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1 CHAPTER 9 NUTRITION AND RESPIRATION EXERCISES Q 1. Define nutrition. What are the different modes of nutrition? Ans: Nutrition is a process of intake, as well as utilization of nutrients by an organism. Organism can be classified into two groups based on their mode of obtaining food. 1. Autotrophic nutrition: In which organism synthesis organic materials from the inorganic source. E.g. green plants. 2. Heterotrophic Nutrition: In which energy is derived from the intake and digestion of the organic substances normally of plant or animal source. Heterotrophic mode of nutrition are of different types. Saprophytic nutrition: In which organisms obtain nutrients from the dead and decaying organic matter ex: fungi and bacteria. Parasitic nutrition: The organism which obtains food is called the parasite and organism from which food is absorbed is called the ‘host’. Eg: Few plants like cuscuta and some animals like plasmodium and roundworm. Holozoic nutrition: In which the complex organic matter in the form of solid food is ingested, digested and then absorbed into the cells and utilized. Eg: Amoeba, frog, human beings. Q 2. What is the mode of nutrition in fungi? Ans: Saprophytic nutrition. Q 3. Name the pigment which can absorb solar energy? Ans: Chlorophyll. Q 4. Name the two stages in photosynthesis. Ans: The two main stages in the process of photosynthesis are : one which is light dependent called light reaction and the other which is not dependent on light called dark reaction. Q 5. Name the factors which affect photosynthesis. Ans: The factors which affect photosynthesis are: a) Light: The rate of photosynthesis increases in moderate light intensity and in red light. b) Temperature: Increases in temperature initially accelerates the rate but high temperature inhibits photosynthesis. c) Water: the rate of photosynthesis decreases is water deficient conditions. Q6. Define herbivore and carnivore. Ans: Herbivores: Animals consume only plants for their nutrition Ex: rabbit, deer, grasshopper. Carnivores: Animals consume flesh of other animals ex: frog. hawk, tiger. 1 2 Q7 .How does amoeba engulfs its food? Ans: Amoeba obtains food by phagocytosis. Amoeba engulfs the food by forming pseudopodia. Two pseudopodia start growing from the opposite sides of amoeba. They completely encircle the food and their lips touch each other. The membranes of both the pseudopodia dissolve at the point of touching and the food is encaptured into the amoeba in a bag known as food vacuole. Q8. Name the parts of the digestive system of a grasshopper. Ans: The digestive system of grasshopper consists of foregut, midgut and hindgut. 1) Foregut: It consists of mouth, oesophagus, crop, salivary glands and gizzard. 2) Midgut: It consists of stomach and 6 digestive glands called hepatic caeca. 3) Hindgut: It consists of intestine, rectum which ends into anus. Q9. What are the functions of the liver and the pancreas? Ans: 1) Function of liver : Liver secretes bile juice, the bile juice contains bile pigments and the bile salts. The bile emulsifies present in the food. It facilitates digestion of fats by the enzymes. 2) Function of pancreas: Pancreas secretes pancreatic juice. The pancreatic juice contains digestive enzymes. The trypsin enzyme for digesting proteins, pancreatic amylase for break down of starch and pancreatic lipase to digest fats. Pancreas also secrete hormones, known as insulin and glucagons. Q 10. Define breathing. Ans: The process of letting in oxygen from air into the lungs and carbon dioxide out of the lungs is called breathing. Q 11. How is respiration different from breathing? Ans: Breathing: 1) It is a bio-physical process where oxygen is taken and carbon dioxide is given out. 2) It does not require enzymes. 3) No energy is released during this process. 4) It occurs at organ level. 5) It is found in higher animals only. Respiration: 1) It is a bio-chemical process where oxidation of food occurs and carbon dioxide is released. 2) It occurs in the presence of respiratory enzymes. 3) Energy is released in the form of ATP. 4) It occurs at cellular level. 5) It is found in all animals and plants. Q12. In which kind of respiration more energy is released? Ans: In aerobic respiration more energy is released than anaerobic respiration. Q 13. Which part of roots is involved in exchange of respiratory gases? Ans: In young roots or parts of roots the exchange of gases takes place through root hairs between root cells and the soil. 2 3 Older portion of the roots do not have root hairs. The gaseous exchange takes place through lenticels present in protective layer. Q14. What are a) stomata and b) lenticels? Ans:-Stomata is a pore, large numbers of which are present is the epidermis of leaves and young shoots. They help in exchange of gases. Lenticels is any of the raised pores in the stems of woody plants, that allow gas exchange between the atmosphere and the internal tissues. Q15. Give two points of difference between respiration in plants and respiration in animals. Ans: Respiration in plants: 1) Plants do not have respiratory system. 2) Direct diffusion of respiratory gas into the cells. Respiration in animals: 1) Animals have respiratory system 2) The respiratory gases are transported up to the tissue cells. Q16. Name the respiratory organs of 1) fish 2) mosquito 3) earthworm 4) dog Ans: Animal Respiratory organs: i) Fish: Gills ii) Mosquito: Trachea or air tubes iii) Earthworm: Skin iv) Dog: Lungs Q17. How does air reach every cell of an insect? Ans: In insects, exchange of gases take place through a tracheal system. There are present small openings known as spiracles in the body wall of the insects which lead into the trachea, which further branches into trachioles. The tracheoles and blindly into the cells. Oxygen is absorbed by the cells and used to oxidize the food. During expiration, CO2 is expelled out through trachioles, tracheas and finally released through spiracles. Ext.air Q18. From where do the following take in oxygen? (a) prawn b) rat? Ans: a) Prawn has gills as respiratory organs which draw in oxygen dissolved in water. b) Rat has lungs which draw in oxygen from air. Q19.State the function of epiglottis. Ans: The function of epiglottis is that at the time of swallowing food, the epiglottis closes the tracheal opening thereby preventing the food from entering the windpipe. Q20. Why do the walls of trachea not collapse when there is less air in it? Ans: The walls of trachea does not collapse when there is less air in it as it is supported by rings of cartilage. 3 4 Q21. Name the membranes covering the lungs. Ans: pleural membrane. Q22. What happens in the carbon dioxide which collects in human tissues? Ans: Carbon dioxide which collects in human tissues is carried to the alveoli of lungs for exhalation. It is then pushed out of lungs through trachea and nostrils. Q23. Why is nutrition necessary for an organism? Ans: Nutrition is necessary for an organism because it serves as energy source which is utilised in all physiological activities for growth, development and maintenance of life. Q24.Define the following terms:(i) Saprophyte (ii) Parasite (iii)Photosynthesis (iv) Thylakoids? Ans: i) Saprophytes: the organisms which obtain nutrients from the dead and decaying organic matter. Ex: fungi, bacteria. ii) Parasites: these organisms obtain prepared food from other organisms called hosts. Ex: plasmodium (malaria parasite) iii) Photosynthesis: it is the process by which chlorophyll containing green plants synthesise their own food from CO2 and H2O in presence of light. iv) Thylakoids: the sac like lamellae structures present in the granum of chloroplast are called thylakoids. Q25. How do plants obtain food? What are the two phases of photosynthesis? Ans: Plants obtain food from carbon dioxide and water in the presence of sunlight inside the chlorophyll containing cells by process called photosynthesis. The equation involved is: sunlight 6CO2 +12H2O C6 H12O6+6H2O+6O2 chlorophyll Glucose The two phases of photosynthesis are: i) Light reaction or the photochemical phase, which starts with the absorption of light by the chlorophyll molecules. ii) Dark reaction or the biosynthetic phase, where the carbon dioxide is fixed and is reduced to carbohydrates. Q26. Name the organelle in which photosynthesis occurs. Discuss the role of chlorophyll in photosynthesis. Ans:Photosynthesis takes place in chloroplasts mostly present in green leaves. 