NCERT Exemplar for Class 10 Science Chapter 6 - Life Processes (Book Solutions)

Multiple Choice Questions

1. Which of the following statements about the autotrophs is incorrect?

(a) They synthesise carbohydrates from carbon dioxide and water in the presence of sunlight and chlorophyll

(b) They store carbohydrates in the form of starch

(c) They convert carbon dioxide and water into carbohydrates in the absence of sunlight

(d) They constitute the first trophic level in food chains.

Ans: The answer is (c) They convert carbon dioxide and water into carbohydrates in the absence of sunlight

Explanation: To convert carbon dioxide and water into carbohydrates, they require sunshine.

2. In which of the following groups of organisms, food material is broken down outside

the body and absorbed? 

(a) Mushroom, green plants, Amoeba

(b) Yeast, mushroom, bread mould

(c) Paramecium, Amoeba, Cuscuta

(d) Cuscuta, lice, tapeworm

Ans: The answer is (b) Yeast, mushroom, bread mould

Explanation: Saprophytes are organisms that break down food outside of their bodies and consume it. Yeast, mushrooms, and bread mould are examples of saprophytes.

3. Select the correct statement

(a) Heterotrophs do not synthesise their own food

(b) Heterotrophs utilise solar energy for photosynthesis

(c) Heterotrophs synthesise their own food

(d)Heterotrophs are capable of converting carbon dioxide and water into carbohydrates

Ans: The answer is (a) Heterotrophs do not synthesise their own food

Explanation: Heterotrophs are food-dependent on either Phototrophs or other species.

4. Which is the correct sequence of parts in the human alimentary canal?

(a) Mouth → stomach → small intestine → oesophagus → large intestine

(b) Mouth →oesophagus → stomach → large intestine → small intestine

(c) Mouth → stomach → oesophagus → small intestine → large intestine

(d) Mouth → oesophagus → stomach → small intestine → large intestine

Ans: The answer is (d) Mouth → oesophagus → stomach → small intestine → large

intestine

5. If salivary amylase is lacking in the saliva, which of the following events in the mouth cavity will be affected?

(a) Proteins breaking down into amino acids

(b) Starch breaking down into sugars

(c) Fats breaking down into fatty acids and glycerol

(d) Absorption of vitamins

Ans: The answer is (b) Starch breaking down into sugars

Salivary Amylase, a digestive enzyme, breaks down starch into simpler sugars and aids digestion. As a result, if salivary amylase is deficient, starch breakdown will be a breakdown.

6. The inner lining of the stomach is protected by one of the following from hydrochloric acid. Choose the correct one 

(a) Pepsin

(b) Mucus

(c) Salivary amylase

(d) Bile

Ans: The answer is (b) Mucus

The inner lining of the stomach is protected by Mucus from hydrochloric acid

7. Which part of the alimentary canal receives bile from the liver?

(a) Stomach

(b) Small intestine

(c) Large intestine

(d) Oesophagus

Ans: The answer is (b) Small intestine

Bile goes to the small intestine from the gallbladder through hepta pancreatic duct.

8. A few drops of iodine solution were added to rice water. The solution turned blue-black in colour. This indicates that rice water contains

(a) complex proteins

(b) simple proteins

(c) fats

(d) starch

Ans: The answer is (d) starch

Amylose and Amylopectin are the two components of starch. Amylose interacts with iodine to generate a blue colour complex when iodine is added to starch-containing water. When Iodine is added to this solution, it becomes blue-black, indicating the presence of starch in the rice water.

9. In which part of the alimentary canal food is finally digested?

(a) Stomach

(b) Mouth cavity

(c) Large intestine

(d) Small intestine

Ans: The answer is (d) Small intestine

Explanation: Although the primary digestive process takes place in the mouth and stomach, the majority of digestion takes place in the small intestine, and the large intestine digestion process does not occur.

10. Choose the function of the pancreatic juice from the following

(a) trypsin digests proteins and lipase carbohydrates

(b) trypsin digests emulsified fats and lipase proteins

(c) trypsin and lipase digest fats

(d) trypsin digests proteins and lipase emulsified fats

Ans: The answer is (d) trypsin digests proteins and lipase emulsified fats

Explanation: Lipase breaks down emulsified lipid molecules into fatty acids and glycerol, while Trypsin breaks down proteins into polypeptides.

