. On opposite side cells grow slow to make the stem bend. Collect bending and straight portions of tender stem. Take transverse sections of both stems, observe them under microscope. • Do you find any difference in the shape of epidermal cells? fig-19: Bending towards sun Charles Darwin and his son Francis Darwin performed some experiments on phototropism. They covered the terminal portion of the tip of stem(coleoptile) with a cylinder of metal foil. Exposed the plant to light coming from the side. The characteristic bending of the seedling did not occur. If, light was permitted to penetrate the cylinder bending occurred normally. They stated that when seedlings are freely exposed to a lateral light some ‘influence’ is transmitted from upper to the lower part causing the material to bend. In 1926, the Dutch plant physiologist F.W. Went succeeded in separating this ‘influence’ from the plant that produced it. Went cut off coleoptile tips from oat seedlings. He placed the tips on a slice of agar and left them for about an hour. He then cut the agar into small blocks and placed a block on one side each stump of the decapitated plants. They were kept in the dark during the entire experiment. Within one hour he observed a distinct bending away from the side on which the agar block was placed. Agar block that had not been in contact with coleoptile tip produced either no bending or only a slight bending toward the side on which the block had been placed. Free distribution by A.P. Government 111 Went interpreted these experiments as showing that the coleoptile tip exerted its effect by means of chemical stimulus rather than a physical stimulus such as an electrical impulse. This chemical stimulus came to be known as auxin. In this way the first plant hormone fig-20: Went experiment auxin (greek word auxein means to increase) was discovered by Went. Trop

ic and nastic movements in plants The above experiments show that movement of individual parts of plants is possible when they are subjected to external stimuli. This type of response is called tropism or tropic movement. Sometimes the direction of stimuli determines direction of movement, sometimes the direction of movement may not be determined by direction of stimuli. This type of response is called nastic movement. Let us observe the growth of a creeper plant near window. The shoots of creeper bend towards sunlight. Such type of response of a plant to light is called photo tropism (photo means light, tropism means movement). We know that roots always grow downwards. This means that plant respond positively for gravitational force. This is called geotropism. If we observe plant which grow near a rock or wall side. You notice that all roots are growing in one direction, away from the rock or wall where water is available in the soil. This type of response to water is called hydrotropism. A very interesting thing in plants is movement of tendrils. All plants show positive response to phototropism. But in creepers like cucumber, bitter guard, the stem is weak and thin. Hence plant cannot grow erect. Tendrils play a vital role to make the plant erect. Tendrils are thin thread like growths on the leaves or stems of climbing plant. They grow towards support and wind around them. This type of response to make contact or touch is called thigmo tropism. If you taste the carpel of a flower it is sweet. Let us recall butterflies fluttering on flowers for this nectar. Ripen stigma secretes sugary substance. This chemical substance stimulates the pollen grain which falls on the stigma. Pollen grain responds to this stimulus as pollen tubes grow to reach the ovule for fertilization. This type of response to chemicals is called chemo tropism. Unequal distribution of auxins affects the root and the stem growth. High concentration of auxin stimulates stem growth and inhibit root growth. fig-21: Tendrils 112 X Class Coordination - The liking system Key words Response, stimuli, neuron, axon, synapse, afferent or sensory nerves, efferent or motor nerves, association nerves, central nervous system, brain, spinal cord, cerebrospinal fluid, peripheral nervous system, insulin, endocrine glands, hormones, feedback mechanism, plant hormones, tropic movements, nastic movements. What we have learnt • Nervous system and endocrine system are the

two systems that control and coordinate various functions in the body. • The responses of the nervous system can be classified as reflex, voluntary and involuntary actions. • The human nervous system is studied under two divisions: The central nervous system and the peripheral nervous system. • The central nervous system consists of brain and the spinal cord while the peripheral nervous system is further divided into somatic nervous system and autonomus nervous system. • The autonomus nervous system has two parts – sympathetic and parasympathetic, which cause physical reactions opposite to each other. Synapse is a gap across where signals are transmitted from one neuron to the other. • Nerve cell is the structural and functional unit of nervous system. • • Hormones produced in one body would move to another part to achieve the desired effect. • A feedback mechanism regulates the action of the hormones. • Directional movements in plants in response to specific stimuli like light, chemicals etc. are called • tropic movements. Plant hormones are usually growth effectors or inhibitors. Some growth effectors are Auxins and Gibberellins while growth inhibitors are Abscisic acid. Improve your learning 1. Fill in the missing sections in the following flow chart.(AS1) Step on a sharp edged object Brain analyse information and send commands 2. Do you think body’s team work maintains functioning of our body? Justify your answer with an example.(AS1) 3. Give an example of coordination in your body where both hormonal and nervous controls function together.(AS1) 4. Consider that you are passing by a garbage disposal area and you immediately cover your nose. Arrange the events below in a logical order by marking them from 1 to 5 to trace the events that happen in the nervous system from detection of foul smell (stimulus generation) to covering your nose (response).(AS1) (i) At the end of the axon, electrical impulse releases chemicals Free distribution by A.P. Government 113 (ii) Stimulus received on the dendritic cells of a neuron sets off chemical reaction that creates an electrical impulse (iii) Electrical impulse transmitted through cell body and axon (iv) The chemicals cross the synapse and reach the next neuron. Similarly, the electrical impulse crosses several neurons (v) Finally, the impulse is delivered from neuron to the gland that helps in recognition of the foul smell and muscle cells that help in covering the nose 5. What is a synapse? How it is useful in transfer information?(AS1) 6. Dist

