Revision Question Bank Life Processes 1. Name the passage in sequence through which urine passes from kidney to the outside in human. How is urine prevented from flowing back into the ureter? The passage in sequence through which urine passes is given below Kidneyureterurinary bladder urethra to the outside. Urine is prevented from flowing back into the ureters because the terminal part of each ureter passes obliquely through the bladder wall and so become closed due to compression by the contracting bladder muscles. 2. Name two autotrophic plants which also show heterotrophic mode of nutrition. Why do they need to do so? Two autotrophic plants which also show heterotrophic mode of nutrition are Venus fly trap and Pitcher plant. 3. How would digestion of food be affected if the bile duct is completely blocked? Explain. If bile duct is blocked, bile juice will not reach small intestine and fat will not be digested. [Note Bile assists digestion of fats]. 4. Write down the function of the following in digestive process. (a) Bile (b) Bicarbonate secreted by duodenal wall (c) Pancreatic amylase (a) Bile emulsifies fats present in the food, i,e., breaks the fats molecules into smaller globules. www.pioneermathematics.com S.C.O. - 326, Sector 40 D, CHD. Phone: 9815527721, 4617721 11
(b) Bicarbonate ions secreted by duodenal wall make the medium alkaline, which is required for the action of pancreatic enzymes. (c) Pancreatic amylase helps in digestion of starch. 5. Name the physical process which is actually responsible for the gaseous exchange. Diffusion is responsible for the gaseous exchange. 6. Why is it essential, to match the blood group of the 'donor1 and the 'receiver' person before arranging transfusion of blood? A person gives test as a 'universal donor'. Which group of blood will be acceptable to him for receiving blood transfusion? Blood group of the donor should always be matched with that of recipient because in case of mismatched blood, the antibodies in the plasma of the recipient react with antigen of the donor leading to agglutination (clumping) of blood, which may lead to death. The blood group of the person is 'O'. Only the blood of group 'O' can be transfused in his body as his blood has both antibodies 'a' and 'b'. 7. Explain why more amount of energy is produced during aerobic respiration? Aerobic respiration causes complete breakdown of glucose into CO2 and H2O whereas, anaerobic respiration involves incomplete breakdown of glucose. Thus, more amount of energy is released during aerobic respiration than anaerobic respiration. 8. Respiration is the vital function of the body. Justify? The process of respiration is a vital function of the body because www.pioneermathematics.com S.C.O. - 326, Sector 40 D, CHD. Phone: 9815527721, 4617721 12
(i) It helps in providing oxygen, which is vital for life. Oxygen rich air enters the body through the process of breathing, (ii) Oxygen is used up during cellular respiration, which produces large amount of energy which is utilised for various vital activities, (iii) During oxidation of food, CO2 a highly toxic gas is released, which is expelled through the process of respiration, (iv) During excessive need of energy, rate of respiration increases to provide extra energy, (v)in the absence of oxygen also, energy can be produced by anaerobic respiration. Life Processes {Chapter Test} M:M: 30 M: Time: 40Mins. 1. In an experiment, a test tube containing pieces of bread (powdered), saliva is added to it. What will be the result? [1] Solution: Salivary amylase present in saliva will breakdown starch of bread into glucose. 2. Rishabh told his mother that various pipe lines transport the gases in our body. Based on his view, describe the transport and mechanism of exchange of gases in our body. [5] Solution: The diagram showing transport and exhange of gases in human body is shown below www.pioneermathematics.com S.C.O. - 326, Sector 40 D, CHD. Phone: 9815527721, 4617721 13
The arteries carry oxygenated blood {except pulmonary artery) while veins carry deoxygenated blood (except pulmonary vein). Thus, the gases O2 and CO2 are transported in the body. Diagram of working circulation of blood and exchange of gases is shown below 3. Rohan is class Xth student. His mother thinks that blood is symmetrically flows in the body. How Rohan will convince his mother, about the blood circulation? [3] Solution: Function of Heart Heart is the pumping organ of body, it receives deoxygenated blood and supply oxygenated blood to all body parts. Structure of human heart is shown below www.pioneermathematics.com S.C.O. - 326, Sector 40 D, CHD. Phone: 9815527721, 4617721 14