11. When air is blown from the mouth into a test tube containing lime water, the lime

water turned milky due to the presence of

(a) oxygen

(b) carbon dioxide

(c) nitrogen

(d) water vapour

Ans: The answer is (b) carbon dioxide

Explanation: Carbon dioxide reacts with lime water and turns the lime water milky.

12. The correct sequence of anaerobic reactions in yeast is correct sequence of anaerobic reactions

(a)Glucose$\xrightarrow{\text{cytoplasm}}$Pyruvate$\xrightarrow{\text{mitochondria}}$Ethanol + Carbon Dioxide

(b)Glucose$\xrightarrow{\text{cytoplasm}}$Pyruvate$\xrightarrow{\text{cytoplasm}}$Lactic acid

(c)Glucose$\xrightarrow{\text{cytoplasm}}$Pyruvate$\xrightarrow{\text{mitochondria}}$Lactic acid

(d)Glucose$\xrightarrow{\text{cytoplasm}}$Pyruvate$\xrightarrow{\text{cytoplasm}}$Ethanol + Carbon Dioxide

Ans: The answer is d)

Explanation: In Yeast cytoplasm, Glucose is a breakdown in anaerobic conditions to produce Pyruvate which is the further breakdown to Ethanol and carbon-di-oxide

13. Which of the following is most appropriate for aerobic respiration?

(a) Glucose\xrightarrow{mitochondria}Pyruvate\xrightarrow{cytoplasm} CO2 + H2O +

Energy

(b) Glucose\xrightarrow{cytoplasm}Pyruvate\xrightarrow{mitochondria}CO2 + H2O +

Energy

(c) Glucose\xrightarrow{cytoplasm}Pyruvate + Energy\xrightarrow{mitochondria}CO2

+ H2O

(d) Glucose\xrightarrow{cytoplasm}Pyruvate + Energy\xrightarrow{mitochondria}CO2

+ H2O + Energy

Ans: Answer is Option (B)

14. Which of the following statement(s) is (are) true about respiration?

(i) During inhalation, ribs move inward and the diaphragm is raised

(ii) In the alveoli, exchange of gases takes place i.e., oxygen from alveolar air diffuses

into blood and carbon dioxide from the blood into the alveolar air

(iii) Haemoglobin has a greater affinity for carbon dioxide than oxygen

(iv) Alveoli increase surface area for the exchange of gases

(a) (i) and (iv)

(b) (ii) and (iii)

(c) (i) and (iii)

(d) (ii) and (iv)

Ans: The answer is (d) (ii) and (iv)

Explanation: Statement i) is wrong because ribs move outward and the diaphragm is lowered during inhalation. Similarly Option iii) is wrong because Hemoglobin has a greater affinity for Oxygen than CO2.

15. Which is the correct sequence of air passage during inhalation?

(a) Nostrils →larynx →pharynx →trachea →lungs

(b) Nasal passage →trachea →pharynx →larynx →alveoli

(c) larynx →nostrils →pharynx →lungs

(d) Nostrils →pharynx →larynx →trachea →alveoli

Ans:The answer is (d) Nostrils →pharynx →larynx →trachea→alveoli

Explanation: Through the nose, air enters the respiratory system, passing through the pharynx, larynx, trachea, and alveoli. Following inhalation, the diaphragm and intercoastal muscles contract, coupled with the thoracic muscles expanding, allowing air to enter the lungs.

16. During respiration exchange of gases take place in

(a) trachea and larynx

(b) alveoli of lungs

(c) alveoli and throat

(d) throat and larynx

Ans: The answer is (b) alveoli of lungs

Explanation: The trachea and larynx offer a pathway for air to travel across. The Alveoli of the lungs are where gas exchange takes place. Oxygen diffuses into the bloodstream through alveoli, while carbon dioxide is expelled.

17. Which of the following statement (s) is (are) true about the heart?

(i) The left atrium receives oxygenated blood from different parts of the body while

the right atrium receives deoxygenated blood from the lungs

(ii) Left ventricle pumps oxygenated blood to different body parts while the right

ventricle pumps deoxygenated blood to the lungs

(iii) Left atrium transfers oxygenated blood to the right ventricle which sends it to

different body parts

(iv) The right atrium receives deoxygenated blood from different parts of the body

while the left ventricle pumps oxygenated blood to different parts of the body

(a) (i)

(b) (ii)

(c) (ii) and (iv)

(d) (i) and (iii)

Ans: The answer is (c) (ii) and (iv)

Explanation: The left side of the heart is where oxygenated blood flows, whereas the right side is where deoxygenated blood circulates. The atrium receives blood, while the ventricle pumps it out of the heart.