inguish between(AS1) a) Stimulus and Response c) Central nervous system and peripheral nervous system d) Receptor and effector b) Afferent and Efferent nerves 6. How does Phototropism occur in plants?(AS1) 7. Give an example and explain how plants may immediately respond to a stimulus.(AS1) 8. Suggest an experiment to show how roots grow away from light in most plants.(AS1) 9. Give an example to show how hormones can influence visible changes in your body.(AS1) 10. How does a neuron differ from an ordinary cell in structure? Write notes.(AS1) 11. Is the structure of neuron suitable for transmission of impuleses? Analyse.(AS1) 12. Man is the most intelligent animal. What could be the fact that helped us to reach such a conclutssion?(AS1) 13. The axon of nerve cell in hand is sherter than the axon of nerve cell in leg. Do you support this statement? Why?(AS1) 14. Organs respond to the external stimulus by a fraction of second. How do you feel about such controlling mechanism of human body?(AS1) 15. State whether the following actions are voluntary action, reflex action or conditioned reflex.(AS1) i) Blinking iv) Salivating when food is put in the mouth. v) We close our ears when we hear un bearble sound iii) Playing on the key board ii) Cleaning the table 16. What will happen to the potted plant kept near window in the room?(AS2) 17. What happens if all functions of the human body is controlled only by brain?(AS2) 18. If you visit a doctor what doubts you would like to clarify about pancreas?(AS2) 19. Take a small potted plant. Cover base portion of the plant tightly and hang the part upside down. Observe the plant for a week. Based on your observation how can you support phototropism.(AS3) 20. Take a cock feather touch smoothly at different parts of your body. Findout which portion of the body has high sensation. Is this similar during sleeping?(AS3) 21. What procedure you follow to understand the effect of plant growth hormones (in agar medium) in the terminal portion of the tip of stem (coleoptile)?(AS3) 22. Collect information on the actions controlled by spinal cord by using reference

books from your school library.(AS4) 23. Read the following sentences and compare with endocrine glands.(AS4) Pheromones are chemical substances secreted by organisms. These act as chemical signals secreted by exocrine glands. Pheromones are used as signals by the members of same species. Honey bee secretes pheromones that attract other bees to the location of food. 24. Collect the information about cranial nerves. Spinal nerves from internet or from your school library.(AS4) 114 X Class Coordination - The liking system 25. Draw a picture representing connection between axon-axon, axon-dendrite. Why do they connect like that?(AS5) 26. Draw a neatly labelled diagram of Brain and write few points how it is protected.(AS5) 27. You are walking in the traffic suddenlyyou heard a loud sound. How coordination takes place in this situation among respected organs? Draw a block diagram to explain this situation.(AS5) 28. Make a model of neuron using suitable materials.(AS5) 29. Draw a labelled diagram of brain.(AS5) 30. Observe different actions performed by your classmate for a period of 45 minutes. Out of those action which are controled by voluntary and involuntary pathways.(AS5) 31. Its very interesting to watch a creeper entwining its tendril to the support. Is not it? How do you express your feelings in this situation?(AS6) 32. Hormones are released at a speicific place, specific time for a specific function. Prepare a cartoon on hormones with a nice caption.(AS7) Fill in the blanks 1. The largest region of the brain is ___________ 2. A point of contact between two neurons is ____________ 3. _________ phytohormon is resposible for cell elongation and differentiation of shoots and roots. 4. Thryoxin is resposible for ______________ 5. Gibberellins and auxins promote growth in plants while abscisic acid arrests the same. Some situations are discussed here, State which hormones would be needed and why? a) A gardener wants large dahlias he should use along with nutrients and other things ____________ hormone. b) In a dwarf plant the branches have to be thickened one would use ___________ hormone. c) Seeds are to be stored for a long time _____________ hormone can help. d) Cutting