4 5 Role of chlorophyll: chlorophyll a and b are most common in plants absorb solar energy chlorophyll molecules converts- light energy into chemical energy. By utilizing the light energy chlorophyll molecules form ATP and NADPH which are used to reduce the CO2 into glucose during the dark reaction. Q27. Describe the process of nutrition in Amoeba. Ans: `the process of nutrition in amoeba are as follows: Ameoba is holozoic in nutrition and feeds on unicellular plants and animals: such as small ciliates, diatoms, bacteria or algal filaments. When the amoeba comes in contact with the food particles, it extends the pseudopodia on either side and forms a food cup. The food material along with some amount of water becomes enclosed in the food vacuole. The process of ingestion takes about 2-3 minutes and several food vacuoles may be present at a time. Q28. Write the differences between: i) Herbivore and Carnivore ii) Autotroph and heterotroph Ans: i) Herbivores animals consume only plants for their nutrition e.g. rabbit, deer, grasshopper Carnivores animals consume flesh of other animals. E.g. frog, hawk, tiger. ii) Autotrophs are the green plants that show the phenomenon of synthesis and contain chlorophyll whereas heterotrophs are organisms like non-green plants and animals that are unable to synthesis their own food. Q29. Describe the process of digestion of food in man. Ans:Digestion is the process of conversion of large, complex and insoluble organic molecules into simpler, smaller and soluble molecules. The process of digestion of food in man starts in the mouth cavity and continues upto the intestine. In the mouth, food gets mixed up with saliva secreted by salivary glands. Saliva contains an enzyme ptyalin which break polysaccharide starch and disaccharide maltose. Ptyalin Starch Maltose (Salivary amylase) The food from the mouth cavity passes into the stomach through the oesophagus. The gastric glands of the stomach secrete gastric juice, which contains hydrochloric acid, two protein digesting enzymes - pepsin and rennin, mucus and small amount of gastric lipase. Pepsin breaks down proteins into peptones in acidic medium of gastric juice. Muscles present on the wall of stomach churn and propel and food forward. The digested food moves from stomach to duodenum of the small intestine. Duodenum receives juices from liver, i.e. bile and pancreatic juice from pancreas. The pancreatic juice contains trypsin, amylase and lipase. 5 6 The proteins, fats and carbohydrates are further digested into amino acids, glycerol and fatty acids, glucose and fructose. Finally the digestion is completed in the ileum with the secretion of the intestinal juice by intestinal glands. The intestinal juice consists of amylolytic, proteolytic and lipolytic enzymes. Q30. Respiration is a vital function of the body’. Justify. Ans: respiration is a very vital process because in this process digested food present in the body cells broken down (oxidised) to release energy. This energy is utilised for carrying out all biological functions of the cells and the body of the organisms. Thus, respiration is essential for survived and maintenance of an organism. Q31.State the differences between breathing and respiration. Ans: Breathing: (i) It is a bio-physical process where oxygen is taken and carbon dioxide is given out. ii) It does not require enzymes. iii) No energy is released during this process. iv) It occurs at organ level. v) It is found in higher animals only. Respiration: i) It is a bio-chemical process where oxidation of food occurs and carbon dioxide is released. ii) It occurs in the presence of respiratory enzymes. iii) Energy is released in the form of ATP. iv) It occurs at cellular level. v) It is found in all animals and plants. Q32. Give three points of distinction between aerobic and anaerobic respiration. Ans: Anaerobic respiration: i) When oxidation of nutrients occurs without the utilisation of molecular oxygen, it is called anaerobic metabolism. ii) Less amount of energy is produced as oxidation is not complete. iii) It occurs in higher organisms. Aerobic respiration: i) When oxidation of food nutrients occurs in the presence of molecular oxygen, it is aerobic respiration. ii) More energy is produced as oxidation is complete. iii) It occurs is lower organisms. Q33. What are stomata and lenticels? What is their role in respiration? Ans: Stomata or stoma: is a pore, large numbers of which are present in the epidermis of leaves and young shoots. Each stoma is bordered by two semicircular 6 7 guard cells. Stomata function is to exchange the gas between the plant and the atmosphere. Lenticels is any of the raised pores in the stems of woody plants. The pore is formed by the cork cambium. Which at certain points produce a loose bulky form of cork that pushes through the outer tissues to create the lenticels. Lenticels function in gas exchange between the atmosphere and the internal tissues. Q34. Describe the mode of respiration in an insect with a diagram. Ans: In insects, exchange of gases take place through a tracheal system. Insects respire though the spiracles and trachea. The trachea are the fine tubes that are well distributed in whole body of the insects. The spiracles. lead to trachea, tracheal trunk and finally it branches into tracheoles. The tracheoles end blindly into the tissue cells. During inspiration the abdominal muscles relax and the air is diffused into the tissues through spiracles and trachea. It reaches directly into the tissue through the fluid of tracheoles. It oxidises the food in the tissues and carbon dioxide is produced. During expiration, when its concentration becomes high in the body, the abdominal muscles contract and the carbon dioxide is expelled out through tracheoles,Trachea and finally released through spiracles. ( Diagram as per the test book from the page no. 129) Q36. Draw the respiratory system of human beings. Ans: ( Diagram as per the test book from the page no. 130) Q37. Describe the mechanism of breathing in human beings. Ans: mechanism of breathing: breathing is a complex mechanical process involving muscular movement that alters the volume of the thoracic cavity and thereby that of lung. There are two main steps in breathing - inspiration and expiration. Inspiration. Inspiration or inhalation is the process by which air is brought into the lungs. It involves the following steps. i) The external intercostals muscles contract causing ribs to pull out and chest cavity to expand. ii) Diaphragm contracts and is a brought down a little. This also expands the chest cavity. iii) There is a contraction of the abdominal muscles. The expansion of chest cavity creates a partial vacuum and atmospheric air rushes the lung. Expiration: after the exchange of gases in the lungs, the air has to expelled. Expulsion of air from the lungs is called expiration. It involves the following steps: i) The inner intercostals muscles contract and diaphragm and the abdominal muscles relax. ii) This leads to a decrease in volume of chest cavity and increases pressure of lungs. iii) The air in the lungs is pushed out through the nose into the atmosphere. 