18. What prevents the backflow of blood inside the heart during contraction?

(a) Valves in the heart

(b) Thick muscular walls of ventricles

(c) Thin walls of atria

(d) All of the above

Ans: The answer is (a) Valves in the heart

Explanation: The walls of the heart are only responsible for pumping blood; they are not responsible for preventing blood from flowing backwards into the heart during contraction.

19. Single circulation i.e. blood flows through the heart only once during one cycle of

passage through the body, is exhibited by

(a) Labeo, Chameleon, Salamander

(b) Hippocampus, Exocoetus, Anabas

(c) Hyla, Rana, Draco

(d) Whale, Dolphin, Turtle

Ans: The answer is (b) Hippocampus, Exocoetus, Anabas

Explanation: In Option a) Chameleon is a reptile and Salamander is an amphibian which has 3 chambered hearts and shows partial double circulation. In Option c) all are Amphibians and they show partial double circulation. In option d) Whale is a mammal but turtle is a reptile hence option d) is wrong.

20. In which of the following vertebrate group/groups, the heart does not pump oxygenated blood to different parts of the body?

(a) Pisces and amphibians

(b) Amphibians and reptiles

(c) Amphibians only

(d) Pisces only

Ans: The answer is (d) Pisces only

Explanation: This is due to the heart's solitary circulation, which pumps deoxygenated blood from all parts of the body into it. It is pumped from the heart to the gills, where it is oxygenated and distributed to all parts of the body. As a result, Pisces will not be receiving oxygenated blood.

21. Choose the correct statement that describes arteries.

(a) They have thick elastic walls, blood flows under high pressure; collect blood from

different organs and bring it back to the heart

(b) They have thin walls with valves inside, blood flows under low pressure and carries

blood away from the heart to various organs of the body

(c) They have thick elastic walls, blood flows under low pressure; carry blood from the

heart to various organs of the body

(d) They have thick elastic walls without valves inside, blood flows under high pressure

and carries blood away from the heart to different parts of the body.

Ans: The answer is (d) They have thick elastic walls without valves inside, blood flows under high pressure and carries blood away from the heart to different parts of the body.

22. The filtration units of kidneys are called

(a) ureter

(b) urethra

(c) neurons

(d) nephrons

Ans: The answer is (d) nephrons

Explanation: The nephron is called the functional unit of the kidney. It helps in removing the waste products and excess substances from our bodies.

23. Oxygen liberated during photosynthesis comes from

(a) water

(b) chlorophyll

(c) carbon dioxide

(d) glucose

Ans: The answer is (a) water

Explanation: During photosynthesis, water molecules split to produce Oxygen and Hydrogen Ions. Oxygen is expelled out of plants and Hydrogen is used to reduce Carbon dioxide to produce carbohydrates.

24. The blood leaving the tissues becomes richer in

(a) carbon dioxide

(b) water

(c) haemoglobin

(d) oxygen

Ans: The answer is (a) carbon dioxide

Explanation: Because of respiration Carbon-di-oxide gets accumulated in tissues. Hence blood leaving the tissues becomes richer in Carbon-di-oxide.

25. Which of the following is an incorrect statement?

(a) Organisms grow with time

(b) Organisms must repair and maintain their structure

(c) Movement of molecules does not take place among cells

(d) Energy is essential for life processes

Ans: The answer is (c) Movement of molecules does not take place among cells

Explanation: The movement of molecule is a vital process. Movement of molecules in cells take place in active and passive modes such as Diffusion, osmosis, facilitated diffusion etc.

26. The internal (cellular) energy reserve in autotrophs is

(a) glycogen

(b) protein

(c) starch

(d) fatty acid

Ans: The answer is (c) starch

Explanation: Glycogen is the stored energy in animals, Plants store energy in the form of Starch.