curd in both the bowls. • Does it take the same time to form curd in both the bowls? • What is the time taken to form nearly 30 times the size of the bacterial colony indicate? Think, how fast they are growing. During rainy season you may have wondered how swarms of insects suddenly appear. Most insects have life cycles spanning a few days to a few months. You may find great variations in period of reproduction in yeasts, bacteria, rat, cow, elephant and man. Asexual mode of reproduction Let us study modes of reproduction involving a single parent, without involving gametes. These are known as asexual modes of reproduction. Organisms can reproduce asexually in many ways. Some of them are given here. Fission Single celled organisms, such as Paramoecium and bacteria, reproduce by splitting into two or more offsprings. This usually occurs in a symmetrical manner. They split into two by binary fission. When more cell are formed it is called multiple fission. This is often the only mode of reproduction in these organisms. • How do you think bacteria were dividing to form curd? Budding A growth on the body as a bud that grows to form nearly identical copy of parent. When the bud totally grows then it separates from the parent and survives independently. Ex: Yeast. fig-1: Fission in paramoecium Fragmentation fig-2: Budding in yeast Some can grow from a separate piece of parent organism. This can be from any part of the body. This happens only in the simplest, such as some flatworms, moulds, lichens, Spirogyra etc. grow in this manner. These may also reproduce sexually. Fragmentation is a common mode of reproduction in algae, fungi and many land plants. Free distribution by A.P. Government fig-3: Fragmentation 117 Parthenogenesis Now a days we are able to develop seedless fruits like watermelon, grapes etc. This is a process of reproduction where there is a shift from sexual to asexual mode of reproduction. • How do you think this happens? This process also occurs in nature. An organism which reproduce sexually sometimes asexually. We have utilised this process of reproduction in growing organisms of our choice with more desirable characters. In this process generally the female gametes develops into zygote without fertilization. • Would it involve two parents? fig-4: Seedless fruit This strange kind of reproduction occur in bees, ants

Ex: Nerium. Grafting: Two plants are joined together in such a way that two stems join and grow as a single plant. One which is attached to soil is called stock and the cut stem of another plant without roots is called scion. Both stock and scion are tied with help of a twine thread and covered by a polythene cover. Grafting is used to obtain a plant with desirable characters. This techqnique is very useful in propagating improved varieties of various flower and fruits (ex: Mango, citrus, apple, rose). Free distribution by A.P. Government fig-8: Cutting fig-9: Layering fig-10: Grafting 119 If you have two varieties of fruit yielding trees in your garden. One tree has the character of giving big sized fruits but less in number. The taste of the fruit is pretty good. The other one produce more number of fruits but they are neither big in size nor tasty. • What are the characters that would like to select? • What mode of propagation would help you to produce the plants with selected characters? • Whether they reproduce by budding or fission or fragmentation, organisms formed are copies of their parents. Is it true? Why? Do you know? The cutting, layering and grafting are the traditional methods for the artificial propagation of plants. Examples of plants produced in this manner are Banana, Pineapple, Orange, Grape, Rose, etc. For commercial purposes; they are being replaced by the modern technology of artificial propagation of plants involving tissue culture. In tissue culture, few plant cells or plant tissue are placed in a growth medium with plant hormones in it and it grows into new plants.Thousands of plants can be grown in very short interval of time. By grafting a very young scion (shoot part of a plant) can be made to flower and produce fruits quite fast. Collect information from your school library or internet about advantages and disadvantages of artificial vegetative propagation and discuss in your class room. Spore formation: Generally we may notice whitish threads and blackish powdery like substance on rotten fruits, bread slices and other food materials. When you touch it, the blackish powder sticks on your fingers. These are the reproductive spores produced by a fungi. Ex: Rhizopus. You have already learnt about this in the chapter ‘The story of micro organisms’ in class VIII. Rhizopus produces hundreds of microscopic reproductive units called spores. When the spore case (also called spor

angium) bursts, the spores spreads into air. These air-borne spores land on food or soil, under favourable conditions like damp and warm conditions, they germinate and produce new individuals. Most of the fungi like Rhizopus, Mucor etc., Bacteria and non-flowering plants such as ferns and mosses reproduce by the method of spore formation. 120 X Class Reproduction - The generating system Lab Activity To examine Rhizopus or common mould under the microscope, it is best to grow your own in a controlled environment. Use a soft bread that is preservative free or a roti, fruits or vegetables such as potatoes or oranges. A good sample of mould may require 4-10 days to form spores so be sure to plan ahead for this project. (Please note: this should not be done by those with allergies to mould or with severe asthma.) Rhizopus growing on bread Rhizopus under microscope Rhizopus sporongium fig-11 Leave the bread in the open air for about an hour, so it is exposed to contaminants in the air. Place the bread in a plastic bag, sprinkle water over it to have dampness then seal the bag, leaving some air inside. Place the bag in a dark, warm place. A kitchen cup board close to the stove may be one option. Or you could place it next to a window, with a bowl or plate covering it from the light. Mould will grow best in a moist environment. Mould would start growing in 2-3 days, but will take a week or more to form spores depending upon the weather. Check the piece of bread every few days, and add some water if it is drying. Avoid opening the plastic bag as much as you can. If you touch the bread, be sure to thoroughly wash your hands afterwards. When sufficient mould has formed, you can prepare a slide and examine it under the microscope. You would find whitish thread like growth with masses of black, grey and green fine dotted structures (See fig-11). The black dotted structure is that of bread mould. Take a part of the bread or roti to school in a matchbox and ask your teacher to help you to make a slide and observe under the microscope. Material required: Mould sample, plain glass slide, coverslip, water, disposable gloves. Procedure: 1. Place a drop of water in the centre of the slide. Free distribution by A.P. Government 121 2. Using a toothpick, scrape very

