CBSE Class 10 Science Life processes Sure Shot Questions Set 01

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ASSIGNMENT QUESTIONS SET - 1
CHAPTER - 6
LIFE PROCESSES

1. Define nutrition? What are the different modes of nutrition? [2 Marks]

Answer:
1. Nutrition is the process of taking in food and its utilization by the body for growth, energy, repair, and other life processes.
2. The two main modes of nutrition are autotrophic nutrition and heterotrophic nutrition.

Teacher's Note:
a) Autotrophs synthesize their own food using inorganic substances.
b) Heterotrophs depend directly or indirectly on autotrophs for organic food.

2. What is the mode of nutrition in fungi? [1 Mark]

Answer:
1. Fungi exhibit saprotrophic nutrition.
2. They absorb nutrients from dead and decaying organic matter.

Teacher's Note:
a) Saprotrophs secrete digestive enzymes outside their body onto dead matter.

3. Name the pigment, which can absorb solar energy. [1 Mark]

Answer:
1. Chlorophyll is the primary pigment capable of absorbing solar energy.

Teacher's Note:
a) Chlorophyll traps light energy during the light reaction of photosynthesis.

4. Name the two stages in photosynthesis. [1 Mark]

Answer:
1. Light-dependent reaction (photochemical phase).
2. Light-independent reaction (biosynthetic phase or Calvin cycle).

Teacher's Note:
a) The light reaction occurs in thylakoids and the dark reaction in the stroma of chloroplasts.

5. Name the factors, which affect photosynthesis. [2 Marks]

Answer:
1. Light intensity, carbon dioxide concentration, and temperature.
2. Water availability and chlorophyll content.

Teacher's Note:
a) Mentioning at least four environmental and internal factors is essential for full marks.
b) Carbon dioxide concentration is often the limiting factor in natural conditions.

6. Define a herbivore and a carnivore. [2 Marks]

Answer:
1. Herbivores are primary consumers that feed directly on plants (e.g., cow, rabbit).
2. Carnivores are animals that feed on the flesh of other animals (e.g., lion, tiger).

Teacher's Note:
a) Herbivores occupy the second trophic level in a food chain.
b) Carnivores occupy the third or higher trophic levels.

7. What is compensation point? [1 Mark]

Answer:
1. It is the light intensity at which the rate of photosynthesis equals the rate of respiration in plants.

Answer:
1. Accessory pigments such as carotenoids (carotenes and xanthophylls).

Teacher's Note:
a) Accessory pigments absorb light of different wavelengths and transfer energy to chlorophyll a.

9. Where does digestion begin? [1 Mark]

Answer:
1. Digestion begins in the mouth (oral cavity) with the action of salivary amylase.

Teacher's Note:
a) Carbohydrate digestion starts here by breaking down starch into maltose.

10. What is the name given to the process of using the absorbed food for producing energy? [1 Mark]

Answer:
1. Assimilation and cellular respiration.

Teacher's Note:
a) Cellular respiration specifically breaks down absorbed food molecules to release usable energy in the form of ATP.

11. What happens to visible light of the Sun when it falls on chlorophyll? [1 Mark]

Answer:
1. It is absorbed by chlorophyll molecules, exciting electrons to a higher energy state.

Teacher's Note:
a) This absorbed solar energy drives the photolysis of water and ATP synthesis.

12. Name the product and by product of photosynthesis. [1 Mark]

Answer:
1. Main product is glucose (organic food) and the by-product is oxygen gas.

Teacher's Note:
a) Oxygen is released into the atmosphere as a result of the photolysis of water.

13. In which biochemical form the photosynthetic moves in phloem tissue? [1 Mark]

Answer:
1. In the form of sucrose.

Teacher's Note:
a) Sucrose is transported through sieve tubes using energy derived from ATP.

14. What are the raw materials of photosynthesis? [1 Mark]

Answer:
1. Carbon dioxide and water.

Teacher's Note:
a) Carbon dioxide is absorbed from the air and water is absorbed from the soil by roots.

15. What is the similarity between chlorophyll and hemoglobin? [2 Marks]

Answer:
1. Both are complex porphyrin-ring pigments containing a central metallic ion.
2. Both play essential roles in vital transport or energy capture processes in living organisms.

Teacher's Note:
a) Chlorophyll contains a magnesium ion while hemoglobin contains an iron ion.
b) Both show structural homology in their ring frameworks.