27. Which of the following equations is the summary of photosynthesis?

(a) 6CO2 + 12H2O → C6H12O6 + 6O2 + 6H2O

(b) 6CO2 +H2O + Sunlight→C6H12O6 + O2 + 6H2O

(c) 6CO2 + 12H2O + Chlorophyll + Sunlight→ C6H12O6 + 6O2 + 6H2O

(d) 6CO2 + 12H2O + Chlorophyll + Sunlight→ C6H12O6 + 6CO2 + 6H2O

Ans: Answer is (c) 6CO2 + 12H2O + Chlorophyll + Sunlight→ C6H12O6 + 6O2 + 6H2O

Option a does not show the factors responsible for photosynthesis . Option b) is not a balanced equation. Option d) is wrong as it has CO2 in the products.

28. Choose the event that does not occur in photosynthesis

(a) Absorption of light energy by chlorophyll

(b) Reduction of carbon dioxide to carbohydrates

(c) Oxidation of carbon to carbon dioxide

(d) Conversion of light energy to chemical energy

Ans: Answer is (c) Oxidation of carbon to carbon dioxide.

Oxygen is released into the atmosphere by water molecules. Carbon does not oxidise into carbon dioxide. The energy of light is converted into chemical energy.

29. The opening and closing of the stomatal pore depends upon

(a) oxygen

(b) temperature

(c) water in guard cells

(d) concentration of CO2 in stomata

Ans: The answer is (c) water in guard cells

Explanation: The injection of water into guard cells facilitates guard cell opening. As a result, the guard cell becomes turgid. Water seeping from guard cells assists in guard cell closure. As a result, the guard cells will become flaccid.

30. Choose the forms in which most plants absorb nitrogen

(i) Proteins

(ii) Nitrates and Nitrites

(iii) Urea

(iv) Atmospheric nitrogen

(a) (i) and (ii)

(b) (ii) and (iii)

(c) (iii) and (iv)

(d) (i) and (iv)

Ans: The answer is (b) (ii) and (iii)

Explanation: Plants cannot absorb atmospheric Nitrogen. They can absorb the Nitrogen in the form of Nitrates, Nitrites and Urea present in the soil.

31. Which is the first enzyme to mix with food in the digestive tract?

(a) Pepsin

(b) Cellulase

(c) Amylase

(d) Trypsin

Ans: Answer is (c) Amylase

Amylase is a digestive enzyme that operates on starch to break it down into smaller molecules. As a result, Amylase is the first enzyme in the digestive system to interact with food.

32. Which of the following statement(s) is (are) correct?

(i) Pyruvate can be converted into ethanol and carbon dioxide by yeast

(ii) Fermentation takes place in aerobic bacteria

(iii) Fermentation takes place in mitochondria

(iv) Fermentation is a form of anaerobic respiration

(a) (i) and (iii)

(b) (ii) and (iv)

(c) (i) and (iv)

(d) (ii) and (iii)

Ans: The answer is(c) (i) and (iv)

Explanation: Fermentation is carried out by anaerobes in the cytoplasm. Hence option ii) and iii) are wrong.

33. Lack of oxygen in muscles often leads to cramps among cricketers. This results due to

(a) conversion of pyruvate to ethanol

(b) conversion of pyruvate to glucose

(c) non-conversion of glucose to pyruvate

(d) conversion of pyruvate to lactic acid

Ans: The answer is (d) conversion of pyruvate to lactic acid

Explanation: Breakdown of Pyruvate in the presence of oxygen takes place in mitochondria leading to the formation of Lactic acid. Due to workout oxygen is used for the production of energy leading to the lack of oxygen and production of lactic acid.

34. Choose the correct path of urine in our body

(a) kidney → ureter → urethra → urinary bladder

(b) kidney → urinary bladder → urethra → ureter

(c) kidney → ureters → urinary bladder → urethra

(d) urinary bladder → kidney → ureter → urethra

Ans: Answer is (c) kidney → ureters → urinary bladder → urethra

Explanation: Urine from the nephron is transported to the kidneys' collecting duct, where it enters the ureters. Each kidney has two ureters, which open into the urine bladder. The urinary bladder holds pee, and as the volume of urine collected rises, so does the size of the bladder. The bladder muscles contract and the bladder sphincter relaxes when the CNS sends a voluntary message, excreting pee through the urethra.

35. During deficiency of oxygen in tissues of human beings, pyruvic acid is converted

into lactic acid in the

(a) cytoplasm

(b) chloroplast

(c) mitochondria

(d) Golgi body

Ans: Answer is (a) cytoplasm

Explanation: When there is a deficiency in oxygen Pyruvate is broken down in the cytoplasm of muscle cells, resulting in the creation of lactic acid.