little of the mould and place it on the drop of water. 3. Take the cover slip and set it at an angle to the slide so that one edge of it touches the water drop, then carefully lower it over the drop so that the cover slip covers the specimen without trapping air bubbles underneath. 4. Use the corner of a tissue paper or blotting paper to blot up any excess water at the edges of the cover slip. 5. View the slide with a compound microscope first observe under low power. The common bread mould consists of fine thread like projections called hyphae and thin knob like structures called Sporangia (sporangium in singular). Each sporangium contains hundreds of minute spores. When the sporangium bursts, the tiny spores are dispersed in air. Try to give some more examples of organisms which reproduce through spore formation. Sporophyll: Ferns also produce spores. Collect a fern leaf which is called sporophyll. Observe the leaf carefully. On the lower surface of the leaf you find clusters of dot like structures called sporangia. These contain spores. Gently rupture the sporangia with a needle and observe spores by using magnifying lens. • Do you find any similarities between rhizopus and fern spores and sporongia? • What about mushrooms, how do they grow? Discuss fig-12: Fern sporophyll in your class. Sexual reproduction As you havestudied earlier, sexual reproduction is a way of reproduction where fusion of gametes takes place, by a process called fertilisation. Fertilisation may occurs either outside the body of the mother (external fertilisation) or inside the mother’s body (internal fertilisation). As a matter of fact, the eggs of land animals are fertilised inside the body of the mother. The fertilized eggs start dividing and growing into the embryo. External fertilisation is common in aquatic animals like most of the fishes and amphibians. The female lays a vast number of eggs in water and male release some millions of sperms on them in water. As the chance of fertilisation is controlled by nature which occurs externally, hence it is inevitable to give rise to vast number of eggs and sperms (gamete). 122 X Class Reproduction - The generating system Reproduction in a placental mammal - Man While talking about mammals especially human beings special reproductive organs have developed in males and females to carry out reproduction. Let us study them in detail. Male reproductive system In human males

, the two testes are located in pocket like structure outside the body wall called the scrotum. The male reproductive cells, the sperms, are produced in very large numbers (hundreds of millions). Observe the fig-13 of male reproductive system and findout parts essential for the transport of the sperm cells. Each testes has several lobules and each lobule contain several seminiferous tubules. They are small, highly coiled tubes and 80cm in legnth. Vasefferentia collect spermotozoa from the tubules. Vasefferentia forms epididymis. Here sperms are stored temporarily and moved into vasdeference then to uretra of penis and expels out of the body. One prostate, two cowper glands which are accessory glands in male reproducting system secretes a fluied called semen. This provide nutrients for sperm to keep alive and helps as a medium for the movement of sperms. The sperm cell is a flagellated structure with long tail. This helps them scrotum seminal ducts seminal vesicle prostate gland penis urethra epididymis testis fig-13: Male reproductory system to move towards the ovum. The development of the male reproductive organs is regulated by the male sex harmone called testosterone. You know that secondary sexual characters are also controlled by the male sex hormones, which are secreted by the testes. The production of sperms by the testes will begin when these events occur. Men produce sperm, from the age of about 13 or 14 years, and can go on doing so most of their lives, although their power to do so decreases as they grow older. Do you know? Some bacteria and other micro organisms have been found that are capable of changing the sex of the organism in which they grow. A species of wasp has lost its sexual ability to reproduce and has reverted to asexual mode. Free distribution by A.P. Government 123 Female reproductive system The two ovaries, where ova are formed, are located deep in the abdomen of female’s body. Observe the fig-14 of female reproductive system to know how it works. fallopian tube funnel ovary uterus cervix vagina fig-14: Female reproductory system The ova develop in tiny cellular structures called follicles, which at first look like cellular bubbles in the ovary. They are called graffian follicles. As a follicle grows, it develops a

cavity filled with fluid. Each follicle contains a single ovum which is formed after the process of cell division (meiosis). When an ovum is mature, the follicle ruptures at the surface of the ovary and the tiny ovum is flushed out. This release of the egg or ovum is called ovulation. Generally the ovum enters the widened funnel of an oviduct (fallopian tube), a tube that extends from the neighbourhood of an ovary to the muscular, thick-walled uterus. Fertilization occurs as the ovum passes through the oviduct thus begins a new life, fertilization with sperm would lead to for,ation of a mass that might grow to form a baby. As the egg passes from the oviduct to the uterus, we encounter one of the most marvelous control mechanisms that man and other mammals possess. The uterus at the time of fertilization is beautifully adapted to receiving the developing embryo, providing it with food, and disposing of its wastes. A few days prior to this time, the uterus is in normal condition. Then it was small, its tissues were thin, and its supply of blood vessels was poor. Now that the fertilized egg, or zygote, is about to enter, the uterus enlarges and become much larger. Its inner wall is thick, soft, and moist with fluid; its blood supply is greatly increased. It is, so to speak, just waiting for an embryonic occupant. chorion umbilicalcord amnion placenta fig-15: Human embryo Shortly we shall return to this transformation and see how it occurs and how it is timed for the arrival of the fertilized ovum. But now let us see what the transformation does for the developing embryo. The fertilized ovum undergoes division. As it moves down the oviduct and finally attaches to the soft tissues of the uterus. Once attached, the embryo 124 X Class Reproduction - The generating system sinks into the soft inner uterine wall. Then certain cells of the embryo develop into membranous structures that help to nourish, protect, and support the developing embryo. During the development of the embryo, tiny finger like projections grow from the surface of the outer membrane called chorion into the soft tissues of the uterus. Gradually, small pools of rapidly moving blood around these finger like projections in the uterine wall. These tissues of the chorion and the adjacent part of the uterine tissue make up the placenta