7 8 Q38. Explain the mechanism of gaseous exchange between tissue and blood Ans. Exchange of respiratory gases, i .e. Oxygen and carbon dioxide Occurs between the blood and tissues. In tissues, oxygen is used up for their activities and carbon dioxide is released. The blood from lungs has high concentration of oxygen and low concentration of carbon dioxide. Due to this difference in concentration in oxygen and Carbon dioxide, the exchange of gases takes place between tissue and blood. CHAPTER 10 TRANSPORTATION AND EXCRETION 8 9 EXERCISES Q1.what is transpiration? Ans: The loss of water in the form of vapour from the aerial parts of the plant is known as transpiration. Q2. Name the two kinds of cells of xylem? Ans: Tracheids and Vessels. Q3. Why is transportation of materials necessary? Ans: All living organisms need to transport materials from one part of the body to another. All these materials like food, water, oxygen, carbohydrates and hormones etc,, are essential for the organisms to survive. Therefore, transportation of materials is essential. Q4. Name the various cells through which water moves upwards to reach the leaves? Ans: Epidermis of root hairs root cortex Endodermis Xylem. Q5. State the term for transfer of food from leaves to other parts of the plant? Ans:Translocation. Q6. Name system responsible for transportation of materials in human beings. Ans: Circulatory system. Q7. List the components of blood Ans;Components of blood are: (i) Plasma (ii) Blood corpuscles or blood cells. (a) Red blood corpuscles (RBCs)or Erythrocytes. (b) White blood corpuscles (WBCs)or Leucocytes. (c) Blood platelets or thrombocytes. Q8. What makes Red blood corpuscles red? Ans: Hemoglobin makes RBCs red. Q9. Why are white blood corpuscles called "soldiers" of the body? Ans: White blood corpuscles can fight with disease germs present in the body carried by blood and help to maintain a healthy body. So, they are called as "soldiers" of the body. Q10. Name the four blood groups in human beings. Ans: The four blood groups in human in beings are A, B, AB, and O. 9 10 Q11. Point out two differences between an artery and a vein? Ans: Artery Vein 1. Arteries carry blood from the 1. Veins carry blood from body heart to the body organs. organs to the heart. 2. Arteries have thick walls. 2. Veins have comparatively thin 3. There are no valves in the walls. 3. There are valves in the veins. arteries. Q12. name the largest artery in our body? Ans: Aorta. Q13. What is the meaning of the term “double circulation”? Ans: The deoxygenated blood comes to the heart through Veins. It is oxygenated in the lungs and comes back to the heart. From heart oxygenated blood is distributed to all parts of the body. Since blood flows twice through the heart, it is called “double circulation”. Q14. What is the other term for "extra cellular fluid”? Ans: Lymph. Q15. Define excretion? Ans: Excretion is the process of elimination of metabolic waste products from the body of an organism. Q16. name the parts of the body responsible for excretion in: (i) Amoeba Ans: -Contractile vacuole. (ii) Earthworm Ans: - Nephridia. Q17. What is the nephrostome? Ans: The funnel like structure at the one end of nephridum in earthworm is called nephrostome. 18. From where does waste collect into the excretory part of the amoeba? Ans: The waste material is present in the cytoplasm in amoeba. This waste along with water enters the contractile vacuole. Q19. Where are the nephridia found in an earthworm? Ans: Nephridia are found attached to the septa of the earthworm. Q20.what happens to the useful substances, which flow into nephridia along with the waste? 10 11 Ans: Useful substances like glucose,etc.are absorbed by cells lining the tubules and passed into the blood. Q21. Name the excretory unit of a kidney? Ans: Nephron. Q22.Where is urine carried through the ureters? Ans: The urine is carried through ureters into the urinary bladder. Q23. What is urethra? Ans: Urethra is the muscular tube or duct by which urine is discharged from the urinary bladder in mammals. Q24. What happens to glucose which enters the Nephron along the filtrate? Ans: The fluid part of the filtrate is diffused into the uriniferous tubule while the useful part like glucose remains there which is again carried by renal veins. Q25.State the two vital functions of the human kidney. Ans: Two vital functions of human kidney are as follows: (a).Excretion. Metabolic wastes is excreted in the form of urine. (b).Osmoregulation. Maintenance of water quantity in all the parts of the body. Q26. Name the procedure used in the working of an artificial kidney. Ans:Dialysis. Q27. what is the need of special tissues or organs for transport in plants and animals? Ans:The special type of tissues or organs are necessary to perform special type of vital functions.Such as like digestion ,respiration and excretion are carried out by the living bodies. The cells in animals require oxygen,water and food .whereas in plants,carbon dioxide, water and oxygen are required. These substances required by living organisms are to be distributed throughout the body, thus there is a need for transportation system with special tissue or organs in plants and animals.In plants, there is a system of vascular channels, the xylem and phloem, while in animals blood vascular system is present. Q28.Describe transport of the following materials in plants: (i).water (ii). Minerals 11 12 (iii) Food Ans: Transport of water and mineral in plants. Water and minerals are dissolved in it and move upto leaves from root through tracheids and vessels. Tracheids and vessels are the two kinds of elements of xylem water and minerals flow from one tracheids to another tracheid.In flowering plants both tracheids and vessels or only vessels conduct water and minerals. Q29.What do you mean by ‘translocation’ with respect to transport in plants? Ans:Translocation is the process of transport of food from leaves to other parts of the plant body through phloem.It is necessary because every part of the plant needs energy to do its functions for which it requires food. Q30.What is blood?Describe its composition. Ans:Blood has a fluid matrix called plasma, and three kinds of cells.these cells are (1)Red blood corpuscles (2)white blood corpuscles and (3)Blood platelets. Plasma is colourless and contains a lot of water and many proteins. Blood looks red because of the red coloured pigment haemoglobin present in the red blood cells. Normal mature red blood cells are circular in shape and do not contain nuclei. Haemoglobin performs a very important function of carrying oxygen from lungs to tissues and carbon dioxide from tissues to lungs. Red blood cells have a life span of about 120 days. White blood cells are lesser in number than the red blood cells. They protect the body from infections. They are capable of squeezing out of capillaries to destroy foreign matter. White blood cells also manufacture antibodies which are responsible for Immunity. Blood platelets are fragments of cells. They do not possess nuclei. They participate in the coagulation of blood . Blood cells are manufactured in the bone marrow from cells called stem cells. Q31. Write a note on mechanism of blood clotting. Ans: Clotting of blood is a complex process which requires factors. As blood flows out of a damaged blood vessel, blood platelets release Thromoboplastin. Thrombin then catalyses the conversion of fibrinogen present in plasma into fibrin. Fibrin forms a mesh into which red blood corpuscles get entangled and form a blood clot. Release Injured tissues + blood platelets Thromboplastin Prothrombin Thrombin 12 13 Fibrinogen Fibrin Q33.Hema’s blood group is A,Vivek’s blood group is O,and Shidha’s blood group is AB. Who can receive blood from whom and donate blood to whom? Ans: Shikha can receive blood from all, i.e. from Hema as well as from Vivek can donate blood to all, i.e, to Hema as well as Shikha . Hema can donate her blood to Shikha only. Q34.What are antigens and antibodies? Ans:Antigen is a protein which generate