Short Answer Questions

36. Name the following

(a) The process in plants that links light energy with chemical energy

Ans: Photosynthesis is the conversion of light energy into chemical energy by plants and other creatures, which is subsequently released to fuel the organism's activities through cellular respiration.

(b) Organisms that can prepare their own food

Ans: An autotroph is a living organism that can feed itself by consuming light, water, carbon dioxide, or other things. Autotrophs are also known as producers since they manufacture their own food.

(c) The cell organelle where photosynthesis occurs

Ans: Chloroplasts are plant cell organelles that use the photosynthetic process to transform light energy into relatively stable chemical energy.

(d) Cells that surround a stomatal pore

Ans: Guard cells are found in the leaf epidermis and are bordered by stomatal holes.

(e) Organisms that cannot prepare their own food

Ans: A heterotroph is an organism that cannot make its own food and must rely on other organic carbon sources, mostly plant or animal materials, for nourishment.

(f) An enzyme secreted from gastric glands in the stomach that acts on proteins.

Ans: Pepsin is a stomach enzyme that aids in the digestion of proteins in diet. Pepsin is secreted by gastric main cells as pepsinogen, an inactive zymogen.

37. “All plants give out oxygen during the day and carbon dioxide during the night”. Do you agree with this statement? Give a reason.

Ans: The statement is incorrect since plants respire and expel carbon dioxide at all times,but they only give out oxygen during the day because photosynthesis can only occur in the presence of sunlight.

38. How do the guard cells regulate opening and closing of stomatal pores?

Ans: The introduction of water into guard cells aids in the opening of guard cells. The guard cell becomes turgid as a result of this. Water leaking from guard cells aids in the closing of guard cells. The guard cells will become flaccid as a result of this.

When water is introduced into guard cells, the cell becomes turgid, allowing the stomata to open. When water escapes from guard cells, the cell becomes flaccid, which causes the stomata to close.

39. 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.

Ans: As plants emit CO2 during breathing, plants kept under constant light survive longer. In the case of plants maintained in the dark, CO2 causes a shortage of oxygen, causing the plant to die sooner.

40. If a plant is releasing carbon dioxide and taking in oxygen during the day, does it mean that there is no photosynthesis occurring? Justify your answer.

Ans: If a plant is releasing carbon dioxide and taking in oxygen during the day means the plant is respiring; it does not mean that there is no photosynthesis occurring in the plant. This is because Photosynthesis and respiration are two independent processes.

41. Why do fishes die when taken out of water?

Ans: Fishes can respire only by using dissolved oxygen. When we take fish out of the water it cannot respire due to lack of dissolved oxygen and they die.

42. Differentiate between an autotroph and a heterotroph

Ans: The difference between autotrophs and heterotrophs is given below:

43. Is ‘nutrition’ a necessity for an organism? Discuss.

Ans: Nutrition is essential for organisms since it supplies the energy needed to carry out metabolic functions.

44. What would happen if green plants disappeared from earth?

Ans: Green plants are the sources of energy for all the heterotrophs on earth. Plants convert solar and chemical energy into viable food sources. If plants disappear from the earth it leads to an imbalance in the ecosystem and heterotrophs may die without food.

45. Leaves of a healthy potted plant were coated with vaseline. Will this plant remain healthy for long? Give reasons for your answer.

Ans:Coating vaseline to the leaves of a healthy plant will close its stomata pores and stop the respiration of plants and the plants die.

46. How does aerobic respiration differ from anaerobic respiration?

Ans: The difference between aerobic and anaerobic respiration are-

47. Match the words of Column (A) with that of Column (B)

Ans: 

48. Differentiate between an artery and a vein.

Ans:

49. What are the adaptations of leaves for photosynthesis?

Ans: Adaptation of leaf for photosynthesis are as follows

(a) The surface of the leaf is flat to allow greater exposure of light.

(b) Presence of chlorophyll to trap sunlight

(c) Presence of stomata on the lower surface for easy transpiration

50. Why is the small intestine in herbivores longer than in carnivores?

Ans: Food of herbivores contains mostly cellulose. To digest cellulose herbivores need help from certain bacteria. To accommodate the microbes and to facilitate digestion of food herbivores have a longer small intestine than carnivores.

