CBSE Class 10 Science Important Questions Chapter 6 Life Processes Part 2

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2 Marks Questions

1. What is common for Cuscuta, ticks and leeches?

Ans. Cuscuta, ticks and leeches, all has parasitic mode of nutrition, and they harm their host while taking nutrition.

2. What advantage over an aquatic organism does a terrestrial organism have with regard to obtaining oxygen for respiration?

Ans. Adaptation of terrestrial organism over aquatic organism for efficient uptake of oxygen from air –

(i) Increased respiratory surface area.

(ii) Very fine and delicate surface for easy exchange of oxygen and carbon – dioxide.

(iii) Placement of respiratory surface within the body for protection (iv) Mechanism for moving the air in and out of respiratory surface where the oxygen is absorbed.

3. Differentiate between single and double circulation found in vertebrates.

Ans.

Single and Double Circulation Found in Vertebrates
Single and double circulation found in vertebrates

Single Circulation

Double Circulation

1.In this, blood passes only once through the heart in one complete cycle

Blood passes, twice through the heart in one complete

2.Heart has only deoxygenated blood

Heart has both oxygenated and deoxygenated blood

It is less efficient

It is more efficient

4. Name the substrates for the following enzymes

a) Trypsin

b) Amylase

c) Pepsin

d) Lipase

Ans. a) Protein

b) Starch

c) Protein

d) Lipids

5. What are the two stages in photosynthesis?

Ans. Two stages in photosynthesis –

a) Light reaction – Light energy breaks up water molecular into hydrogen and oxygen, called photolysis of water

b) Dark reaction – Fixation and conversion of carbon – dioxide into a simple carbohydrates glucose.

6. What is the difference between arteries & veins?

Ans.

Arteries & Veins
Arteries & veins

Arteries

Veins

1. It carries blood away from the heart.

It carries blood towards the heart.

2. They are thin walled

They are thick walked

3. They have narrow lumen

They have wide lumen

4. Pressure is high

Pressures is low

5. It carries oxygenated blood

It carries Deoxygenated blood

7. What is villi? What are its functions?

Ans. Finger like projection present in the inner lining of small intestine are called villi. They increase the surface area for the absorption of digested food in the small intestine.

8. What type of respiration takes place in human muscles during vigorous exercise and why?

Ans. During vigorous exercise, anaerobic respiration takes place in human muscles. During exercise our energy requirement increase, so our striated muscles start respiring anaerobically in the lack of oxygen and producers ATP molecules.

9. How is opening and closing of stomata regulated?

Ans. The closing and openings of the stomata is regulated by guard cells. When the guard cells swell or turgid due to entry of water, the stomata are opened. The guard cells shrink due to loss of water the stomata get closed.

10. State two vital functions of kidney.

Ans. Function of kidney are –

1) It maintains water balance in the body tissues.

2) It controls calcium levels in the blood to maintain healthy bones.

11. Differentiate between aerobic and anaerobic respiration.

Ans.

Aerobic and Anaerobic Respiration
Aerobic and anaerobic respiration

Aerobic Respiration

Anaerobic Respiration

a) It occurs in the presence of oxygen

a) It occurs in the absence of oxygen

b) It occurs in cytoplasm and in the mitochondria

b)It occurs in cytoplasm

C) Complete breakdown of glucose

c) Incomplete breakdown of glucose

d) End products are

d) End products are

12. Meat is easier to digest as compared to grass. Why?

Ans. It is easier to digest meat because our digestive juices contain enzymes which can easily digest meat but our body does not digest cellulose which is a main component of grass.

13. Differentiate between transport of materials in xylem & phloem Ans.

Transport of Materials in Xylem
Transport of Materials in xylem

Xylem

Phloem

a) It transport water and minerals

a)It transport food meterials

b) Transport of substances in upwards direction only.

b) Transport of substances in both directions upward & downward

14. What is the role of glomerulus in kidney?

Ans. Glomerulus is a group of capillaries present in the cup like Bowman ‘s capsule. It receives blood from renal artery which brings excretory wastes from body to the kidney. It filters water, salts, glucose, urea, the nitrogen containing end products of proteins and yellow bile compounds from the liver.

15. Why is it essential to match the blood groups of donors and receiver person before arranging transfusion of blood?

Ans. RBC’s of blood carries antigen as well as antibody. If blood is not matched before transfusion then blood of receiver start producing antibodies against donor blood and destroys blood cells, this causes deficiency of blood and causes death.

16. Why is it necessary to separate oxygenated & deoxygenated blood in mammals & birds?

Ans. Separation of oxygenated and deoxygenated blood allows good supply of oxygen to the body. This system is useful in animals that have high energy requirement Mammals and birds constantly need oxygen to get energy to maintain constant body temperature

17. Why the walls of trachea are supported by cartilaginous rings? Ans. The trachea is supported by cartilaginous rings which prevent the collapsing even when there is not much air in it.

18. What are the raw materials for photosynthesis?

Ans. Raw materials for photosynthesis are –

a) Carbon – dioxide

b) Water

c) Chlorophyll and Sunlight

19. What is the role of diaphragm during inhalation and exhalation? Ans. Diaphragm changes its shape during inhalation and exhalation and increases and decreases volume of thoracic cavity respectively. This causes entry and expel of air from lungs.

20. What is the advantage of four chambered of heart?

Ans. The right and left parts are separated by a septum to prevent oxygenated and deoxygenated blood from mixing. This fulfils the constant use of energy to maintain their body temperature. Their energy needs are high, which are fulfilled efficiently because of non – mixing of oxygenated & deoxygenated blood.

21. Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans?

