Q 1. How are water and minerals absorbed by the plant?
Solution
In the roots, cells in contact with the soil actively take up the ions. It creates a difference in the concentration of these ions between roots of soil. To eliminate this difference, water moves into the roots from the soil. Thus, water and minerals are absorbed by the plants.
Q 2. You have visited a zoo where you have observed that a fish is respiring with a faster rate whereas the crocodile is not. Explain the reason behind it.
Solution
Aquatic animals like fish absorb O2 in dissolved form and since the amount of dissolved O2 is fairly low compared to amount of O2 in the air, the rate of breathing in aquatic organism is faster than that of crocodile.
Q 3. What happens to glucose that enters the nephron along with the filtrate?
Solution
Glucose that enters the nephron along with the filtrate after passing through the glomerulus, passes from the tubule of nephron where it is selectively reabsorbed and sent back to blood.
Q 4. What is site for the breakdown of pyruvate to release carbon dioxide, water and energy in our bodies?
Solution
Breakdown of pyruvate takes place in mitochondria and results in the release of carbon dioxide, water and energy
Q 5. How an artery is different from the vein?
Solution
Artery Vein i. Carry oxygenated blood. ii. Walls are thick. iii. Carry blood from heart to various body parts. i. Carry deoxygenated blood. ii. Walls are thin. iii. Carry blood from various body parts to heart.
Q 6. In the Lungs: What substance is taken into the body? What substance is removed from the body?
Solution
O2 CO2
Q 7. How are the alveoli designed to maximize the exchange of gases ?
Solution
Large numbers of alveoli in the lungs provides a very large surface area for the exchange of gases. Walls of alveoli contain an extensive network of blood vessels. Walls of alveoli are extremely thin and made of single layer of cells. (any two)
Q 8. A scientist while performing an experiment, first places an RBC in an concentrated salt solution and then in distilled water. Write the observation in both the cases.
Solution
In the first case, when RBC is placed in the concentrated salt solution it will shrink due to loss of plasma (water) into the surrounding solution. While in distilled water, it will regain its shape by becoming turgid due to absorption of water.
Q 9. How opening and closing of stomata is regulated in the leaves of plants?
Solution
The opening and closing of stomata is controlled by the guard cells. When water flows into the guard cells, they swell up and the curved surface causes the stomata to open. When the guard cells loses water, they shrink and become flacid and straight thus closing the stomata.
Q 10. What happens when two non matching blood groups are mixed?
Solution
When two different types of bloods are mixed together, it causes blood clumping or agglutination of blood. When two different blood groups are combined the antigen present in one group binds with the antibodies of other blood group and results in agglutination of blood which leads to rupture of erythrocytes which may be fatal for the patient.
Q 11. What will happen if the blood is deficient in haemoglobin?
Solution
If the blood is deficient in the haemoglobin then less amount of O2 reaches to tissues due to which less energy will be released as less O2 bind with the haemoglobin.
Q 12. A kind of blood cell engulf the foreign particles that enter in our body. Name it and why it do so?
Solution
Leucocytes produces antibodies which kill the harmful germs that enter our body.
Q 13. Name the products formed after complete digestion of carbohydrates, proteins and fats in small intestine.
Solution
In small intestines, the intestinal juice contains a number of enzymes which complete the digestion process by converting complex carbohydrates into glucose, proteins into amino acids and fats into fatty acids and glycerol.
Q 14. How does HCl in the human stomach help in digestion of food?
Solution
1. HCl helps in activating pepsin, a protein-digesting enzyme. 2. It kills any germs which may have entered the body along with food.
Q 15. (i) Why are valves needed in the heart? (ii) Leakage of blood from vessels reduces the efficiency of pumping system. How is the leakage prevented?
Solution
(i) Valves ensure that blood does not flow backward when the atria or ventricles contract. (ii) To avoid leakage blood has platelet cells which circulate around the body and plug the leakage by clotting the blood at the point of injury.
Q 16. What is contraction and relaxation of the wall of the digestive tract called?
Solution
The contraction and relaxation of the wall of the digestive tract is called peristalsis.
Q 17. How water and minerals are transported in the plants?
Solution
Water and minerals in plants are absorbed from soil by the roots of the plants and transported to various parts of the plants through xylem vessels due to root pressure and transpiration.
Q 18. What is cardiac cycle? Name its various events.
Solution
Cardiac cycle is the sequence of events which occur from beginning of one heartbeat to the beginning of next. Various phases are:- atrial systole, ventricular systole and complete diastole
Q 19. Explain the digestion in stomach.
Solution
The gastric glands in the stomach secrete: (i) HCl – It kills the bacteria ingested with food and makes the medium of food acidic so as to facilitate the action of the enzyme pepsin. (ii) Pepsin – It helps to digest proteins. (iii) Mucus – It protects the inner lining of the stomach from the action of HCl.
Q 20. Which organelle is associated with production of energy by aerobic respiration?
Solution
Mitochondria are associated with production of energy by aerobic respiration.
Q 21. A cup shaped structure in the nephron receives blood through a network of capillaries. What is this network of capillaries known as and what is its main function?
Solution
The bundle of capillaries constitutes the glomerulus. It helps in the filtration of blood.
Q 22. Most of the CO2 produced in a tissue enters the red blood cells by diffusion. What happens to this CO2?