. Placenta is a tissue formed by the cells from the embryo and the mother. It is formed at around 12 weeks of pregnancy and becomes an important structure for nourishment of the embryo. Under normal conditions there is no direct flow of blood from mother to the young. The blood systems of the two are separated by thin membranes made up of cells that allow an exchange mainly by diffusion, of oxygen, carbon dioxide, nutrients, and waste materials. Another embryonic membrane, the amnion, grows around the embryo itself. The cavity within the amnion becomes filled with fluid called amniotic fluid. The embryo develops in this fluid-filled cavity, which keeps it moist and protects it from minor mechanical injury. Another membrane called allantois, which originates from the digestive canal of the embryo forms the major part of a tube like structure called umbilical cord. It contains the very important blood vessels that connect the embryo with the placenta. Thus the embryo develops until it is ready to be born. From the third month of pregnancy the embryo is called foetus. Pregnancy lasts, on an average, 9 months, or 280 days. This period is called gestation period. Let us observe the chart showing monthwise developmental stages of human embryo Free distribution by A.P. Government 125 fig-16: Developmental stages of human embryo Do you know? The average length of pregnancy varies by species: it is about 63 days for the domestic cat and dog, 330 days for the horse, 280 days for the cow, and 20-22 days for the rat and mouse. Child birth As pregnancy progress, the foetus of an embryo with certain characters grows and the uterus increases in diameter. Usually, at about the ninth month after fertilization. The head of the foetus is turned down towards the opening of the uterus. At birth, the head usually comes out first. Sometimes the feet come first; this makes the delivery more difficult. We still do not know much about the mechanism of child birth and how it is triggered. Childbirth begins when the muscle layers of the uterus starts to a rhythemic contract and relax, these actions are felt as labour pains. At first, muscular activity of the uterus is just strong enough to move the baby slowly toward the vagina the outer canal of the female reproductive tract. Generally, at this stage, the sac (amnion) around the baby breaks, and its fluid contents are released. This is a good sign that labour is well on its way. Then the contractions of the

muscles become stronger and more frequent, and the baby is pushed through the vagina and into the outer world. The umbilical cord leading from the baby to the placenta, is tied off and cut by the doctor. (The small piece of cord remaining attached to the baby shrivels and falls off within a few days. The navel marks the place where it once entered the body.) After the birth of the baby, the muscular contractions of the uterus continue until they push out the tissues of the placenta, which are commonly called the “afterbirth.” During the last part of pregnancy, a watery lymph like fluid called ‘colostrum’ accumulates in the mammary glands, which have gradually been enlarging and undergoing a transformation. For the first few days after the baby is born, the mammary glands secrete only colostrum. It is very important to feed this to the new born baby. It helps in developing the immune system of the child. umbellical cord placenta amnoin cervix baby fluid fig-17: Shortly before birth 126 X Class Reproduction - The generating system Do you know? Need for sexual reproduction Asexual reproduction as we have studied produce organisms which are normally copies of the single parent. Sexual reproduction would require two parents and organism produced would have a combination of characters of both parents. Asexual reproduction appears to be more efficient as only one parent is required and no time or energy is spent in finding a mate. But sexual reproduction helps organisms to develop characters that would be help them to adapt better to their surroundings. Think of the paramoecium mentioned in the begining of the chapter. When compare with animals sexual reproduction is less complex in most flowering plants. Let us study how it happens in them. Sexual reproduction in plants So far we know about nearly 275,000 species of flowering plants. With a few exceptions, all of them give rise to seeds enclosed in fruits. Most of the plants you are familiar with are mostly flowering plants. Their characters are quite remarkable. The plant size range from trees weighing many tonns to tiny water plants about the size of a rice grain. A sal tree growing in the Himalyan moutains, a giant cactus in the Sahara desert, an orchid plant on the branch of a jungle tree-all are flowering plants. Now let us examine the essentials parts of sexual reproduction in flowering plants. Flower - The reproductive part The reproductive parts of flowering plants are located in the flower. You