51. What will happen if the mucus is not secreted by the gastric glands?

Ans: The inner lining of the stomach is protected by mucus against HCL. The inside lining of the stomach is kept moist by mucus. Mucus aids in the smooth passage of food particles through the digestive tract. Food will not easily pass through the digestive system if mucus is not produced. The stomach lining will be damaged by HCL, and the digestive process will be disrupted.

52. What is the significance of the emulsification of fats?

Ans: Emulsification is a process of breakage of larger fats molecules into digestible fat globules. Emulsification aids action enzymes on fats by breaking large fat molecules.

53. What causes movement of food inside the alimentary canal?

Ans: Peristalsis is the process that causes movement of food inside the alimentary canal.

54. Why does the absorption of digested food occur mainly in the small intestine?

Ans: Small intestines have specialized structures that facilitate the absorption of digested food. Small intestine has several folds that increase the area of absorption. Small intestine also has fingerlike projections called microvilli which are richly supplied by blood vessels.

55. Match Group (A) with Group (B)

Ans: 

56. Why is the rate of breathing in aquatic organisms much faster than in terrestrial organisms?

Ans: Aquatic species breathe more quicker than terrestrial organisms because oxygen supply in water is lower than on land, hence aquatic organisms must work harder to collect the oxygen they require.

57. Why is blood circulation in the human heart called double circulation?

Ans: In Humans blood flows in two directions simultaneously in one cardiac cycle. Oxygenated blood comes to the heart from the lungs and at the same time, deoxygenated blood goes from Heart towards the lungs. Because of this double movement is blood circulation in the human heart called double circulation.

58. What is the advantage of having a four-chambered heart?

Ans: Four chambered heart has the following advantages

(a) Clear cut division of labours among different chambers

(b) Segregation of oxygenated and deoxygenated blood in the heart.

(c) Efficiency of the heart will increase.

59. Mention the major events during photosynthesis

Ans: Major events of Photosynthesis are

(a) Absorption of light energy by chlorophyll

(b) Conversion of light energy into chemical energy

(c) Splitting of water molecules into Hydrogen and Oxygen

(d) Reduction of CO2 to form carbohydrates.

60. In each of the following situations what happens to the rate of photosynthesis?

(a) Cloudy days

Ans: Rate of photosynthesis will reduce due to the availability of sunlight.

(b) No rainfall in the area

Ans: Rainfall will not affect the rate of Photosynthesis

(c) Good manuring in the area

Ans: Manuring will not affect the rate of Photosynthesis

(d) Stomata get blocked due to dust

Ans: Blockage of stomata will reduce the rate of photosynthesis because blockage will affect availability of Carbon-di-oxide.

61. Name the energy currency in the living organisms. When and where is it produced?

Ans: Adenosine triphosphate (ATP) is the energy currency in living organisms. It is produced in Mitochondria during respiration.

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

Ans: These all are parasites. They live on or inside another body to obtain food from the host. In obtaining food, parasites always harm their host.

63. Explain the role of the mouth in digestion of food.

Ans: Role of mouth in digestion of food.

(i) Ingestion of food

(ii) Breakage of food by Mastication

(iii) Saliva aids easy swallowing of food

(iv) Salivary amylase breaks starch into simpler carbohydrates.

64.What are the functions of gastric glands present in the wall of the stomach?

Ans: Hydrochloric acid, pepsin and mucus are secreted by gastric glands present in the stomach. They have the following functions.

(i) HCL Kills germs present in the food and it decreases the PH of the stomach which is essential for the working of digestive enzymes.

(ii) Pepsin digests protein.

(iii) Mucus protects the stomach’s inner line from HCL.

65. Match the terms in Column (A) with those in Column (B)                         

Ans:

66. Name the correct substrates for the following enzymes

(a) Trypsin- The correct substrate for Trypsin is Protein.

(b) Amylase- The correct substrate for Amylase is Starch

(c) Pepsin- The correct substrate for Pepsin is Protein.

(d) Lipase- The correct substrate for Lipase is Lipids

67. Why do veins have thin walls as compared to arteries?

Ans: Vein walls are thin because blood flow through them does not impose pressure on them. The enormous pressure exerted on artery walls by blood flow necessitates thick walls.

68. What would happen if platelets were absent in the blood?

Ans: Platelets cause blood to clot. Blood will not clot if platelets are missing. Blood flow cannot be halted without clotting in the event of an injury, and this can be deadly.