16. Name the products of photolysis of water. [1 Mark]

Answer:
1. Hydrogen ions, electrons, and oxygen gas.

Teacher's Note:
a) This reaction takes place in the presence of sunlight and specific enzymes in chloroplasts.

17. What are the end products of light dependant reaction? [1 Mark]

Answer:
1. ATP, NADPH, and oxygen.

Teacher's Note:
a) ATP and NADPH are utilized in the subsequent light-independent dark reaction.

18. Which cell organelle is the site of photosynthesis? [1 Mark]

Answer:
1. Chloroplast.

Teacher's Note:
a) Chloroplasts contain chlorophyll and specialized internal membrane systems.

19. What is the difference between digestion of heterotrophs and saprotrophs? [2 Marks]

Answer:
1. Heterotrophs ingest solid or liquid food first and then digest it internally inside a digestive cavity or tract.
2. Saprotrophs secrete digestive enzymes outside their bodies onto dead organic matter and absorb the predigested soluble nutrients.

Teacher's Note:
a) Internal digestion is characteristic of holozoic animals.
b) External extracellular digestion is characteristic of fungi and certain bacteria.

20. Give example of two plants and two animal parasites. [2 Marks]

Answer:
1. Plant parasites: Cuscuta (Dodder) and Viscum (Mistletoe).
2. Animal parasites: Tapeworm (Taenia) and Ascaris (Roundworm).

Teacher's Note:
a) Parasites derive nourishment directly from the living tissues of a host organism.
b) They inflict harm without necessarily killing the host immediately.

21. Name the enzyme present in saliva, what is its role in digestion? [2 Marks]

Answer:
1. Salivary amylase (ptyalin) is present in saliva.
2. Its role is to break down complex starch into simple sugars (maltose).

Teacher's Note:
a) It operates in a weakly acidic to neutral pH environment in the mouth.
b) Chemical digestion of food begins right here.

22. Which chemical is used to test for starch? Which colour shows the presence of starch? [2 Marks]

Answer:
1. Iodine solution is used to test for starch.
2. A blue-black colour indicates the presence of starch.

Teacher's Note:
a) Iodine forms a colored inclusion complex with the helical structure of amylose in starch.
b) Brownish-yellow iodine turning blue-black is a standard diagnostic test.

23. How does amoeba engulf its food? [2 Marks]

Answer:
1. Amoeba engulfs food using temporary finger-like extensions of its cell surface called pseudopodia.
2. The pseudopodia fuse around the food particle to form a food vacuole inside which digestion occurs.

Teacher's Note:
a) This process of ingestion is known as phagocytosis.
b) Digestive enzymes are secreted into the food vacuole to break down complex nutrients.

24. Name the parts of the digestive system of a grasshopper. [2 Marks]

Answer:
1. The alimentary canal consists of the foregut (mouth, pharynx, oesophagus, crop, gizzard), midgut (mesenteron with gastric caeca), and hindgut (ileum, colon, rectum).
2. Associated structures include salivary glands and Malpighian tubules (for excretion, connected near the midgut-hindgut junction).

Teacher's Note:
a) The gizzard helps in grinding food in insects.
b) Gastric caeca secrete digestive enzymes into the midgut.

25. What are the functions of the liver and the pancreas? [3 Marks]

Answer:
1. Liver functions: It secretes bile juice which helps in emulsification of fats and makes the food alkaline, and it stores excess glucose in the form of glycogen.
2. Pancreas functions: It secretes pancreatic juice containing digestive enzymes such as trypsin, lipase, and amylase.
3. The pancreatic enzymes help in the digestion of proteins, fats, and carbohydrates respectively in the small intestine.

Teacher's Note:
a) The liver and pancreas are important accessory glands of the digestive system.
b) Students often confuse the dual exocrine and endocrine nature of the pancreas.
c) Mentioning specific enzymes clearly fetches full marks in board examinations.

26. Define breathing. [1 Mark]

Answer:
Breathing is a physical process in which organisms take in oxygen rich air from the atmosphere and release carbon dioxide rich air out of the body.

Teacher's Note:
a) Breathing is purely a mechanical process involving inhalation and exhalation.
b) Distinguish breathing clearly from cellular respiration to avoid common errors.