the body to produce antibodies. Antibody is a specialised plasma protein produced by certain white blood cells(lymphocytes) in response to entry into the body or a foreign substance,i.e., antigen, in order to rend it harmless. Q35. Draw the human heart and label its parts. Ans: Diagram as per the text book from the page no 137, fig.10.6. Q36. State differences between artery vein and capillary. Ans: Differences between: Artery (i) (ii) (iii) (iv) Vein Artery is thick-walled. Lumen is small. Valves absent. Blood flows from heart to different organs. (i) (ii) (iii) (iv) Capillary Vein is thin walled. Lumen is big. Valves present. Blood flows from different organs to heart. (i) (ii) (iii) (iv) Extremely thin walled. Lumen is very small. Valves absent. Blood flows from arteries to veins. Q 37. Write a note on lymphatic system in human beings stating two major functions of lymph. Ans: Lymph. Lymph is also a circulatory fluid. It circulates through a system of lymphatic capillaries called lymphatic system. Lymph is a light yellow fluid containing lymphocyte cells. Lymph flows only in one direction, which is from tissue to heart. Lymphatic system contains, lymph glands, lymph nodes with lymph vessels. Q38. Describe the mechanism of excretion in amoeba and earthworm. Ans: AMOEBA: Amoeba is unicellular. IT lives in fresh water and removes waste and excess water by simple diffusion through the contractile vacuole. 13 14 Waste produced in the cell and surplus water enters into contractile vacuole from the cytoplasm. As more and more water and waste collect, the contractile vacuole increases in size and moves close to the plasma membrane, contractile vacuole bursts and releases the contents in the surrounding water. EARTHWORM:- Nephridia, the excretory organs of earthworm, are attached to the septa. A nephridium is an assembly of long tubules lined by cilia. One end of nephridium has la funnel like structure, the nephrostome. The other end has an opening, called nephrostome. The other end has an opening, called nephridiopore, through which waste fluid is drained outside. Fluid from body cavity carrying waste enters the nephrostome. Cilia in the tubule, beast to move the fluid through the nephridium. During its passage through nephridium, useful substances like, cells lining the tubules and passed into blood reabsorb glucose, etc.. Fluid with waste moves out of nephridiopore. Q39. Draw and label the parts of the human excretory system. Ans: Diagram as per the textbook from the page no 140, fig. 10.14. Q40. What is osmoregulation? How does it take place in humans? Ans: Osmoregulation is the process of regulating the water content and the concentration of salts in the body of an animal. In human body, osmoregulation is brought about by kidneys, which performs these functions: (1). It removes waste materials. (2). It carries out reabsorption of useful materials as well as control the level of water and dissolved substances in the blood and tissue fluid, thereby maintaining a constant osmotic potential within the body. Q41. Briefly describe the mechanism of urine formation. Ans:- Mechanism of Urine formation:- Urine is formed in the kidneys. There are numerous excretory units called nephrons, and each nephron is very thin thread like structures with its one end bearing a cup-shaped structure known as Bowman’s capsule. A thin network of blood vessels known as glomerulus is present in the Bowman’s capsule, which consists of afferent and efferent arterioles. Urine is formed in town stages called filtration and reabsorption. In filtration, blood is filtered into kidney tubules to form a clear fluid containing the waste substance urea, and many useful substances like glucose and amino acids. The filtration occurs in the glomeruli. The useful substances are reabsorbed from the filtrate back into the blood leaving only urea and other substance in the kidney tubules. 14 15 Q42. Which is the major nitrogenous waste product in a human being? How is it removed from the body? Ans: Urine contains urea, uric acid and ammonium carbonate in human beings. All these products are removed from the body through kidneys in the form of urine. CHAPTER 11 CONTROL AND COORDINATION EXERCISES: Q.1.what is a neuron? 15 16 Ans.A Neuron is an elongated branched cell that is fundamental unit of the nervous system and is specialized for conduction of nerve impulse. Q.2.Name any two types of tropism? Ans:- (i) Phototropism : Movement towards the light. (ii) Geotropism : Movement towards downward. Q.3. What is a phytohoromone? Name any two phytohormones? Ans:- Phytohormones can be defined as as a chemical substance which is produced naturally in plants and are capable of translocation and regulating one are more physiological process when present in low concentration. Some phytohormones are : (i) Auxins (ii) Cytokinin (iii) Gibberellin (iv) Abscisic Acid. Q.4. Mention the receptors for light and sound in animals? Ans:- (i) Photo receptors : They receive light. (ii) phono receptors : They receive sound Q. 5. How does control and coordination take place in plants? Ans. In plants the control system is not specialized. The control and co-ordination in plants is performed by chemical substances known as plants hormones or phytohormones. Q. 6. Mention names of various phytohormones? Ans. Various phytohormones are: (i) Auxins (ii) Gibberellins (iii) Cytokinins and (v) Ethylene. (iv) Abscisic Acid Q. 7. Discuss phototropism. Ans. Phototropism: When a growing plant is illuminated by a unidirectional light, it responds by bending towards the light. Q. 8. Differentiate between tropic and nastic movements. Ans. Tropic movementsNastic movements(i) Direction of movement is in direction of the stimulus. (ii) Growth takes place. (iii) Movements are slow, phototropism, geotropism.(i) Direction of movement is not determined by direction of stimulus. (ii) Growth does not take place. (iii) Movements are fast, seismonasty. the e.g. the e.g. Q. 9. Draw the diagram of a neuron. Ans. Diagram as per the textbook from the page No. 145.(Fig. No. 11.3) Q. 10. Draw a neat diagram of the nervous system in an insect. Ans. Diagram as per the textbook from the page No. 144, (Fig. No. 11.2). Q.11. Describe the central nervous system in human beings? Ans:-The central nervous system in human beings consists of brain and spinal cord. 16 17 (a) Brain - Brain is the highest coordinating centre in the body. It is covered by meanings which is made up of three layers. It is protected by cranium. Brain is broadly divided into: (i) Forebrain - The forebrain includes cerebrum and olfactory lobes. Cerebrum is the largest part of the brain. It consists of two cerebral hemispheres. Sensory and motor receptors are present in the brain. These are various regions for reception of vision (occipital lobe), reception of sound (temporal lobe), touch, smell, temperature (parietal lobe) and muscular activities (frontal lobe). Olfactory lobes are one pair and receive olfactory nerves . (ii) Mid brain -It is the small portion of the brain that connects cerebrum with the other parts of the brain and spinal cord. (iii) Hind brain - It consists of cerebellum, Pons and medulla oblongata. Cerebellum is responsible for coordination and adjustment of movement and posture. Pons regulates respiration. Medulla oblongata regulates swallowing, coughing, sneezing and vomiting. (b) Spinal cord - Medulla oblongata extends downwards, enclosed in vertebral column to form cylindrical structure known as spinal cord. It is also covered by meninges. It is the reflex centre of the body. Q.12. What is ganglion? Ans. Ganglion is referred to a mass of nervous tissue containing many cell bodies and synapses usually enclosed in a connective tissue sheath. Q.13. Mention the function of the fore brain. Ans. Fore brain includes cerebrum and olfactory lobes. Different areas perform different function. The cerebrum has sensory areas where information is received from the sense organ called receptors. Similarly cerebrum has motor areas from where instructions are sent to the various muscles of the body called effectors to do the various jobs. There are specific reasons in cerebrum for each kind of stimulus and response ,e.g, i)occipital lobe:is the region for sight,i.e visual ii)reception temporal lobe: Is the region for hearing, i.e auditory reception . iii)frontal lobe :Is the region for speech ,facial muscular activities and higher mental activities iv)Parietal lobe:Is the region for taste,smell ,touch ,temperature and conscious association v)Olfactory lobe :In the fore brain lie below the cerebrum. They contain olfactory receptors which are the organs of smell. Q.14.Write the functions of any one part of hind brain? Ans) These are following parts of hind brain i)Cerebellum ,ii)pons iii)medulla Functions of Cerebellum. It regulates and co-ordinates movements and posture of the body. It helps in adjustment of the body balance. 