Solution
Most of the CO2 produced in a tissue enters the RBC’s of blood by diffusion. RBC’s consist of a pigment known as haemoglobin which binds with CO2 and get transported to the lungs through blood from where it is released out through nostrils.
Q 23. Nephron is responsible for the formation of urine. Explain the structure of nephron.
Solution
Nephron is the structural unit of kidney which consists of a long tubule. One end of the tubule is connected to Bowman’s capsule, a cup shaped structure, followed by a tubular part consisting of proximal convoluted tubule, loop of Henle and distal convoluted tubule. Bowman’s capsule contains a bundle of blood capillaries called glomerulus which filter the blood. The function of tubular part on the other hand is selective reabsorption of useful substances.
Q 24. Leaves of a healthy potted plant were coated with vaseline. Will this plant remain healthy for long? Give reasons.
Solution
The plant will not remain healthy for a long time because: i. It would not get oxygen for respiration. ii. It would not get carbon dioxide to carry out photosynthesis. iii. The upward movement of water and minerals would be hampered due to lack of transpiration.
Q 25. What happens to the plant cell when we keep it in the hypotonic solution?
Solution
When we keep plant cell in the hypotonic solution it absorbs water from the surroundings and becomes more turgid.
Q 26. If the kidney failure cannot be treated by drugs or dialysis what advice is given to the patient?
Solution
In situation, where kidney failure cannot be treated by drugs or dialysis, the patient is advised for kidney transplantation. The donor for the kidney is preferably a close relative of the patient as it reduces the chances of rejection.
Q 27. A women is feeling breathlessness. What is done to help her to overcome
breathing problem?
Solution
She should be given oxygen mask to facilitate breathing and in serious cases, patients are put on a machine called ventilator.
Q 28. Explain the mechanism of gaseous exchange during respiration.
Solution
1) In human beings, alveoli in lungs provide a surface where the exchange of gases takes place. 2) Alveoli are surrounded by blood capillaries through which O2 diffuses from alveoli to blood and from blood CO2 diffuses in lungs. 3) O2 further gets transported to all the cells in the body.
Q 29. Major amount of water is selectively reabsorbed by the tubular part of nephron in humans. What are the factors on which the amount of water reabsorbed depends?
Solution
The amount of water reabsorbed depends on : (i) The excessive amount of water present in the body. (ii) The amount of dissolved wastes to be excreted out from the body.
Q 30. Two green plants are kept separately in oxygen free containers, one in the dark and the other in continuous light. Which one will live longer? Give reasons.
Solution
Plant kept in continuous light will live longer, because it will be able to produce oxygen required for its respiration by the process of photosynthesis.
Q 31. Which instrument is used to measure blood pressure?
Solution
Sphygmomanometer is used to measure blood pressure
Q 32. A person is suffering from dehydration. How do kidney help in conservation of water?
Solution
When water content is low in body, the tubules of nephron in kidney absorb more water and ions and send it back to the body to prevent dehydration.
Q 33. What is excretion? How do unicellular organisms remove their wastes?
Solution
The biological process of removing harmful metabolic wastes from the body is called excretion. Unicellular organisms remove their wastes through simple diffusion.
Q 34. (a) Explain the events which take place during photosynthesis. (b) Which test is done to prove presence of starch in leaves?
Solution
(a)Photosynthesis takes place in the following three steps: (i) Absorption of sunlight energy by chlorophyll. (ii) Conversion of light energy into chemical energy, and splitting of water into hydrogen and oxygen using light energy. (iii) Reduction of carbon dioxide by hydrogen to form carbohydrate like glucose by utilizing the chemical energy. (b) Iodine test is done to prove the presence of starch in leaves. The starch present in leaves give blue-black colour with iodine solution.
Q 35. Name the enzyme found in saliva. State the role of saliva in the digestion of food.
Solution
Salivary amylase is the enzyme found in saliva. Role of saliva : (1) Softening of food for easy crushing by teeth. (2) It contains the enzyme ptyalin (salivary amylase ) that convert starch into sugar. (Any one role)
Q 36. Suppose you went for a marriage last night. When you reached home, you complained about acidity. Explain the reason for acidity.
Solution
When we eat more food or more spicy food, our digestive system has to work more by releasing more amount of enzymes for digestion. Stomach releases more HCl to digest more food, because of which a lot of acid is formed, which may lead to acidity. Acidity can also cause diarrhoea, i.e. vomiting and loose motions.
Q 37. Suppose you hold your breath. After maximum expiration for 10 sec, would there be any exchange of respiratory gases occurring in lungs during the period? Give reason.
Solution
Yes, there will be exchange of gases all the time because even after forceful respiration some amount of air still remains in the lungs.
Q 38. In which form food is transported in the plants?
Solution
Food is transported in the plants in the form of sucrose.
Q 39. An extra cellular fluid helps in the absorption of fat and production of antibodies. Name it and write its function.
Solution
Lymph is an extra cellular fluid which produces antibodies to fight against inflections. It also helps in absorption of fat and drains excess fluid from extracellular space into the blood.
Q 40. Explain the significance of peristaltic movement that occurs all along the gut during digestion.
Solution
It is necessary to move the food in a regulated manner along the digestive tube so that it can be processed properly in each part. The lining of canal has muscles that contract rhythmically in order to push the food forward.