PHOTOSYNTHESIS HIGHER IN PLANTS 100 BEST MCQS.

PHOTOSYNTHESIS HIGHER IN PLANTS 100 BEST MCQS| NEET PRACTICE.

 

 

PHOTOSYNTHESIS HIGHER IN PLANTS

These questions cover various aspects of photosynthesis in higher plants and are designed to test the understanding of students in 11th grade. Each question is followed by its answer and a brief explanation or solution to aid in comprehension. Here are 100 multiple-choice questions.

 

1. What is the primary pigment involved in photosynthesis?
a) Chlorophyll a
b) Chlorophyll b
c) Carotenoids
d) Xanthophylls
*Answer: a) Chlorophyll a*
Solution: Chlorophyll a is the primary pigment responsible for capturing light energy during photosynthesis.

2. Where does photosynthesis primarily occur in higher plants?
a) Stomata
b) Chloroplasts
c) Xylem
d) Phloem
*Answer: b) Chloroplasts*
Solution: Photosynthesis primarily occurs within the chloroplasts of plant cells.

3. Which of the following is NOT a product of the light-dependent reactions of photosynthesis?
a) ATP
b) NADPH
c) Oxygen
d) Glucose
*Answer: d) Glucose*
Solution: Glucose is produced in the light-independent reactions (Calvin cycle), not in the light-dependent reactions.

4. In which part of the chloroplast do the light-dependent reactions take place?
a) Stroma
b) Thylakoid membrane
c) Granum
d) Inner membrane
*Answer: b) Thylakoid membrane*
Solution: The thylakoid membrane is where chlorophyll molecules are located and where light-dependent reactions occur.

5. Which molecule is split during the light-dependent reactions, resulting in the release of oxygen?
a) Water
b) Carbon dioxide
c) Glucose
d) ATP
*Answer: a) Water*
Solution: Water molecules are split during photolysis in the thylakoid membrane, releasing oxygen.

6. The Calvin cycle is also known as:
a) Light-dependent reactions
b) Carbon fixation
c) Photolysis
d) None of the above
*Answer: b) Carbon fixation*
Solution: The Calvin cycle is the stage of photosynthesis where carbon dioxide is converted into glucose.

7. Which enzyme is responsible for fixing carbon dioxide during the Calvin cycle?
a) Rubisco
b) ATP synthase
c) NADP reductase
d) Cytochrome c
*Answer: a) Rubisco*
Solution: Rubisco (Ribulose-1,5-bisphosphate carboxylase/oxygenase) is the enzyme that catalyzes the fixation of carbon dioxide during the Calvin cycle.

8. How many molecules of ATP and NADPH are required to fix one molecule of carbon dioxide during the Calvin cycle?
a) 1 ATP and 1 NADPH
b) 2 ATP and 2 NADPH
c) 3 ATP and 3 NADPH
d) 6 ATP and 6 NADPH
*Answer: c) 3 ATP and 3 NADPH*
Solution: The Calvin cycle requires 3 molecules of ATP and 3 molecules of NADPH to fix one molecule of carbon dioxide.

9. Which of the following is a by product of the Calvin cycle?
a) Oxygen
b) ATP
c) NADPH
d) Glucose
*Answer: d) Glucose*
Solution: Glucose is produced as a result of carbon fixation and reduction of CO2 during the Calvin cycle.

10. What is the primary function of the light-dependent reactions?
a) Production of glucose
b) Absorption of light energy
c) Fixation of carbon dioxide
d) Release of oxygen
*Answer: b) Absorption of light energy*
Solution: The primary function of the light-dependent reactions is to capture and convert light energy into chemical energy in the form of ATP and NADPH.

11. In photosynthesis, light energy is used to convert:
a) Carbon dioxide and water into glucose
b) Glucose and oxygen into carbon dioxide and water
c) Oxygen and water into carbon dioxide and glucose
d) Water and carbon dioxide into oxygen and ATP
*Answer: a) Carbon dioxide and water into glucose*
Solution: Light energy is used to convert carbon dioxide and water into glucose during photosynthesis.