69. Plants have low energy needs as compared to animals. Explain.

Ans: The majority of plant mobility happens by passive transport, which does not need energy, and plants remain stationary in one location rather than travelling in search of nourishment. In comparison to mammals, plants use less energy.

70. Why and how does water enter continuously into the root xylem?

Ans: Water should enter the root xylem continuously to assist the various processes such as photosynthesis. Continuous flow of water into root xylem is due to transpiration pull.

71. Why is transpiration important for plants?

Ans: Transpiration is important for plants because of the following reasons.

(a) It creates transpiration pull to facilitate the ascent of sap.

(b) Ascent of sap is necessary to make water available for photosynthesis.

(c) It helps a plant to get rid of excess water.

72. How do leaves of plants help in excretion?

Ans: Leaves play an important role in excretion in plants because CO2 is expelled out through pores of stomata present in the leaf. Plants shed leaves to get rid of excretory products deposited on them.

Long Answer Questions

73. Explain the process of nutrition in Amoeba.

Ans: Amoeba shows holozoic nutrition which comprises Ingestion, Digestion, Absorption, Assimilation and Egestion.

Ingestion:

Amoeba traps food particles through fingerlike projections called pseudopodia. Pseudopodia present outside its body and helps in taking food along with water

Digestion:

Food vacuoles are made after ingesting the food. Enzymes are released in the food vacuole for digestion.

Absorption:

After digestion, nutrients enter the cytoplasm through osmosis.

Assimilation:

Nutrients are utilized by the cell for various purposes.

Egestion:

Food vacuole goes near the cell membrane to empty its contents outside the cell. This results in the expulsion of waste materials from the cell.

74. Describe the alimentary canal of man.

Ans: Human Alimentary canal has the following parts

Buccal Cavity:

Generally called a mouth and it consists of tongue, teeth and salivary gland. It is the entry site for the food to the digestive system. Food is broken down into simpler molecules by mastication in the buccal cavity and salivary amylase breaks Starch into simpler carbohydrates in the Buccal cavity.

Oesophagus:

Buccal cavity is connected to the long tube-like structure called Oesophagus. Oesophagus connects the buccal cavity to the stomach and assists the inflow of food towards the stomach. Oesophagus has a valve to prevent backflow of food particles.

Stomach:

Stomach is a J Shaped organ which has gastric glands in it. Gastric glands secrets Hydrochloric acid, Pepsin and Mucus that helps in the digestion of food.

Small Intestine:

The small intestine is a lengthy, tightly coiled structure. The small intestine is responsible for a large portion of food absorption. Specialized features in the small intestine aid in the absorption of digested food. The folds in the small intestine improve the absorption area. The small intestine also features microvilli, which are fingerlike projections that are well-supplied by blood vessels.

Large Intestine :

This is shorter than the small intestine and its lumen is larger than that of the Small intestine. The major function of the large intestine is to absorb water from the remaining indigestible food matter and transmit the useless waste material from the body.

Rectum:

Large Intestine opens into rectum. Waste materials and undigested food are stored in the rectum.

Anus:

It is the opening at the end of the alimentary canal. Solid waste materials leave the body through Anus.

75. Explain the process of breathing in man

Ans: Breathing in Humans has two processes 1) Inhalation 2) Exhalation

Inhalation:

Inhalation is the process of taking oxygen. During this process, ribs come out and the diaphragm moves down. This increases the volume of the lungs and decreases the pressure. This will make the air move towards the lungs.

Exhalation:

Exhalation is a process of throwing out carbon-dioxide. During this process, ribs go down and the diaphragm moves up. This decreases the volume of the lungs and increases the pressure. As a result, air moves out of the lungs.

76. Explain the importance of soil for plant growth.

Ans: Soil is very important for the growth of the plant for the following reasons.

(i) Soil provides the base for the growth of the plants and provides a platform for the penetration of roots.

(ii) It acts as a reservoir of the water.

(iii) Soil has different minerals essential for the growth of the plant. Soil is the only medium from which soil obtains nutrients.

(iv) Soil has organic materials essential for the growth of the plants.

(v) Soil has microorganisms that have a symbiotic relationship with the plant and these microbes assist the plant in their growth and life processes.