Ans. As in multicellular organisms, all the cells are not in direct contact with environment, simple diffusion does not meet the requirement of all the body cells.

22. What criteria do we use to decide whether something is alive? Ans. All the living organism must have movement at molecular levels along with respiration and other life process like nutrition, respiration, transportation and excretion to be called alive.

23. What is the function of digestive enzymes?

Ans. Enzymes break-down the various complex components of food into simple and soluble components so that they can be absorbed easily.

24. How are the lungs designed in human beings to maximize the area for exchange of gases?

Ans. In lungs, the bronchioles terminate in balloon-like structures called alveoli. The alveoli contain network of blood capillaries that increase the surface area for exchange of gases.

25. What is the role of saliva in the digestion of food?

Ans. The saliva contains an enzyme called salivary amylase that breaks down starch which is complex molecule into glucose.

26. While eating you are advised not to talk why you are advised so? Ans. We are advised so because while eating some food particles might enter the wind pipe which can lead to choking.

27. We say that movement is a characteristic of living organisms but we always don’t see visible movements in plants. Comment.

Ans. We always don’t see visible movements in plants. It does not mean that they are not alive.

Molecular movements take place in their body.

28. If a person is working on a treadmill in a gymnasium, will it effect his rate of breathing? How?

Ans. Yes, it will affect his rate of breathing. The rate of breathing will become fast to supply more oxygen to meet the increased demand of energy.

29. If you compare your rate of breathing by feeling your chest movement with the number of times a fish opens and closes its mouth. Which will be higher and way?

Ans. The number of times a fish opens and closes its mouth will be higher as the amount of dissolved oxygen in water is fairly low compared to the amount of oxygen in the air. Therefore, rate of breathing in aquatic organisms is much faster than in terrestrial organisms.

30. Mucus is not used for churning the food or digesting it. Then why is it secreted in the stomach?

Ans. Mucus is secreted in the stomach to protect its inner lining form being damaged by HCI. Excessive secretion of HCI can damage the lining and lead to peptic ulcer.

31. In the process of Photosynthesis food A is prepared which gets converted into food B. What are A and B? Why is A converted to B?

Ans. Food A is glucose and food B is Starch.

A is converted to B as B is insoluble form of carbohydrate. It is more compact and hence, suitable for storage.

32. When we are asleep we are not performing any activity still our life processes are going on. Why?

Ans. “The maintenance functions of living organisms must go on even when they are not doing anything particular.” That is why the life processes are going on even while we are asleep or not performing any activity.

33. What will be the outcome if a farmer floods his field every day?

Ans. Respiration of plants will be affected because the oxygen present in the interspaces of the soil will be replaced by water.

34. Name the respiratory organs of (i) fish (ii) mosquito (iii) earthworm.

Ans. Fish - gills

Mosquito - Trachea (air tubes)

Earthworm - moist skin

35. Due to availability of less water, how does the plant cope up with lack of water in desert conditions?

Ans. They open their stomata at night and stomata remain closed during day time, to conserve moisture.

36. After a vigorous exercise, you may experience cramps in your leg muscles. Why does this happen?

Ans. The sudden build-up of lactic acid in our muscles during vigorous, exercise, causes muscular cramps in our leg muscles.

37. What will happen if carbon monoxide combines with hemoglobin?

Ans. If the hemoglobin binds with carbon monoxide strongly, the oxygen will not be carried with blood leading to death of the organism.

38. Chloroplast are called energy convertors. Explain.

Ans. Chloroplasts are called energy convertors because they trap the solar energy and convert it into chemical energy.

39. Why is the rate if breathing much faster in aquatic organisms than those of terrestrial organisms?

Ans. The aquatic organisms obtain oxygen dissolved in water. As compared to air, the availability of oxygen in water is fairly low. Hence, the aquatic organisms have to breathe faster as compared to the terrestrial organisms.

40. Why are glomeruli considered as dialysis bags?

Ans. The main fimetion performed by the glomeruli is selective filtration. They filter small molecules containing glucose, salts, urea, and liquid senim. Etc. The large molecules such as proteins remain in blood. Thus, glomenili of the kidneys function as dialysis bags.

41. Autotrophs synthesis food for the living world. Justify this statement in one sentence only interconnecting autotrophs and heterotrophs.

Ans. The food producers are autotrophs and all the heterotrophs consume the food produced by the autotrophs directly or indirectly.

42. Veins and arteries catty blood. Which of these carry blood?

a) Away from the heart?

b) Back to the heart?

Ans. a) Arteries carry blood away from the heart.

b) Veins carry blood back to the heart.

43. Which of the organs perform the following functions in humans? i. Absorption of food. ii. Absorption of water

Ans. i. Absorption of food takes place in small intestine.

ii. Large intestine

44. Name the areas in a woody stem through which respiratory exchange of gases take place.

Ans. In woody stem, the bark has lenticels for gaseous exchange.

45. Why doesn’t the lungs collapse even after forceful expiration?

Ans. Even after forceful expiration to the maximum capacity, some amount of air remains in the lungs, known as residual volume. So, the lungs doesn’t collapse even after forceful expiration.

46. “If there were no algae there would be no fish in the sea”. Comment.

Ans. Algae produce 02 as a result of photosynthesis. l’his oxygen is utilized by the fishes in the sea for carrying out respiration. If there were no algae, no oxygen would have been produced. Thus, fishes might have died.

47. Why is the process of diffusion insufficient to meet the oxygen requirement of human beings?

Ans. The process of diffusion for carrying 02 to all parts of the body is not sufficient for larger multicellular organisms like human beings. Hence, respiratory pigment hemoglobin takes up oxygen from the air and carry it to all the parts of our body through blood.

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