have already studied the different parts of the flower- sepals, petals, stamens and carpels. The reproductive parts of the flower which possess the sex cells or germ cells called stamens and carpels. • What function do you think is served by petals and sepals? • Draw the diagram of the flower that you collect and label the parts shown and write their functions. Flowers having either stamens or carpels are called unisexual like that of fig-18: Structure of flower Free distribution by A.P. Government 127 bottle gourd and papaya. Flowers having both the stamen and carpel are bisexual like Datura. Stamens (male portion called androecium) produce male sex cells in the pollen grain. Carpels (female portions called Gynoecium) produce female sex cells in ovules inside ovaries. Carpels have three main parts, one to receive the pollen called as stigma, one for passage of compatible male sex cells called the style and the part where fusion of male and female sex cells occur to form zygote, is the ovary. The plants having flowers where male reproductive cells of stamen of the flower fertilise the female reproductive cell of the carpel of the same flower is called self-pollination. We can see this type of pollination in plants like those of the pea family. Try to find out some other plants that are self-pollinating types. Are there any observable characters that help you to find out whether a plant is self-pollinating type or not? The illustrations given here will help you. If anthers are present below the stigma of the carpel. • How does the male reproductive cells fertilise the female reproductive cells in flowers of such plants? You have studied in earlier classes how birds and insects help plants as agents of pollination. What happens in plants that carry the female reproductive structure or the male reproductive structure borne in separate flowers? Remember the flowers of bottle gourd you studied in earlier classes. Do you know? Darwin in1876 showed that plants when isolated had the greatest tendency to self-fertilize while when surrounded by varieties of the same flower, they readily cross fertilize. In cases where male cells of flower of a plant fertilise the other female flower on the same or different plant of the same group, this type of pollination is called cross pollination. Observe fig-21 showing plant carpel with pollen on stigma and pollen tube running down

. Do you know what is self-pollination? Let us now observe some smaller parts that are involved in the process of reproduction in plants. The male reproductive part or the stamen consists of some sac like structures at its head bearing small ball like structures. We can easily observe these structures called pollen with the help of hand lens. The pollen grain reach the female reproductive part and fertilize the egg to form a zygote. 128 X Class Reproduction - The generating system Activity-2 Observation of pollen grain Take a slide and put a few drops of water on it. Now take any flower like hibiscus, tridax, marrigold, etc. Tap the anther over the drop of water. You will see small dot like structures in water. These are pollen grains. Observe these first under hand lens then under a compound microscope. You may also see a permanent slide of pollen grain from your lab. Observe under microscope. Make a drawing of what you observe and compare with the given diagram. • How many cells are present in the pollen grain? pollen grain The given diagram shows two nuclei. Do you think they may have formed if we assume that pollen grain may have started as a single cell stage? The pollen grain germinates only on the stigma. What happens then? Inorder to find out the remaining process we must look into the structure of the ovule. Structure of the ovule An ovule is an egg-shaped structure attached by a stalk to the inner side of the ovary. Depending upon the species of plant involved, an ovary may have one, two, several, or even hundreds of ovules. At the center of each ovule is a microscopic embryo sac filled with food and water. The embryo sac is composed of gametophyte cells. pollen tube nucleus fig-19: Pollen grain stigma style ovary ovule gametophyte cells embryo sac fig-20: Structure of ovule The majority of flowering plants have an embryo sac consisting of seven cells and eight nuclei. Two of which are important to our discussion. One is a large central cell containing two nuclei. These are called polar nuclei. The other cell is the egg. It is located at the end of the embryo sac closest to the opening through which the pollen tube enters. Cells on the furface of the stigma secretes a sticky nutrient fluid contains sugars and other substances. This will help the pollengrain to germinate. Then it forms pollen tube. It

bears to nuclei. Soon after the tip of the pollen tube enters the embryo sac, the end of the tube ruptures and releases the two sperms into the embryo sac. One of the two sperms fuses with the egg to form a zygote. By the time the egg cell has been fertilized, the two polar nuclei combine to form a single fusion nucleus. Now the second sperm deposited in the embryo Free distribution by A.P. Government 129 sac by the pollen tube moves to the center and unites with the fusion nucleus. The zygote will develop into an embryonic plant within the ovule. Fertilization of the fusion nucleus stimulates the formation of a new tissue the endosperm. In which, food materials are stored as development of the ovule proceeds. stigma pollen tube style ovary integuments ovule gametophyte cells central cell antipodals polar nuclei synergids egg cell embryo sac fig-22: Female gametophyte fig-21: Fertilisation Union of one sperm with the egg, and the second sperm with the fusion nucleus is called double fertilization. As far as we know, double fertilization occurs only in flowering plants. After double fertilization, the ovule increases in size rapidly as a result of the formation of endosperm tissue by mitosis and the development of the new embryo. The embryo consists of one or more cotyledons an epicotyl and a hypocotyl. Both the epicotyl and hypocotyl are parts of a rod like axis attached to the cotyledons. The cotyledons digest and absorb the endosperm and make the stored food available for the growth of the epicotyl and hypocotyl. The cotyledons of some flowering plants, beans for example, digest, absorb, and store the foods from the endosperm as the ovule is maturing into a seed. As a consequence, the cotyledons become greatly enlarged because of stored food and the endosperm disappears more or less completely. Many other flowering plants (such as corn or castor bean), the endosperm tissue continues to grow as the ovule matures into a seed. After fertilisation, the zygote divides several times to form an embryo within the ovule. The ovule develops a tough coat and is generally converted into a seed. The ovary grows rapidly and ripens to form the fruit. Meanwhile the other floral parts