17 18 Q.15. What is the autonomic nervous system? Ans:- The autonomic nervous system consists of a pair of chains of nerves and ganglia found on either side of the backbone. It controls the in involuntary actions of many internal organs like heart, blood vessels and glands. The autonomic nervous system consists of two parts - sympathetic and parasympathetic. Q.16.Define reflex action with suitable examples? Ans:- Reflex Action is defined as an unconscious, automatic and involuntary response of effectors, i.e, muscles and glands, to a stimulus, which is monitored through the spinal cord. e.g., Knee-jerk reflex, movement of diaphragm, coughing, sneezing, yawning and blinking of eyes are all reflex action. Q.17. Name the hormones secreted by thyroid, parathyroid and pancreas. Ans:- Thyroid --Thyroxine Parathyroid -Calcitonin Pancreas --Insulin and glucagon Q18.List the functions of testosterone and estrogen? Ans:- Functions of Testosterone. (iv) Regulation of male accessory sex organs. (v) Regulation of secondary sexual characters like moustache, beard and voice. Functions of Estrogen. (i) Regulation of female accessory sex organs. (ii) Regulation of secondary sexual characters like mammary gland, hair pattern and voice. (iii) Maintenance of Pregnancy. Q.19. Write names of three hormones secreted from pituitary? Ans:- (i) Trophic hormones. (2) Prolactin. (3) Oxytocin. (4) Vasopressin. (5) Growth hormone. Q.20.Nervous and hormonal system together perform the function of control and co-ordination in human beings. Justify the statement. Ans:- Both the systems control, co-ordinate the various functions in human body. Nervous system control various functions by the units called neurons. Neurons receive the information by sensory nerves and transfer them through motor actions. The hormones are the chemicals secreted by endocrine glands.The endocrines glands do not have ducts, so they are called ductless glands. Hormones also control the functions of various organs of the body. In this way it is true that the nervous 18 19 system and hormonal system in human body together perform the functions of control and coordination. Chapter -12 REPRODUCTION EXERCISES Q1. Name the various types of asexual reproduction? 19 20 Ans:Various types of the asexual reproduction are (a)Fission (b) Budding (c) Spore formation (d) regeneration and (e) Vegetative regeneration. Q2.Differentiate between Binary fission and multiple fission. Ans: Binary fission: It involves division of the organism into two equal halves.This method of reproduction occurs regularly among protozoans, eg: Ameoba, Paramoecium. Multiple fission: It involves division of the organism into more than two equal halves. Eg:plasmodium. Q3:List two advantages of vegetative propagation? Ans: Advantages of the vegetative propagation: (i)It is useful in propagating the plants which do not reproduce viable seeds or produce very few seeds. (ii) The plants produced by vegetative propagation have exactly the same characters that of the parent plant i.e.it helps in preserving the characters of the parent plant. Q4:name the male and female gametes in animals. Ans: In animals: (a)Male gamete is sperm. (b)Female gamete is egg or ovum. Q5: Define fertilisation? Ans: Fertilisation is defined as the process of fusion of a male gamete with a female gamete to form zygote during sexual reproduction. Q6:Define sexual reproduction? Ans: Sexual reproduction is a type of reproduction in which the two sexes, namely male and Female are involved. Q7: Mention any two functions of ovary? Ans: Functions of human ovary: (i) It produces ovum, the female gamete. (ii) It secretes estrogen and progesterone hormones. Q8:What is syngamy? Ans:The process of the fusion of the male gamete with the female gamete is called syngamy. Q9:Where does fertilization take place in human females? Ans:Fallopian tube. 20 21 Q10:Define menopause. Ans: The age at which the menstruation stops and a women loses her ability to bear the child is called menopause. Q11:Discuss briefly the different types of reproduction? Ans:There are two types of reproduction viz.asexual and sexual reproduction. Asexual reproduction: In this mode of reproduction the certain body cells or certain organs of the organism undergo repeated mitotic divisions and form two or more new individuals similar to the parent organism. The asexual reproduction includes fission, budding,spore formation, regeneration and vegetative propagation. Sexual reproduction: In this type of reproduction involvement of male sex and female sex is essential. It includes fusion of the male gamete (sperm) and female gamete (egg or ovum) called Fertilization. Q12: Describe asexual reproduction in amoeba. Ans:- In amoeba, asexual reproduction takes place by Binary Fission. During Binary fission, the nucleus of Amoeba divides into two daughter nuclei. The nuclear division is followed by the appearance of constriction the cell membrane which gradually deepens and divides the Amoeba into two daughter Amoeba. Q13: Explain various steps of budding in yeast. Ans:- Budding in Yeast:- Yeast asexually reproduce by budding. During budding, a small protuberance appears on the upper part of an adult yeast cell. This gradually grows in size. From the newly formed bud another bud appears at the tip. The budding in this way may continue for 3-4 times forming a chain of yeast cells. Q14: What are the various methods of vegetative propagation? Discuss any one method with example. Ans:- Various methods of vegetative propagation are: (i) Cutting (ii) Layering and (iii) Grafting Grafting:- In this method a cutting of desired plant called scion is taken and grafting over the stump of another plant called stock. The stock has well developed root system in the soil. Scion and stock are well tied up. After some time, the scion and stock get joined due to activity of 21 22 cambium. The stock supplies the water and minerals to the scion. This bears fruits of desired qualities on maturity. Example: Mango. Q15: Define the terms unisexual and bisexual giving one example of each. Ans:- Unisexual organism: In majority of animals like human beings, male and female sex organs are in different individuals, such organism which possesses only one kind of reproductive organs in its body, i.e. male or female is called an Unisexual organism. Bisexual organism: In most flowering plants and certain animals like tapeworm, earthworm, and starfish: a single individual has both male and female sex organs in its body. Such organism is called Bisexual organism. Q16: Mention the reproductive parts of a flower. Ans:- Stamen (male) and carpel (female). Q17: what is pollination? Describe cross pollination. Ans:- Pollination: The transfer of pollen grains from anther to stigma is called pollination. Cross Pollination: The transfer of pollen from the anther of one flower to the stigma of another flower of a different plant of the same species is called Cross Pollination. In this case, pollen grains of the same flower do not pollinate its stigmas. In Cross Pollination, the transfer of pollen grains may take place through some agency like wind, insect, bird or other agencies. Q18: Describe double fertilisation in plants. Ans:- During fertilisation in plants, the following events takes place : (i) One of the male gamete fuses with the female gamete present in the embryo sac. (ii) The other male gamete fuses with the two polar nuclei in the embryo sac. The first fusion product gives rise to the zygote while the second one forms the endosperm. The process of two fusions occuring in the embryo sac is called double fertilization. Q19: What are the male and female gonads in human beings? Mention their functions. 