27. How is respiration different from breathing? [3 Marks]

Answer:
1. Breathing is a physical process involving the intake of oxygen and release of carbon dioxide, whereas respiration is a biochemical process involving the oxidation of food to release energy.
2. Breathing takes place outside the cells in the respiratory organs, whereas respiration takes place inside the cells (cytoplasm and mitochondria).
3. No enzymes are involved in breathing, whereas various respiratory enzymes are required for cellular respiration.

Teacher's Note:
a) Presenting the answer in points or a comparative form makes it easy to evaluate.
b) Remember that breathing is just a part of the overall respiration process.
c) Emphasize that energy is released only during cellular respiration.

28. In which kind of respiration is more energy released? [1 Mark]

Answer:
More energy is released in aerobic respiration.

Teacher's Note:
a) Aerobic respiration involves the complete breakdown of glucose in the presence of oxygen.

29. Which part of the roots is involved in exchange of respiratory gases? [1 Mark]

Answer:
Root hairs are involved in the exchange of respiratory gases in roots.

Teacher's Note:
a) Oxygen diffuses into the root hair from the air spaces present between the soil particles.

30. What are (i) stomata and (ii) lenticels? [2 Marks]

Answer:
1. Stomata: These are tiny pores present on the epidermis of leaves that help in gaseous exchange and transpiration.
2. Lenticels: These are small porous tissues consisting of loosely packed cells found in the woody stems of plants for gaseous exchange.

Teacher's Note:
a) Both structures facilitate gaseous exchange in plants.
b) Stomata are found in green aerial parts, while lenticels are found in woody stems.

31. Give two points of differences between respiration in plants and respiration in animals. [2 Marks]

Answer:
1. In plants, gaseous exchange occurs through stomata and lenticels without any specialized respiratory organs, whereas most complex animals have specialized respiratory organs like gills or lungs.
2. The rate of respiration is generally slower in plants compared to animals.

Teacher's Note:
a) Focus on transport mechanisms and specialized structures.
b) Keep points concise and distinct.

32. Name the respiratory organs of
(i) fish
(ii) mosquito
(iii) earthworm
(iv) dog [2 Marks]

Answer:
(i) Fish - Gills
(ii) Mosquito - Trachea (Tracheal system)
(iii) Earthworm - Skin (Moist skin)
(iv) Dog - Lungs

Teacher's Note:
a) Match each organism directly with its correct respiratory surface.
b) Insects use air tubes called tracheae for breathing.

33. From where do the following take in oxygen? (i) prawn (ii) rat. [2 Marks]

Answer:
(i) Prawn takes in oxygen dissolved in water.
(ii) Rat takes in oxygen from the atmospheric air.

Teacher's Note:
a) Aquatic organisms utilize dissolved oxygen, while terrestrial organisms use atmospheric oxygen.
b) Ensure both parts are answered clearly in sequence.

34. State the function of epiglottis. [1 Mark]

Answer:
The function of the epiglottis is to prevent the entry of food particles into the windpipe (trarynx/larynx) during swallowing.

Teacher's Note:
a) It acts as a flap valve at the entrance of the trachea.

35. Define photolysis. [1 Mark]

Answer:
Photolysis is the splitting of water molecules into hydrogen ions and oxygen in the presence of light during the light-dependent reaction of photosynthesis.

Teacher's Note:
a) Mention the role of light energy and water splitting clearly.

36. What are the living organisms that cannot make their own food called? [1 Mark]

Answer:
They are called heterotrophs.

Teacher's Note:
a) Heterotrophs depend directly or indirectly on autotrophs for nutrition.

37. What are chemotrophs? [1 Mark]

Answer:
Chemotrophs are organisms that obtain energy by the oxidation of chemical electron donors in their environment rather than by using light.

Teacher's Note:
a) Common examples include certain bacteria found in deep sea vents.

38. Give the term- rhythmic contraction of alimentary canal muscle to propel food. [1 Mark]

Answer:
Peristalsis (or peristaltic movement).

Teacher's Note:
a) Spelling of peristalsis must be precise.

39. Name the three secretions of gastric glands. [1 Mark]

Answer:
The three secretions of gastric glands are hydrochloric acid, pepsin, and mucus.

Teacher's Note:
a) These components together form gastric juice inside the stomach.

40. What is the function of mucus in gastric gland? [1 Mark]

Answer:
Mucus protects the inner lining of the stomach from the corrosive action of hydrochloric acid.

Teacher's Note:
a) Lack of mucus leads to gastric ulcers due to acid action.

41. Name the sphincter which regulates the exit of food from the stomach. [1 Mark]

Answer:
Pyloric sphincter.