12. Which of the following is NOT a factor that affects the rate of photosynthesis?
a) Light intensity
b) Carbon dioxide concentration
c) Temperature
d) pH of the soil
*Answer: d) pH of the soil*
Solution: While soil pH may affect nutrient availability for plants, it does not directly impact the rate of photosynthesis.

13. What happens to the rate of photosynthesis when the temperature becomes too high?
a) It increases
b) It decreases
c) It remains constant
d) It fluctuates randomly
*Answer: b) It decreases*
Solution: High temperatures can denature enzymes involved in photosynthesis, leading to a decrease in the rate of photosynthesis.

14. The oxygen released during photosynthesis comes from:
a) Carbon dioxide
b) Water
c) Glucose
d) Oxygen in the air
*Answer: b) Water*
Solution: Oxygen released during photosynthesis comes from the splitting of water molecules during the light-dependent reactions.

15. How does the stomata regulate gas exchange during photosynthesis?
a) By opening and closing to control the entry of light
b) By controlling the diffusion of oxygen and carbon dioxide
c) By releasing glucose into the atmosphere
d) By absorbing water from the soil
*Answer: b) By controlling the diffusion of oxygen and carbon dioxide*
Solution: Stomata open and close to regulate the exchange of gases, allowing carbon dioxide to enter and oxygen to exit the leaf.

16. What is the primary source of energy for photosynthesis?
a) Heat
b) Light
c) ATP
d) Glucose
*Answer: b) Light*
Solution: Light energy is absorbed by chlorophyll and used to power the process of photosynthesis.

17. During which phase of photosynthesis is oxygen produced?
a) Light-dependent reactions
b) Calvin cycle
c) Both a and b
d) None of the above
*Answer: a) Light-dependent reactions*
Solution: Oxygen is produced as a by product of the light-dependent reactions through the process of photolysis.

18. The Calvin cycle takes place in the:
a) Stroma
b) Thylakoid membrane
c) Granum
d) Outer membrane of chloroplast
*Answer: a) Stroma*
Solution: The Calvin cycle occurs in the stroma of the chloroplast.

19. What is the role of NADPH in photosynthesis?
a) Absorption of light energy
b) Fixation of carbon dioxide
c) Carrying high-energy electrons
d) Splitting of water molecules
*Answer: c) Carrying high-energy electrons*
Solution: NADPH carries high-energy electrons produced during the light-dependent reactions to the Calvin cycle

for carbon fixation.

20. Which of the following is a product of the light-dependent reactions that is used in the Calvin cycle?
a) ATP
b) NADPH
c) Oxygen
d) All of the above
*Answer: d) All of the above*
Solution: Both ATP and NADPH are products of the light-dependent reactions and are utilized in the Calvin cycle.

21. The first stable compound formed during the Calvin cycle is:
a) Glycerate 3-phosphate (GP)
b) Ribulose bisphosphate (RuBP)
c) 3-phosphoglycerate (3-PGA)
d) Glucose
*Answer: c) 3-phosphoglycerate (3-PGA)*
Solution: The first stable compound formed during the Calvin cycle is 3-phosphoglycerate (3-PGA) after carbon dioxide fixation.

22. Which of the following is NOT a phase of the Calvin cycle?
a) Carbon fixation
b) Reduction
c) Photorespiration
d) Regeneration of RuBP
*Answer: c) Photorespiration*
Solution: Photorespiration is a side reaction that occurs in plants when the concentration of carbon dioxide is low, it is not a phase of the Calvin cycle.

23. How many carbon dioxide molecules are required to produce one molecule of glucose during the Calvin cycle?
a) 3
b) 6
c) 9
d) 12
*Answer: b) 6*
Solution: Six molecules of carbon dioxide are required to produce one molecule of glucose during the Calvin cycle.