22 23 Ans:- Male gonads are testes and female gonads are ovaries in human beings. Functions of Testes: (i) Testes produce sperms, the male haploid gametes. (ii) Testes are responsible for secondary sexual characters. (iii) They produce male sex, i.e., testosterone. Functions of ovaries: (i) They produce female sex hormones, i.e., estrogen progesterone. (ii) They produce ova, the female haploid gamete. (iii) They are responsible for secondary sexual characters. and Q20: Mention secondary sexual characters in human male and female? Ans:- Secondary sexual characters in human male are moustaches, beard, facial and pubic hairs, etc.and in female are development of mammary gland, skinless hairy, feminine voice. Q21: Write names of one male and one female sex hormones? Ans: Male sex hormone is testosterone and female sex hormone is Estrogen. Q.22:Describe menstrual cycle? Ans:The periodic discharge of blood, mucus and uterine lining through the vaginal opening is called as Menstruation. It occurs every 28-30 days and lasts for 4-7 days. The ovarian follicle matures rapidly. The cell multiplies and the centre of the follicle degenerates. Around the 14th day, before the next menstrual cycle the follicle ruptures to release (discharge) the ovum. This process of release of ovum is known as ovulation. Simultaneously, the inner wall of uterus thickens, then uterine lining starts degenerating .At the end of 28th day, this unfertilised egg rejected along with the uterine lining. If fertilization takes place, then the embryo implants itself in the uterus. Q 23: Differentiate between menarche and menopause. Ans: - Menarche is the beginning of menstruation at puberty. Which also, marks the starting of reproductive life of a woman, whereas menopause is the stoppage of menstrual flow at the age of 45-50 years when a women loses her ability to bear children. Q24 what is ovulation? Ans: The process of release of the maturing ovum from the mature follicle in the ovary is called ovulation. 23 24 Q25 write whether true (T) or false (F) (i) Fertilization is the fusion of sperm and ovum. (ii) Duration of menstrual cycle in human female is 20 days (iii) Onset of menstruation is termed menopause. (iv) In human beings, male attains puberty little late than females. (T) (F) (F) (T) Q26: Fertilization is possible if copulation has taken place during the middle of the menstrual cycle. Give reason. Ans: - Reason: - In a normal woman ovulation (release of ovum) takes place in mid of the menstrual cycle i.e.14th day. Thus, egg is available during ovulatory period to sperms for fertilization. Q27: Mention the methods used for regulation of childbirth. Ans: Methods for Regulation of childbirth are: (i) Barrier Method (ii) Chemical Method (iii) Use of IUCDs (iv) Surgical method Q28: Write the full form of IUCD, AIDS, HIV, OC. Ans :- The full form of:(i) IUCD is Intrauterine Contraceptive Device. (ii) AIDS is Acquired Immunodeficiency Virus (iii) HIV is Human Immunodeficiency Virus. (iv) OC is Oral Contraceptive. Q29: Describe the surgical method of birth control. Ans: The surgical methods of birth control is the permanent method for prevention of childbirth. This can be done in males as well as females. In case of males a small portion of vas deference is removed or tied which is known as vasectomy. Similarly, in case of females as small portion of fallopian tube is removed or tied which is known as tubectomy. Q30: Define sexually transmitted disease and give two examples. Ans: The diseases, which spread from infected person to a healthy person by sexual contact, are called sexually transmitted diseases (STDs). For example Gonorrhea, syphilis,Trichomonasis, AIDS. 24 25 CHAPTER - 13 HEREDITY AND EVOLUTION EXERCISES Q.1. What is heredity? Ans:- Heredity refers to the transmission of characters or traits from the parents to their offspring. 25 26 Q.2. Name the plant on which Mendel performed his experiments? Ans:- Garden Pea (Pisum sativum.) Q.3. Define variation? Ans:-Variation refers to the differences in the characters or traits about the individuals of a species. Q.4. Define a gene? Ans:- Gene is a small segment of DNA on a chromosome occupying specific position in which is a hereditary determinant or unit of a biological function. Q.5.Write the expanded form of DNA? Ans:- DNA - Deoxyribonucleic Acid. Q.6. What are the components of chromosome? Ans:- Each chromosome is double or replicated and consists of two thread like structures called chromatids attached to each other at centromere. .Each chromatid has a number of dense areas arranged linearly which are known as chromomeres. They represent the areas of active genes. .Internally each chromosome has two spirally coiled threads called chromonemata embedded in matrix. These are DNA molecules. Q.7. What is a retrovirus? Ans:- A virus having RNA (Ribonucleic acid) as genetic (heredity) material is called Retrovirus. For example, Human immunodeficiency virus (HIV) is a retrovirus. Q.8. What is sex chromosome? Ans:- A chromosome which is associated with sex determination is called sex chromosome. Q.9. How is sex determined in human beings? Ans:- Sex is determined at the time of fertilisation and the two sexes are produced in approximately equal numbers. A human male has XY sex-chromosomes and produces two types of sperms (heterogametic). Either with X-chromosome or with Y-chromosome. A human female has XX sex-chromosomes and produce ova of one type (homogametic) all with X-chromosomes. Parents Gametes Male XY XY 26 Female XX X 27 Progeny XX Female (50%) XY Male (50%) Q.10. What do you understand by evolution? Ans:-Evolution is the sequence of gradual changes which takes place in the primitive organisms over million of years in which new species are produced. Q.11. Define homologous organs? Homologous organs are those organs which have the same basic structure and developmental origin but have different functions and appearance. Ans:- e.g., The forelimb of a frog, a bird and a man seem to be built from the same basic design of bones, but they perform different functions. Q.12. Explain Darwin’s theory of evolution? Ans:- According to Darwin’s theory of evolution: (i) There is natural variation within any population and some individuals have more favourable variations than others.. (ii) Population remains fairly constant even though all species produce a large number of off springs. (iii) This is due to ‘competition’ or struggle for existence between same and different species. (iv) The struggle for survival within population eliminates the unfit individuals and those with ‘favourable variations’ survive and pass on these variations to their progeny to continue. This is called natural selection. (v) The favourable variations are accumulated over a long time period leading to the origin of a new species. Q13. Define genetics. What is the contribution of Mendel in this branch of biology? Ans:- genetics is the branch of biology which deals with the study of heredity and variation. Contribution of Mendel : Mendel done his experiments on garden pea(pisum sativum) and discovered the