Teacher's Note:
a) Do not confuse with the cardiac sphincter which regulates entry into the stomach.

42. Give the functions of hydrochloric acid for the body. [2 Marks]

Answer:
1. It creates an acidic medium which activates the enzyme pepsin.
2. It kills harmful bacteria that enter the stomach along with food.

Teacher's Note:
a) HCl provides the optimal acidic pH required for gastric digestion.
b) Both functions carry equal weightage.

43. What is the role of pepsin in stomach? [1 Mark]

Answer:
Pepsin is a protein-digesting enzyme that breaks down proteins into smaller peptides in an acidic medium.

Teacher's Note:
a) Pepsin is secreted in an inactive form called pepsinogen to protect the stomach cells.

44. Why pancreas is called mixed gland? [1 Mark]

Answer:
Pancreas is called a mixed gland because it acts as both an exocrine gland (secreting digestive enzymes) and an endocrine gland (secreting hormones like insulin and glucagon).

Teacher's Note:
a) Mentioning both exocrine and endocrine functions is necessary for the mark.

45. Give two functions of bile juice, from which organ it is released? [2 Marks]

Answer:
1. It emulsifies large fat globules into smaller droplets to increase the efficiency of lipase enzyme action.
2. It makes the acidic food coming from the stomach alkaline so that pancreatic enzymes can act on it.
Bile juice is released from the liver (and stored in the gall bladder).

Teacher's Note:
a) Bile does not contain any digestive enzymes.
b) Clearly state both functions and the source organ.

46. Name the largest gland of our body. [1 Mark]

Answer:
Liver.

Teacher's Note:
a) The liver is the heaviest internal organ and largest gland in the human body.

47. Name any three important enzymes of pancreas and the food component on which they act. [3 Marks]

Answer:
1. Trypsin: Acts on proteins (peptones) to convert them into smaller peptides and amino acids.
2. Pancreatic lipase: Acts on emulsified fats to convert them into fatty acids and glycerol.
3. Pancreatic amylase: Acts on carbohydrates (starch) to convert them into simpler sugars (maltose).

Teacher's Note:
a) Ensure each enzyme is correctly paired with its specific substrate.
b) Providing the final product adds clarity.
c) Pancreatic juice works in the alkaline medium of the small intestine.

48. Where from intestinal juice come to the small intestine? [1 Mark]

Answer:
Intestinal juice is secreted by the glands present in the walls of the small intestine itself (crypts of Lieberkühn).

Teacher's Note:
a) It is also known as succus entericus.

49. What is the function of intestinal juice? [1 Mark]

Answer:
1. Intestinal juice contains enzymes that complete the digestion of carbohydrates into glucose, proteins into amino acids, and fats into fatty acids and glycerol.
2. It helps in the final conversion of complex food materials into their simplest absorbable forms.

Teacher's Note:
a) Intestinal juice is secreted by the walls of the small intestine.
b) It creates an alkaline medium required for enzymatic actions.

50. What are the simplest digestive product of carbohydrate, fats and protein? [1 Mark]

Answer:
1. The simplest digestive product of carbohydrates is glucose.
2. The simplest digestive products of fats are fatty acids and glycerol.
3. The simplest digestive product of proteins is amino acids.

Teacher's Note:
a) Complex food molecules cannot be absorbed directly by the blood.
b) Digestion breaks them down into these micromolecules for easy absorption across the intestinal wall.

51. Name the finger like projections of small intestine and what is the necessity of such type of projections in digestive system? [2 Marks]

Answer:
1. These projections are called villi.
2. They are necessary to increase the surface area for more efficient absorption of digested food.

Teacher's Note:
a) Villi ensure maximum absorption of nutrients into the bloodstream.
b) A larger surface area drastically speeds up the nutrient uptake process.

52. Why are intestinal villis highly vascular? [1 Mark]

Answer:
1. Intestinal villi are highly vascular to provide a rich supply of blood vessels.
2. This ensures rapid transport and absorption of digested food into the rest of the body.

Teacher's Note:
a) Blood vessels close to the epithelial lining shorten the diffusion pathway for nutrients.
b) Constant blood flow maintains a concentration gradient for nutrient absorption.

53. What is the function of anal sphincter? [1 Mark]

Answer:
1. The anal sphincter regulates the exit of solid waste (faeces) from the body.
2. It controls the release of waste materials through the anus.