Process of Circulation (i) The superior and inferior vena cava bring deoxygenated blood from all body parts (upper and lower respectively) to the right auricle of heart (ii) The blood is passed to right ventricle by auricular contraction and pulmonary artery takes this blood to lungs after ventricle contracts, for oxygenation. (iii) The oxygenated blood reaches the left atrium by pulmonary vein from where it reaches left ventricle after its contraction. (iv) Aorta takes blood to all body parts, where it gets deoxygenated again by exchange of gases between cells and blood, (v) The time when oxygenated and deoxygenated blood reaches the heart is simultaneous. For working diagram-refer to fig in Solution: 35 4. How is transportation of water in xylem tissue different from translocation of food in phloem tissue? [2] Solution: Energy is not required in the transportation of water in xylem tissue, whereas translocation of food requires energy in the form of ATP 5. (a) Name the process in plants where water is lost as water vapour, (b) What is the primary requirement for pancreatic enzymes to act? [2] Solution: (a) In the process of transpiration, water is lost as water vapour. www.pioneermathematics.com S.C.O. - 326, Sector 40 D, CHD. Phone: 9815527721, 4617721 15
(b) Pancreatic enzymes (trypsin and lipase) act only in alkaline medium. 6. Explain the process of breakdown of glucose in a cell in (a) presence of oxygen (b) absence of oxygen. [2] Solution: Glucose is the ultimate source of energy for living organisms. During respiration, it breaks down into CO2, H2O and releases energy. Depending on the availability of O2, the respiration may be aerobic or anaerobic in nature. In presence of O2, the energy released is higher in amount. 7. What are the different ways in which glucose is oxidised to provide energy to provide energy in various organism? [3] Solution: (i) The first step is the breakdown of 6-carbon molecule glucose into a 3-carbon molecule pyruvate. This process takes place in the cytoplasm. (ii) Further oxidation of pyruvate occurs in the following ways (a) In yeast, pyruvate is converted into ethanol and carbon dioxide in the absence of oxygen. 6carbon molecule 3carbon molecule No oxygen 2carbon molecule 2 carbon dioxide Glucose Pyruvate Ethanol CO Energy (b) In our skeletal muscles, pyruvate is converted into lactic acid, when there is deficiency of oxygen. 2 6carbon molecule No oxygen 3carbon molecule 2carbon molecule carbon dioxide Glucose Pyruvate Lactic acid CO Energy www.pioneermathematics.com S.C.O. - 326, Sector 40 D, CHD. Phone: 9815527721, 4617721 16
(c) The aerobic oxidation of pyruvate occurs in the mitochondria; the 3-carbon pyruvate molecule gives rise to three molecules of carbon dioxide and water. Mitrochondria 6carbon molecule 3carbon molecule oxygen 2 carbon 2 dioxide Glucose Pyruvate CO H O Energy 8. (a) What is transpiration pull? (b) Why transpiration pull is necessary for plants? [2] Solution: (a) Water vapour evaporates from the leaf and creates a kind of suction (towards upward) with in the xylem which in turn draws water upward from the root system. This is known as transpiration pull. (b) Transpiration pull is necessary for plants because it helps in the absorption and upward movement of water and minerals from roots to the leaves. 9. Describe double circulation in human beings. Why is it necessary? [5] Solution: In human beings, the blood goes through the heart twice during each cycle i.e., the blood passes through the human heart two times to supply once to the whole body. So, it is called double circulation of blood. The double circulation of blood includes (i) Systemic circulation (ii)pulmonary circulation (i) Systemic Circulation It supplies oxygenated blood from left auricle to left ventricle, thereby pumping it to various body parts. The deoxygenated blood is collected from the various body organs by the veins to pour the same into vena cava and finally into the right-atrium (auricle). Right-atrium transfers the blood into the right ventricle. www.pioneermathematics.com S.C.O. - 326, Sector 40 D, CHD. Phone: 9815527721, 4617721 17
(ii) Pulmonary Circulation The deoxygenated blood is pushed by the right ventricle into the lungs for oxygenation. The oxygenated blood is brought back to left-atrium of the human heart. From left-atrium, the oxygenated blood is pushed into the left ventricle. The left ventricle pumps oxygenated blood into aorta for systemic circulation. Necessity Double circulation of blood in human beings prevents the mixing of oxygenated and deoxygenated blood. This allows a highly efficient supply of oxygen to the body and provides constant energy to organisms to maintain their body temperature. 10. Megha told her mother that various metabolic wastes are synthesised in our body. Her mother feared about this. What are the structure responsible to get rid of these wastes? What role do nephrons play in excretion? Give composition of urine. [5] Solution: Kidney is responsible to get rid of the wastes of the body. It is the main organ of human excretory system. Excretion is important to remove the metabolic wastes from the body, which might otherwise be harmful and cause diseases. The excretion of wastes such as water, salts, etc., through skin helps to maintain body temperature. Nephrons are the blood filtering units of kidney. Each nephron contains a long coiled www.pioneermathematics.com S.C.O. - 326, Sector 40 D, CHD. Phone: 9815527721, 4617721 18
tube connected to Bowman's capsule (cup-shaped) at one end and to collecting duct at other end. Blood capillaries (glomerulus) in the Bowman's capsule filter blood and transfer the reabsorbable substances to the coiled tubule back. These substances include glucose, amino acids, salts, water, etc. Composition of urine Urea, waste salts and excessive water. www.pioneermathematics.com S.C.O. - 326, Sector 40 D, CHD. Phone: 9815527721, 4617721 19