24. What is the purpose of the regeneration of RuBP in the Calvin cycle?
a) To release carbon dioxide
b) To replenish ATP
c) To regenerate the starting molecule for carbon fixation
d) To produce glucose
*Answer: c) To regenerate the starting molecule for carbon fixation*
Solution: Regeneration of RuBP ensures that the Calvin cycle can continue by providing the substrate necessary for carbon fixation.

25. Which of the following colors of light is least effective in driving photosynthesis?
a) Blue
b) Red
c) Green
d) Yellow
*Answer: c) Green*
Solution: Green light is least effective in driving photosynthesis because chlorophyll reflects green light and does not absorb it efficiently.

26. The light-independent reactions of photosynthesis are also known as:
a) Calvin cycle
b) Photophosphorylation
c) Photolysis
d) Carbon fixation
*Answer: a) Calvin cycle*
Solution: The light-independent reactions are often referred to as the Calvin cycle, named after Melvin Calvin who elucidated the pathway.

27. Which of the following is NOT a necessary condition for photosynthesis?
a) Carbon dioxide
b) Oxygen
c) Water
d) Light
*Answer: b) Oxygen*
Solution: While oxygen is produced as a by product of photosynthesis, it is not necessary for the process to occur.

28. What is the significance of the C4 pathway in photosynthesis?
a) It allows plants to conserve water in arid conditions
b) It increases the efficiency of carbon fixation in low light conditions
c) It reduces photorespiration in hot climates
d) It enables plants to produce glucose without light
*Answer: c) It reduces photorespiration in hot climates*
Solution: The C4 pathway reduces photorespiration and increases water-use efficiency in plants adapted to hot and dry environments.

29. Which of the following is a C4 plant?
a) Rice
b) Wheat
c) Sugarcane
d) All of the above
*Answer: d) All of the above*
Solution: Rice, wheat, and sugarcane are examples of C4 plants that utilize the C4 pathway for carbon fixation.

30. In CAM photosynthesis, carbon dioxide is primarily fixed during:
a) Daytime
b) Night time
c) Both daytime and night time
d) Neither daytime nor night time
*Answer: b) Night time*
Solution: CAM plants fix carbon dioxide primarily during the night time when stomata are open to minimize water loss.

31. The enzyme responsible for carbon fixation in C4 plants is:
a) Rubisco
b) PEP carboxylase
c) ATP synthase
d) NADP reductase
*Answer: b) PEP carboxylase*
Solution: PEP carboxylase is the enzyme responsible for carbon fixation in C4 plants, which has a higher affinity for carbon dioxide than rubisco.

32. Which of the following is NOT a characteristic of CAM plants?
a) They open their stomata during the day.
b) They fix carbon dioxide at night.
c) They are commonly found in arid environments.
d) They use the C3 pathway for carbon fixation.
*Answer: d) They use the C3 pathway for carbon fixation*
Solution: CAM plants use a modified pathway for carbon fixation known as Crassulacean Acid Metabolism (CAM), not the C3 pathway.

33. In which organelle does photosynthesis take place?
a) Mitochondria
b) Golgi apparatus
c) Chloroplast
d) Nucleus
*Answer: c) Chloroplast*
Solution: Photosynthesis occurs in the chloroplasts of plant cells.

34. What gas is consumed during photosynthesis?
a) Carbon dioxide
b) Oxygen
c) Nitrogen
d) Hydrogen
*Answer: a) Carbon dioxide*
Solution: Carbon dioxide is consumed during photosynthesis for the synthesis of glucose.

35. The energy currency used in photosynthesis is:
a) Glucose
b) ATP
c) NADPH
d) Water
*Answer: b) ATP*
Solution: ATP is the energy currency used in photosynthesis to drive various biochemical reactions.

36. What is the role of water in photosynthesis?
a) Water is a product of photosynthesis.
b) Water is a reactant in the light-dependent reactions.
c) Water provides structural support to the plant.
d) Water is necessary for respiration.
*Answer: b) Water is a reactant in the light-dependent reactions*
Solution: Water molecules are split during the light-dependent reactions to provide electrons and protons for the production of ATP and NADPH.