Teacher's Note:
a) It is a ring of muscles controlling defecation.
b) It remains contracted until the reflex for elimination is initiated.

54. Name the site of anaerobic and aerobic respiration in a cell. [1 Mark]

Answer:
1. Anaerobic respiration takes place in the cytoplasm of a cell.
2. Aerobic respiration takes place in the mitochondria of a cell.

Teacher's Note:
a) Glycolysis is common to both and occurs in the cytoplasm.
b) The Krebs cycle and electron transport chain occur inside mitochondria.

55. A three carbon compound is the common product of both aerobic and anaerobic pathway. What is that? [1 Mark]

Answer:
1. The three-carbon compound is pyruvate or pyruvic acid.
2. It is formed during the breakdown of glucose in the cytoplasm.

Answer:
1. During vigorous exercise, muscle cells respire anaerobically due to a temporary lack of oxygen.
2. This leads to the accumulation of lactic acid in the muscles, causing painful cramps.

Teacher's Note:
a) Lactic acid buildup lowers the local pH inside muscle tissues.
b) Resting and taking deep breaths helps oxidize the accumulated lactic acid.

57. Distinguish between lactic acid and alcoholic fermentation? [2 Marks]

Answer:
1. Lactic acid fermentation produces lactic acid as a byproduct and occurs in animal muscle cells.
2. Alcoholic fermentation produces ethanol and carbon dioxide and occurs in yeast and plants.

Teacher's Note:
a) Both are forms of anaerobic respiration occurring without oxygen.
b) Different enzymes in different organisms dictate the final product.

58. Name the energy currency molecule of cell? [1 Mark]

Answer:
1. Adenosine triphosphate (ATP) is the energy currency of the cell.

Teacher's Note:
a) Energy released during respiration is stored in the form of ATP bonds.
b) ATP releases energy whenever required for cellular metabolic activities.

59. The breathing rate of aquatic animals is high, why? [2 Marks]

Answer:
1. Aquatic animals take in oxygen dissolved in water.
2. The amount of dissolved oxygen is fairly low compared to the amount of oxygen in the air, so aquatic animals must breathe faster to get enough oxygen.

Teacher's Note:
a) Water has much less dissolved oxygen than air.
b) Faster breathing and high gill ventilation rates compensate for this deficit.

60. What is the function of mucus and fine hair in nostrils? [2 Marks]

Answer:
1. Fine hair in the nostrils helps filter out dust particles and impurities from inhaled air.
2. Mucus moistens the air and traps remaining dust particles and germs.

Teacher's Note:
a) This mechanism prevents harmful particles from reaching the delicate lungs.
b) It acts as the primary defensive barrier in the respiratory system.

61. Give the function of network of capillaries on alveoli. [1 Mark]

Answer:
1. The capillary network around alveoli facilitates the exchange of oxygen and carbon dioxide between blood and air.

Teacher's Note:
a) Oxygen diffuses from alveoli into the blood.
b) Carbon dioxide diffuses from the blood into the alveoli to be exhaled.

62. Name the main carrier of oxygen and carbon dioxide in man. [1 Mark]

Answer:
1. Haemoglobin is the main carrier of oxygen.
2. Plasma is the main carrier of carbon dioxide (transported mostly in dissolved form).

Teacher's Note:
a) Haemoglobin has a very high affinity for oxygen.
b) Carbon dioxide is more soluble in water than oxygen, hence carried mostly by plasma.

63. Why does haemoglobin molecule act as efficient carrier of oxygen than diffusion process? [2 Marks]

Answer:
1. Diffusion alone is insufficient to deliver oxygen quickly to all parts of the human body due to our large multicellular size.
2. Haemoglobin binds strongly and rapidly with oxygen in the lungs and releases it efficiently where tissues need it.

Teacher's Note:
a) Diffusion is too slow for large organisms.
b) Pigments like haemoglobin increase oxygen-carrying capacity manifolds.

64. Give example of any three substances transported by plasma. [1 Mark]

Answer:
1. Carbon dioxide.
2. Dissolved food nutrients (such as glucose, amino acids).
3. Nitrogenous wastes (such as urea).

Teacher's Note:
a) Plasma is the fluid matrix of blood.
b) It also transports hormones and mineral ions.

65. Name the organ that- (a) pushes blood around body (b) make blood to reach to tissues. [2 Marks]

Answer:
(a) Heart
(b) Blood vessels (arteries and capillaries)

Teacher's Note:
a) The heart acts as a muscular pumping organ.
b) Blood vessels form the network of tubes distributing blood.