scientific principles which govern patterns of inheritance i.e. the principle of inheritance. He explained the contrasting characters are controlled by units which he called Factors. Today these factors are called genes. Q14. Where are the genes located? What is the chemical nature of gene? Ans:- Genes are located on chromosomes. Chemically, genes are made of DNA(deoxy ribonucleic acid). Q15. During which stage of cell division can chromosome be seen? Write the features of prokaryotic and eukaryotic chromosome. Ans:- Chromosomes can be seen during the metaphase stage of the cell division. FEATURES OF: 27 28 PROKARYOTIC CHROMOSOME: Prokaryotes (bacteria) have a single chromosome. The chromosome is circular and made up of a DNA molecule associated with a few proteins. EUKARYOTIC CHROMOSOME: Eukaryotes contain many chromosomes. Each is made up of a DNA molecule and more number of basic proteins. The chromosomes are not circular but rod shaped. Q 16. Who provided the evidence of DNA as a genetic material? Write the names of components of DNA? Ans:- Griffith, Avery , McLeod and McCarty established that DNA is the genetic material. Components of DNA: A DNA molecule consists of two polynucleotide chains. Each nucleotide consists of (a) nitrogenous base (Adenine/guanine/Thymine or Cytosine) ,a pentose sugar(deoxyribose) and a phosphate group. Q17.What do you understand by the double helical structure of DNA? Who proposed this structure? Ans:-J.D.Watson & F.H.C.Crick proposed the double helical structure of DNA. The important features of the model are: i)DNA molecule consists of two polynucleotide strands forming a double helix. Each helical turn has a length of 3.4nm in which ten nucleotides present. ii)Each polynucleotide stand has a backbone of sugar and phosphate. The nitrogenous base is attached to the sugar. iii)The nitrogenous bases of the two stands of a double helix form a pair with the help of hydrogen bonds. Adenine pairs with Thymine ,whereas the guanine pairs with Cytosine. Such a specific pairing of the bases is called complimentary pairing. A and T are complimentary to each other and G is complimentary to C. The hydrogen bonding between the nitrogenous bases holds the two strands together as a result of which the base pairs remains stacked between the two strands. This structure can be compared with the steps of a spiral staircase. Q18.Describe the different types of chromosomes. Ans:- depending on the position of the centromere,a chromosome may have either equal arms, or one long and one short arm. Accordingly, four types of chromosomes are known : Metacentric:It is a chromosome with the centromere near the middle and the two arms are almost equal in length. Sub-metacentric:In this type of chromosome the centromere is situated closer to one end. As a result , one arm of the chromosome is long and one is slightly short. Acrocentric:It is the type of the chromosome which has the centromere near the end. In this case one arm is very long and the other one is very short. Telocentric:In this type of the chromosome, the Centromere is situated at the tip of the chromosome. Q19.How many types of nitrogenous bases are present inDNA?Name them. 28 29 Ans:-In DNA two types of nitrogenous bases are present. These are (i)PURINES which are adenine and guanine (ii)PYRIMIDINES which are Thymine and cytosine. Q.20.How do embryological studies provide evidence for evolution? Ans:- The similarities in embryonic development reinforce the idea of evolution from common ancestors. The sequence of embryonic development in different vertebrates shows striking similarities. Notochord and gill clefts appear in the embryos of all vertebrates. Q.21. Define evolution. And Describe the contribution of Lamarck? Ans:- Evolution is the sequence of gradual changes which takes place in the primitive organisms over millions of years in which new species are produced. Contribution of Lamarck: (i) Lamarck proposed a theory called “The Theory of inheritance of Acquired Characters” to explain the origin and evolution of species. (ii) The theory was explained in his book ‘Philosophic Zoologique. Q.22. What are homologous organs? How do they provide evidence in support of evolution? Ans:- Homologous organs are those organs which have the same basic structure and developmental origin but have different functions and appearance. Homologous organs support evolution: (i) The similarities of structure and origin of organs indicate that all vertebrates had common ancestors. For example, the forelimbs of humans, whale and bat show structural similarities but functional dissimilarities. Forelimbs in humans used for grasping or holding the things, in whale for swimming and in bat for flying. (ii) All the organs and systems of the vertebrates show fundamental similarities i.e. homology, which indicate towards common ancestry. Thus, homologous point that organic evolution has taken place. (iii) Q.23. Define the following terms? (i) Vestigial organs: Vestigial organs are those organs, which are rudimentary and functionless in the evolved forms but are well developed and functional in the ancestral forms. Eg: Vermiform appendix in human beings. (ii) Analogous organs : Are those organs which have different basic structure and developmental origin but have similar appearance and perform similar functions. Eg: The wings of and insect and a bird have different structures, but they perform the same function of flying. 29 30 CHAPTER - 16 ENVIRONMENT AND ENVIRONMENTAL PROBLEMS EXERCISES Q.1. Define pollution? Ans:- Pollution is defined as the undesirable change in the physical, chemical or biological characteristics of our land, air or water, which harmfully affect human lives or the lives of other species. 30 31 Q.2. Define pollutants? Ans:- The agents of substances that cause undesirable change leading to environmental pollution are called pollutants. Q.3. Write two natural sources of air pollution? Ans:-Forest fire and dust storm. Q.4. Write the harmful effect of ozone depletion? Ans:- (i) Due to depletion of ozone layer, more ultra violet (UV) radiation will reach the earth. UV radiations cause skin cancer, damage to eyes and immune system. (iii) Ozone layer depletion may lead to variation in rainfall, ecological disturbances and dwindling of global food supply. Q.5. Name two mechanical devices for controlling? Ans:- (i) Gravity or earth settle down the particles. (ii)Fabric filters also help in separating particles. Q.6. What are fabric filters? Ans:-The particulate matter present in polluted air are passed through a porous medium of woven fabrics and gets collected in the filtration bag known as fabric filters. Q.7. Define point source of water pollution? Ans:-Point sources are those sources of water pollution which are fixed at a place and have a specific location for discharging pollutants into a particular water body. These include factories, power plants, underground coal mines and oil wells situated close to the water sources. Q.8. Write three characteristics of potable water? Ans:- (i) It should be transparent, colorless and odorless. (ii) It should be free from harmful chemicals and bacteria. (iii) It should contain sufficient dissolved oxygen. Q.9. Define eutrophication? Ans:- Eutrophication is the process in which extra nutrients are added to a water body leading to tremendous growth of algal plants resulting in the reduction of dissolved oxygen. Q.10. How can you reduce the volume of waste? Ans:- The volume of the waste can be reduced by incineration (burning the wastes at high temperature). From biodegradable wastes, bio gas and manure can be prepared which costs much less than fuel and fertilizers. Q.11. Name two materials which can recycled? Ans:- Metals, papers , plastics can be recycled. 