may shrivel and fall off. 130 X Class Reproduction - The generating system • Which floral parts is may be seen in a fruit? The seed produced after fertilisation contains the future plant or embryo that develops into a seedling under appropriate conditions. The process is called germination. Activity-3 Seed germination Soak few groundnut or bengal gram (chana) seeds overnight. Drain the excess water and cover the seeds with wet cloth. Leave them for a day. Keep sprinkling water at regular intervals so that they do not dry up. Open the seeds carefully and observe the parts, compare with figure to identify the parts. • How cotyledons are usefull for the plant? cotyledons plumule radicle Fig-23: Seed germination Observe the life cycle of plant as a whole in the following diagram. mature plant fertilization pollination zygote embryo simple fruit seed seedling germination fig-24: Life cycle of flowering plant Do you know? In sexually reproducing organisms useually single fertilization gives rise to zygote. In plants there occurs a second fertilization giving rise to a nutritive tissue that provides nutrition to the baby plant which develops from the zygote. The pollen grain has two cells. In one of its cells called a tube cell, there are two nuclei. They travel down Free distribution by A.P. Government 131 through the stigma and style to the ovary. One of the nuclei fertilizes the egg to form zygote and the other nucleus fertilizes fusion cucleus to form an endosperm which provides food to the baby plant. This is called double fertilization. Cell division and continuation of life Continuation of life starts from cells either those of the general body or the sex cells (gametes). Virchow (1821–1902) a proponent of cell theory is given the credit for the phrase Omnis cellula de cellula, or cells arise from pre-existing cells, indicates the importance of cell division in the creation of new cells. In 1852 a German scientist, Robert Remak, published his observations on cell division, based on his observations of embryos. This was one of the first attempts to understand the mechanism of cell division. He stated that binary fission of cells was the means of reproduction of animal cells. What happens during cell division could only be understood better when scientists came to know what is present inside the nucleus of the cell. fig-25: Walther

flamming In 1879 Walther Flemming (1843–1905) examined many kinds of animal and plant cells and selected those that showed division. He reported from his observations of such cells that there were string like structures in the nucleus which split longitudinally during cell division. He named such a process of division as mitosis (mitos- means fine threads) as the dividing structures resembled threads. He made a meticulous observation and made sketches and observed that there were a sequence of events in the process of division. A decade later these thread like structures were named as chromosome (coloured bodies) as repeatedly in efforts to see them scientists were trying to use dyes to stain the nucleus and found that these structures were stained most often. His most important discovery was chromosomes appear double in nature. Wilhelm Roux (1850-1924) proposed that chromosomes carried a different set of heritable elements and longitudinal splitting observed by Flemming, ensured the equal division of these elements. Combined with the rediscovery of Gregor Mendel’s 1866 paper on heritable elements in peas, these results highlighted the central role of the chromosomes in carrying heritable material (or genetic material). In cell division the cell divides into two halves with equal number of chromosomes which are similar to parent cell and are diploid in nature. But the chromosomes number always remained the same. Biologists 132 X Class Reproduction - The generating system also began to wonder about this. When cells divide, the daughter always have the same number of chromosomes as the parent cell. Let us assume that cell division is always preceded by mitosis. In case of man egg cells and sperm cells like other cells, must contain 46 chromosomes. But if this were so, then the union of egg nucleus and sperm nucleus, which takes place during fertilization would produce a total of 92 chromosomes in zygote. If it continues this would be 184, 368 and so on. But the situation is not like that. 1. 2. August Weiseman (1834-1914) a biologist hypothesised that In successive generations, individuals of the same species have the same number of chromosomes. In successive cell division the number of chromosomes always remain constant. fig-26: August weisman Do you know? August Weiseman was a scientist with poor eye sight, it was difficult for him to use a microscope to study cells. But there were other things that he could do. Advancement of science is not only possible by mere collection of data. Someone must

think, analyse and interpret the data. August Weiseman’s poor eyesight forced him to spend time thinking. Think how great he was! The scheme of mitotic division was confirmed in 1904 by Theodor Boveri (1862–1915). The chemical nature of the genetic material was determined after a series of experiments over the next fifty years, bone muscle skin Two kinds of cell division in the life of an individual. The chromosome numbers 2n and n are respectively the number of chromosomes following mitosis (2n) and half the number (n) following meiosis - the type of division predicted by Weisman. nerve gland blood other cells sperm egg fertilised egg immature reproductive cell fig-27: Cell division sperm egg Free distribution by A.P. Government 133 culminating in the determination of its structure the deoxy ribonucleic acid (DNA) in 1953 by James Watson(DNA) and Francis Crick. Scientists proved that mitosis takes place in all body cells which retains same number of chromosomes. Meiotic division takes place in sex cells where the chromosome number is halved. Observe the following flow chart. Cell division in Human beings We know that cell as the structural and functional units of life of any organism. In all organisms the cell divide and form new cells. The process of cell divisoin is same in unicellular organisms and highly evolved multicellular organisms like human being. Cell division is the process that transforms a human fertilized egg into a baby in nine months and into an adult in the next 20 years. Cell division and function in a multicellular organism is highly regulated. It occurs only when there is a need for it. Cells in some organs, such as heart and brain of an individual never divide. On the other hand bone marrow cells actively divide to produce red blood cells, which have a short life span in the body. For example, if you cut your finger and bleed, soon a blood clot forms to stop the bleeding. This brings in various chemicals to the site that stimulate skin cells to divide and heal the wound. Cell division ceases as the wound is completely healed. In contrast, cancer cells do not respond to such growth regulating factors and continual dividing at the expense of normal cells, thus ultimately killing the host. So it becomes important to understand the processes involved in cell division. The cell cycle will help us understand this better. G2 (3.5 hrs) M (1 hr) M G2 S G1 S (10.5 hrs) G