66. Name the blood vessel that carries blood from heart to lungs and from lungs to heart. [2 Marks]

Answer:
1. Pulmonary artery carries deoxygenated blood from the heart to the lungs.
2. Pulmonary vein carries oxygenated blood from the lungs back to the heart.

Teacher's Note:
a) Pulmonary blood vessels are exceptions to standard artery and vein definitions.
b) Arteries normally carry oxygenated blood, but the pulmonary artery carries deoxygenated blood.

67. How many heart chambers are there in (a) fish (b) frog (c) lizard (d) crocodile (e) birds (f) man? [3 Marks]

Answer:
(a) Fish: 2 chambers
(b) Frog: 3 chambers
(c) Lizard: 3 chambers (with an incompletely partitioned ventricle)
(d) Crocodile: 4 chambers
(e) Birds: 4 chambers
(f) Man: 4 chambers

Teacher's Note:
a) Higher vertebrate complexity corresponds to complete four-chambered separation.
b) Four chambers prevent mixing of oxygenated and deoxygenated blood, ensuring efficient energy supply.

68. Name the device that measures blood pressure. [1 Mark]

Answer:
1. Sphygmomanometer is the device used to measure blood pressure.

Teacher's Note:
a) It typically consists of an inflatable cuff and a pressure gauge.
b) It is usually wrapped around the upper arm.

69. What is the normal blood pressure of man? [1 Mark]

Answer:
1. The normal human blood pressure is 120 / 80 mmHg.

Teacher's Note:
a) 120 mmHg is the systolic pressure (ventricular contraction).
b) 80 mmHg is the diastolic pressure (ventricular relaxation).

70. Why capillaries are thin walled? [1 Mark]

Answer:
1. Capillaries are thin-walled to facilitate the easy exchange of materials (nutrients, gases, and wastes) between the blood and surrounding body cells.

Teacher's Note:
a) Their walls are only one cell thick.
b) This minimizes the diffusion distance for substances.

71. Which cell of blood help in wound healing? [1 Mark]

Answer:
1. Blood platelets help in blood clotting and wound healing.

Teacher's Note:
a) Platelets circulate in the blood and aggregate at injury sites.
b) They initiate the clotting cascade to prevent excessive blood loss.

72. What is the other name of lymph? [1 Mark]

Answer:
1. Lymph is also known as tissue fluid or extracellular fluid.

Teacher's Note:
a) It is similar to blood plasma but contains less protein.
b) It drains into the lymphatic system from intercellular spaces.

73. Give two function of lymph. [2 Marks]

Answer:
1. It carries digested and absorbed fat from the intestine.
2. It drains excess fluid from extracellular spaces back into the blood and helps the immune system by fighting infections.

Teacher's Note:
a) Lymph contains white blood cells (lymphocytes) for immunity.
b) It acts as a middleman between blood and tissues.

74. What is the direction of flow of water in xylem and food in phloem? [1 Mark]

Answer:
1. Water in xylem moves in an upward direction from roots to leaves.
2. Food in phloem can move in both upward and downward directions.

Teacher's Note:
a) Xylem transport is driven mainly by transpiration pull.
b) Phloem transport distributes synthesized sugars to storage organs and growing regions.

75. Why do plants need less energy than animals? [1 Mark]

Answer:
1. Plants are stationary and do not move from place to place.
2. A large proportion of plant body consists of dead cells, requiring less maintenance energy.

Teacher's Note:
a) Animals spend considerable energy on locomotion and searching for food.
b) Metabolic rate in plants is significantly lower than in warm-blooded animals.

76. Which process acts as suction to pull water from xylem cells of roots. [1 Mark]

Answer:
Transpiration.

Teacher's Note:
a) Loss of water through stomata creates a suction pressure.
b) This continuous pull draws water upward from the roots.

77. Mention two functions of transpiration. [1 Mark]

Answer:
1. It helps in the absorption and upward movement of water and dissolved minerals from roots to leaves.
2. It helps in temperature regulation of the plant.

Teacher's Note:
a) Transpiration creates the main driving force for water transport in tall trees.
b) Evaporative cooling prevents the plant from overheating in hot sunlight.

78. What are the two substances transported through phloem tissue? [1 Mark]

Answer:
1. Sucrose (or food/sugars).
2. Amino acids and other related organic molecules.