31 32 Q.12. How can you make a balance between environment and development? Ans:- To maintain a balance between environment and development: (i) It is essential to adopt sustainable development. It is also necessary to meet the needs of present generation without foreclosing the options for future generation. (ii) Human beings should live in harmony in nature. (iii) Technologies which are environmentally sound and based on maximizing recycling and efficient use of resources should be adopted. Q.13. How does development affect the environment? Ans:- development affects the natural environment for socio-economic considerations. It leads to degradation of environment. Some of human activities harm to the environment are : (i) Urbanization: Old villages, hills, beaches etc. have been converted into cities and big towns. (ii) Industrialization: To set up Industries for development agriculture land has been used. (iii) Construction of big dams and mining have also caused degradation of natural environment. Q.14.Define conservation? Ans:- conservation of environment may be defined as activities which can provide individual or commercial benefits but at the same time prevent excessive leading to environmental damage. Q.15. Write two conservation practices? Ans: Conservation practices: (i) Judicious use of fertilizers, intensive cropping, proper irrigation and drainage. (ii) Establishment of national parks and conservation forests, or (iii) Planting trees in place those removed for various purposes. Q.16. What is environmental pollution? Name three non- biodegradable pollutants that are harmful to human beings. Ans: Environmental pollution is the un desirable change in physical, chemical and biological characteristics of water and land. The three non-biodegradable pollutants, harmful to human beings are insecticides, DDT and plastics. Q.17. How does water get polluted? Ans. Water gets polluted by two types of sources. These are: (i)Point sources: These sources are located near water bodies and discharge pollutants directly into the water source. For example, factories power plants, coal mines ,oil wells etc, pour their wastes into rivers, lakes e.t.c. 32 33 (ii)Non-point sources: They are scattered and do not discharge any problems in a particular water source. These include run-off from the roads, fields, lawns, construction sites, logging areas e.t.c. Q.18. Describe the various pollutants in the atmosphere? Ans. Classification of pollutants. All pollutants can be classified into two groups-Bio degradable and non-biodegradable pollutants. (i)Biodegradable pollutants are the pollutants which are broken down into the simpler, harmless substances in nature in due course of time by the action of microorganisms like certain bacteria, e.g. Domestic waste products ,urine and faecal matter, sewage, agricultural residue, paper, wood, cloth and cattle dung. (ii)Non-bio degradable pollutants are those pollutants, which cannot be broken down into simpler, harmless substances in nature. These pollutants may be solid, liquid and gaseous form and may enter into the food chain and harm organisms, e.g., DDT, plastics, polythene bags, insecticides, pesticides, mercury, lead, arsenic, aluminium, radioactive wastes, e.t.c. Q.19. What is soil erosion? What are its causes and what are its effects? How can it be checked? Ans: Soil erosion is the removal and thinning of the fertile topsoil from a region due to climatic and physical processes, such as high rainfall and wind, Soil erosion occurs easily where the soil is not covered by vegetation. Causes of soil erosion: (i)Wind causes soil erosion by carrying away the topsoil particles. (i)rain causes soil erosion on unprotected topsoil by washing it down. (iii) Improper farming and tilling the field for long time causes soil erosion. (iv)Human beings cause soil erosion by clearing trees, plants and other vegetation. (v)Frequent flooding of river causes soil erosion by removing the topsoil of the fields near the riverbanks. Effects of soil erosion: (i)It can turn green forests into deserts and spoil the environment. (ii)It can lead to excessive scarcity of as food crops do not grow well. (iii)It can cause land slides in hilly areas. (iv)It can cause sudden floods in low lying areas causing loss of life and property. Prevention of soil erosion: (i) It can be prevented by intensive cropping. (ii)It can be prevented by providing proper drainage canals around the fields. (iii)Soil erosion in hilly areas can be prevented by practicing terrace farming. (iv)It can be prevented by planting trees and sowing grasses. (v)It can be prevented by constructing strong embankments along the riverbanks. Q.20 Explain the following terms with suitable examples: (i)Acid rain: Acid rain is that rain which contains small amount of acids in it, formed from the gases like sulphur dioxides and nitrogen oxides present in polluted air. it causes damage to living and non-living things. (ii)Ozone depletion: (a)causes of ozone depletion: 33 34 The use of chlorofluorocarbons in aerosol propellants, refrigerators and fire extinguishers. (b)Effects of ozone depletion: (1)The ultra violet rays enter through the depleted ozone of the ozone layer and affect the living organisms. (2)UV-rays cause skin cancer in human beings. (iii)Global warming or green house effect : The phenomena of trapping infrared radiations of sun and causing heating effect is called green house effect. Q.21. What are occupational disorders? Give examples? Ans: There are certain diseases which are related to one’s occupation. These are caused by the constant use of certain substances that sneak into air and then enter into our body. Examples are Silicosis, Asbestosis, Byssinosis, Pneumoconiosis. Q.22. What is eutrophication? Mention its harmful effects? Ans:- Eutrophication is the process in which extra nutrients are added to a water body leading to tremendous growth of algal plants resulting in the reduction of dissolved oxygen. Harmful effects of Eutrophication: The reduction of dissolved oxygen and poisonous industrial wastes affects the fish population and deprives us from one of our sources of food. Eutrophication also kills other animals living in fresh water. Q.23. Explain main types of sources of water pollution? Ans:- (i)Point sources: These sources are located near water bodies and discharge pollutants directly into the water source. For example, factories power plants, coal mines ,oil wells e.t.c. pour their wastes into rivers, lakes e.t.c. (ii)Non-point sources: They are scattered and do not discharge any problems in a particular water source. These include run-off from the roads, fields, lawns, construction sites, logging areas e.t.c. Q.24. Write in brief about : (i) UASB : Its full form is up flow anaerobic sludge blanket. It is a reactor in which the anaerobic bacteria degrade the biodegradable material present in wastewater. In this process foul odour of wastewater is removed and methane (CH4) is released. UASB reduces the pollution load up to 85%. (ii) Sustainable development: To maintain a balance between environment and development, it is necessary to strive for sustainable development to meet the needs of present generation without foreclosing the options for future generation without foreclosing the options for future generation. To achieve this, one has to consider different aspects of development. Conservation, sustainability and biological diversity are interrelated. If human beings have to survive, they have to live in harmony with nature. 34 35 Q.25. What are environmental laws? State the need for enforcing them? Ans:- The laws that have been enacted to conserve and protect the environment are called environmental laws. These laws have been enacted to protect the environment from pollution and to conserve the natural resources. Need for enforcing Environmental Laws: (i) To conserve natural resources including wild life and, (ii) To control pollution of air, water and soil. PREPARED BY : D. RAVI PGT, BIOLOGY JNV WARGAL, MEDAK DIST. 502279 35