1 (10.5 hrs) fig-28: Interphaace Cell cycle The process of cell division is called ‘Mitosis’, which is completed in 40 to 60 minutes (this is the time of active division). The period between two cell divisions is called ‘Interphase’. This is actually the period when the genetic material makes its copy so that it is equally distributed to the daughter cells during mitosis. Interphase can be divided into three phases. G1 phase: This is the linking period between the completion of mitosis and 134 X Class Reproduction - The generating system the beginning of DNA replication (Gap 1 phase). The cell seize increase during this period. S phase: This is the period of DNA synthesis (Synthesis phase) leading duplication of chromosomes. G2 phase: This is the time between the end of DNA replication and the beginning of mitosis.(Gap 2 phase). Cell organells divide and prepare chromosome for mitosis. M phase: This is mitotic cell division phase. To understand the functional relationship between these phases, Potu Rao and Johnson (see annexure) conducted some experiments using the cell fusion technique. That is combining two cells in experimental conditions. With this cell fusion technique Johnson and Potu Rao revealed for the first time the structure of interphase(GI, S and G2) chromosomes that are not ordinarily visible under the microscope. They provided evidence on progression of cells through the cell cycle in sequential unidirectional and controlled way by a series of chemical signals that can diffuse freely between nucleus and cytoplasm. These experiments are considered to be a ‘mile stone’ in the cell cycle studies. Activity-4 Observe different stages of mitotic cell division Take permanent slides which shows different stages of mitotic cell division from your lab kit. Observe carefully under microscope. Draw diagrams what you observe, and compare your observations with the following chart. Division of cytoplasm is called Cytokinesis which finally brings about formation of two daughter cells. While observing cells in tissues undergoing division, it is not easy to differentiate different stages of division. Prophase Prophase Metaphase Anaphase Telophase fig-29: Mitosis Free distribution by A.P. Government 135 Stage 1. Prophase Table-1: Mitosis Description 1. Chromosomes contract, spiral and becomevisible even in light microscope and nucleoli become smaller (material to chromosomes). 2. Chromosomes split lengthwise to form chromat

ids, connected by centromeres. 3. Nuclear membrane breaks down. 4. Centrosome, containing rod-like centrioles, divide and form ends of spindle (probably animal cells only). (Note: No pairing of chromosomes as in meiosis). 2. Metaphase 1. Chromosomes move to spindle equator, centromeres attached to spindle fibres. 2. Centromeres split, separating the chromatids. 3. Anaphase 1. Spindle fibres attached to centromeres contract, pulling chromatids towards poles 4. Telophase 1. Chromatids elongate, become invisible, (replication at this stage to become chromosomes). 2. Nuclear membranes form round daughter nuclei. 3. Cell membrane pinches in to form daughter cells (animals) or new cell wall material becomes laid down across spindle equator (plants) 4. Nucleus divides into two and division of cytoplasm starts. Process of meiosis Unlike mitosis which is a continuous process for division in most cells. Meiosis occurs only during the formation of gametes in sexual reproduction. Meiosis has two phases. During the first phase of meiosis the parent cell (containing two sets of chromosomes) divides twice, though the chromosomes divide only once. The second phase of meiosis is similar to noramal mitosis, but chromosomes do not duplicate, more over the Prophase 1 Metaphse 1 fig-30: Meiosis Anaphase 1 Telophase 1 New cells 136 X Class Reproduction - The generating system chromosomes are distributed equally to each cell. Thus the four daughter cells have just half the number of chromosomes of the parent cell. These are haploid (containing only one set of chromosome). Thus this division is also called reduction division. You will learn more about this in further classes. • What differences do you find in mitosis and meiosis? Write in a tabular form. • What would happen if the gamets do not have half the chromosome number as the skin parent? • How would it affect the progeny formed by sexual reproduction? Reproductive health • Why did the government of India fixed the legal marriage age of boys (21 years) and girls (18 years)? • Do you feel that it is a social responsibility to control birth after having one or two children? • What do you understand by the term ‘Healthy Society’? • Will you encourage child marriage? Why? As we have seen,