Teacher's Note:
a) Translocation occurs in sieve tubes with the help of companion cells.
b) Energy from ATP is utilized to actively transport substances into phloem.

79. Name the food component whose digestion produce nitrogenous waste? [1 Mark]

Answer:
Proteins.

Teacher's Note:
a) Proteins are composed of amino acids containing the amino group (NH₂).
b) Deamination of excess amino acids in the liver produces urea, a nitrogenous waste.

80. Which is the functional unit of kidney? [1 Mark]

Answer:
Nephron.

Teacher's Note:
a) Each human kidney contains over a million nephrons.
b) Nephrons filter blood, reabsorb useful substances, and secrete wastes to form urine.

81. What is the cup shaped structure of nephron called? [1 Mark]

Answer:
Bowman's capsule.

Teacher's Note:
a) It encloses a network of capillaries called the glomerulus.
b) Ultrafiltration of blood takes place across the walls of glomerulus and Bowman's capsule.

82. Which materials are selectively reabsorbed by nephron tubule? [1 Mark]

Answer:
Glucose, amino acids, salts, and a major portion of water.

Teacher's Note:
a) Reabsorption ensures essential nutrients are not lost in urine.
b) The extent of water reabsorbed depends on excess water in the body and dissolved wastes to be excreted.

83. What are the two important functions of kidney. [1 Mark]

Answer:
1. Removal of nitrogenous wastes like urea and uric acid from the blood.
2. Regulation of water and electrolyte balance (osmoregulation) in the body.

Teacher's Note:
a) Kidneys help maintain blood pressure and chemical homeostasis.
b) They filter the entire blood volume multiple times a day.

84. What is the other name of artificial kidney? [1 Mark]

Answer:
Dialysis machine.

Teacher's Note:
a) Used when both kidneys are damaged due to infection, injury, or restricted blood flow.
b) Works on the principle of dialysis using a semi-permeable dialysing fluid.

85. A key molecule NOT found in a chloroplast is... [1 Mark]
i. Chlorophyll
ii. Carbon dioxide
iii. Water
iv. Steroids

Answer: (iv) Steroids

1. Chloroplasts contain chlorophyll, and utilize carbon dioxide and water during photosynthesis.
2. Steroids are lipid-derived hormones not native structural components of chloroplasts.
3. Hence, the correct option is (iv).

Teacher's Note:
a) Chloroplasts are specialized organelles for photosynthesis.
b) They contain pigments, enzymes, and nucleic acids, but lack steroid molecules.

86. Photosynthesis is a good example of... [1 Mark]
i. Catabolism
ii. Anabolism

Answer: (ii) Anabolism

1. Anabolic pathways synthesize complex molecules from simpler ones.
2. Photosynthesis builds glucose from carbon dioxide and water, storing solar energy.
3. Hence, the correct option is (ii).

Teacher's Note:
a) Catabolic processes break down complex molecules to release energy.
b) Photosynthesis is an endothermic anabolic process.

87. Chloroplasts are found in heterotrophic cells. [1 Mark]
i. True
ii. False

Answer: (ii) False

1. Chloroplasts contain chlorophyll and perform photosynthesis, characteristic of autotrophic cells.
2. Heterotrophic cells lack chloroplasts as they depend on external organic food.
3. Hence, the correct option is (ii).

Teacher's Note:
a) Autotrophs manufacture their own food using light energy.
b) Animals and fungi are heterotrophs and do not possess chloroplasts.

88. Which of these choices is NOT in the structure of a chloroplast? [1 Mark]
i. Granum
ii. Stroma
iii. Cristae
iv. Thylakoid

Answer: (iii) Cristae

1. Cristae are folded inner membrane structures found inside mitochondria.
2. Granum, stroma, and thylakoids are parts of a chloroplast.
3. Hence, the correct option is (iii).

Teacher's Note:
a) Mitochondria contain cristae to increase surface area for cellular respiration.
b) Chloroplasts contain thylakoids stacked into grana suspended in a fluid stroma.

89. Only plants can conduct photosynthesis with chloroplasts. [1 Mark]
i. True
ii. False

Answer: (ii) False

1. Certain protists like algae and Euglena also contain chloroplasts and conduct photosynthesis.
2. Therefore, photosynthesis is not restricted exclusively to plants.
3. Hence, the correct option is (ii).