77. Draw the diagram of the alimentary canal of man and label the following parts. Mouth, Oesophagus, Stomach, Intestine

Ans: The diagram of the alimentary canal is given below-

78. How do carbohydrates, proteins and fats get digested in human beings?

Ans: Carbohydrate Digestion

Digestion of carbohydrates starts with buccal cavity where salivary enzymes break down the starch into simple sugar molecules. Other sugar molecules break down to glucose in the small intestine.

Protein digestion

Proteins are partially digested by pepsin secreted by gastric glands present in the stomach. Then Pancreatic juice secrets trypsin and chymotrypsin enzymes in the small intestine where complete digestion of proteins takes place.

Fat Digestion

Fats are digested in the small intestine. Bile juice present in the liver emulsifies the fat which breaks fats into small globules. These small fat globules are converted into glycerol and fatty acids by Lipase enzyme.

79. Explain the mechanism of photosynthesis

Ans: Photosynthesis is a process by which plants produce their own food by utilizing sunlight, CO2 and water. CO2 and water are converted to carbohydrates with the evolution of oxygen. Photosynthesis reaction can be given by the following reaction.

6CO2 + 6H2O Sunlight energy C6H12O6 + 6O2

Process of Photosynthesis is divided into 4 processes

(i) Absorption of light energy by chlorophyll

(ii) Conversion of light energy into chemical energy

(iii) Splitting of water molecules into Hydrogen and Oxygen

(iv) Reduction of CO2 to produce carbohydrates

80. Explain the three pathways of breakdown in living organisms.

Ans: Glucose three pathways

Glucose is first broken down to 3 carbon molecules called pyruvate. This process takes place in the cytoplasm of all organisms. Pyruvate is further broken down by the flowing steps.

In yeast:

Pyruvate is broken down in the absence of oxygen and the process is called anaerobic respiration. In yeasts, pyruvate is broken down to produce CO2 and ethanol.

In Muscle Cells:

During rigorous physical activity, the energy demand of our muscle cells increases rapidly. This is compensated by anaerobic respiration in muscle cells. In muscle cells, pyruvate is broken down into lactic acid.

In Mitochondria:

In case of aerobic respiration( in presence of oxygen) pyruvate is broken down in mitochondria. Here Pyruvate is broken down to produce H2O and CO2. Aerobic respiration is most common in most organisms.

81. Describe the flow of blood through the heart of human beings

Ans: Flow of blood through heart

(a) Deoxygenated blood from different organs comes to the right atrium through the vena cava.

(b) From the right atrium, blood goes to the right ventricle. The tricuspid valve between the right atrium and right ventricle prevents the backflow of blood.

(c)From the right ventricle, blood goes to the lungs through the pulmonary artery. Inside the lungs, carbon dioxide is removed from the blood and oxygen enters the blood.

(d)From the lungs, blood goes to the left atrium through the pulmonary vein.

(e) From the left atrium, blood goes to the left ventricle.

(f) From the left ventricle, blood is pumped into the aorta so that it can be supplied to different organs.

82. Describe the process of urine formation in kidneys

Ans: Urine formation in kidneys: The basic filtration unit in the kidneys is a cluster of very thin-walled blood capillaries. Each capillary cluster in the kidney is associated with the cup-shaped end of a coiled tube called Bowman’s capsule that collects the filtrate . Each kidney has large numbers of these filtration units called nephrons packed close together.

Some substances in the initial filtrate, such as glucose, amino acids, salts and a major amount of water, are selectively reabsorbed as the urine flows along the tube. The amount of water re-absorbed depends on how much excess water is there in the body, and on how much dissolved waste there is to be excreted. The urine forming in each kidney eventually enters a long tube, the ureter, which connects the kidneys with the urinary bladder.

Urine is stored in the urinary bladder until the pressure of the expanded bladder leads to the urge to pass it out through the urethra. The bladder is muscular, so it is under nervous control.

NCERT Exemplar for Class 10 Science Chapter 6 - Life Processes

For understanding a chapter like life processes, which deals with the biology of humans, plants, and unicellular organisms, a Class 10 student needs to know each concept in detail. This can seem tricky but with the right practice from the right book, one can surely attain that. The students can practice NCERT and NCERT Exemplar because NCERT enhances their basics and the NCERT Exemplar asks more advanced questions based on the specific topic. Thus, a book like NCERT Exemplar helps each student to practice according to the needs of the Class 10 science board examination.

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