Teacher's Note:
a) Algae are photosynthetic organisms containing chloroplasts.
b) Some cyanobacteria also perform photosynthesis without membrane-bound chloroplasts.

90. Chloroplasts convert solar energy into physical energy. [1 Mark]
i. True
ii. False

Answer: (ii) False

1. Chloroplasts convert solar (light) energy into chemical energy, not physical energy.
2. The trapped light energy is stored in chemical bonds of glucose molecules.
3. Hence, the correct option is (ii).

Teacher's Note:
a) Energy transformations in living systems involve light to chemical energy conversion.
b) Chemical energy is subsequently used for various cellular activities.

91. What are nutrients? [1 Mark]

Answer:
Nutrients are substances required by living organisms for growth, energy, repair, and maintenance of life processes.

Teacher's Note:
a) Major nutrients include carbohydrates, proteins, fats, vitamins, and minerals.
b) They act as a source of energy and raw materials for body building.

92. Name the life process that provides energy. [1 Mark]

Answer:
Respiration.

Teacher's Note:
a) Cellular respiration breaks down digested food molecules to release energy in the form of ATP.
b) It occurs in all living cells continuously.

93. Which process provides all living things with raw materials for energy and growth? [1 Mark]

Answer:
1. Nutrition provides all living things with raw materials for energy and growth.

Teacher's Note:
a) Nutrition is the process of taking in food and utilizing it for energy and growth.
b) It is a vital life process common to all living organisms.

94. Name the essential pigment that absorbs light. [1 Mark]

Answer:
1. Chlorophyll is the essential pigment that absorbs light during photosynthesis.

Teacher's Note:
a) Chlorophyll is located in the chloroplasts of plant cells.
b) It traps solar energy to convert it into chemical energy.

95. Can you name the gaseous raw material of photosynthesis? [1 Mark]

Answer:
1. Carbon dioxide is the gaseous raw material of photosynthesis.

Teacher's Note:
a) Plants absorb carbon dioxide from the atmosphere through stomata.
b) It is reduced to carbohydrates in the presence of sunlight and chlorophyll.

96. If grana of a chloroplast are removed then, which of the reaction of will not be carried out? [1 Mark]

Answer:
1. Light-dependent reactions (or light reactions) will not be carried out.

Teacher's Note:
a) Grana are the sites of the light-dependent reaction of photosynthesis.
b) Stroma is responsible for the light-independent (dark) reaction.

97. Name the gas that is produced as a by-product during photosynthesis. [1 Mark]

Answer:
1. Oxygen is produced as a by-product during photosynthesis.

Teacher's Note:
a) Oxygen is released due to the photolysis of water.
b) It is expelled into the atmosphere through stomata.

98. Tick the correct statement. [1 Mark]
i. Arteries carry blood away from the heart while veins carry blood towards heart.
ii. Veins carry blood away from the heart while arteries carry blood towards heart.
iii. Both of them carry blood in the same direction.
iv. Either of them can carry blood away from the blood.

Answer: (i) Arteries carry blood away from the heart while veins carry blood towards heart.

1. Arteries distribute oxygenated blood from the heart to various body organs.
2. Veins collect deoxygenated blood from various organs and bring it back to the heart.
3. Hence, the correct option is (i).

Teacher's Note:
a) Arteries have thick, elastic walls to withstand high pressure.
b) Veins have valves to prevent the backward flow of blood.

99. Artificial removal of nitrogenous wastes from the human body in the event of kidney failure is [1 Mark]
i. Plasmolysis
ii. Dialysis
iii. Diffusion
iv. Osmosis

Answer: (ii) Dialysis

1. Dialysis is a medical procedure used to filter blood when kidneys fail to function.
2. It works on the principle of diffusion of solutes across a semi-permeable membrane.
3. Hence, the correct option is (ii).

Teacher's Note:
a) Patients with renal failure undergo hemodialysis periodically.
b) Nitrogenous wastes like urea are removed through this artificial process.

100. The function of salivary amylase is to convert [1 Mark]
i. Fats into fatty acids.
ii. Proteins into amino acids.
iii. Starch into sugar.
iv. Sugar into starch

Answer: (iii) Starch into sugar.

1. Salivary amylase is an enzyme present in human saliva.
2. It breaks down complex starch molecules into simpler sugars (maltose).
3. Hence, the correct option is (iii).

Teacher's Note:
a) Carbohydrate digestion begins right in the oral cavity.
b) Saliva helps in both lubrication and initial chemical digestion of food.