37. During photosynthesis, oxygen is produced as a by product of:
a) Carbon fixation
b) Photophosphorylation
c) Photolysis
d) Calvin cycle
*Answer: c) Photolysis*
Solution: Oxygen is produced as a by product of the photolysis of water during the light-dependent reactions.

38. What is the fate of the oxygen produced during photosynthesis?
a) It is used in respiration by the plant.
b) It is released into the atmosphere.
c) It is converted into glucose.
d) It is stored in the

chloroplast.
*Answer: b) It is released into the atmosphere*
Solution: The oxygen produced during photosynthesis is released into the atmosphere as a by product.

39. The source of carbon for photosynthesis is:
a) Carbon dioxide
b) Oxygen
c) Glucose
d) Water
*Answer: a) Carbon dioxide*
Solution: Carbon dioxide is the source of carbon used by plants during photosynthesis for the synthesis of organic molecules.

40. What is the significance of photosynthesis for the ecosystem?
a) It releases oxygen necessary for respiration.
b) It provides food for heterotrophs.
c) It reduces the concentration of carbon dioxide in the atmosphere.
d) All of the above
*Answer: d) All of the above*
Solution: Photosynthesis plays a crucial role in the ecosystem by producing oxygen, providing food, and regulating atmospheric carbon dioxide levels.

41. Which of the following is a product of the light-dependent reactions that is used in the Calvin cycle?
a) ATP
b) NADPH
c) Oxygen
d) All of the above
*Answer: d) All of the above*
Solution: Both ATP and NADPH are produced during the light-dependent reactions and are utilized in the Calvin cycle.

42. The primary electron acceptor in the light-dependent reactions is:
a) Chlorophyll
b) Water
c) NADP+
d) NADPH
*Answer: c) NADP+*
Solution: NADP+ is reduced to NADPH by accepting electrons during the light-dependent reactions.

43. The light-dependent reactions occur in the:
a) Thylakoid membrane
b) Stroma
c) Outer membrane of chloroplast
d) Granum
*Answer: a) Thylakoid membrane*
Solution: The light-dependent reactions take place in the thylakoid membrane of the chloroplast.

44. What is the role of chlorophyll in photosynthesis?
a) Absorption of light energy
b) Fixation of carbon dioxide
c) Production of ATP
d) Release of oxygen
*Answer: a) Absorption of light energy*
Solution: Chlorophyll absorbs light energy during photosynthesis, which is then converted into chemical energy.

45. The process of converting light energy into chemical energy is known as:
a) Respiration
b) Photosynthesis
c) Fermentation
d) Glycolysis
*Answer: b) Photosynthesis*
Solution: Photosynthesis is the process by which light energy is converted into chemical energy in the form of glucose.

46. Which of the following is a waste product of photosynthesis?
a) Glucose
b) Oxygen
c) Carbon dioxide
d) Water
*Answer: c) Carbon dioxide*
Solution: Carbon dioxide is released as a waste product of photosynthesis.

47. The source of electrons for the light-dependent reactions is:
a) Carbon dioxide
b) Oxygen
c) Water
d) Glucose
*Answer: c) Water*
Solution: Water molecules are split during the light-dependent reactions to provide electrons for the photosynthetic electron transport chain.

48. The enzyme responsible for the synthesis of ATP during the light-dependent reactions is:
a) Rubisco
b) ATP synthase
c) NADP reductase
d) PEP carboxylase
*Answer: b) ATP synthase*
Solution: ATP synthase is the enzyme responsible for synthesizing ATP from ADP and inorganic phosphate during photophosphorylation.

49. The light-independent reactions of photosynthesis occur in the:
a) Stroma
b) Thylakoid membrane
c) Granum
d) Outer membrane of chloroplast
*Answer: a) Stroma*
Solution: The light-independent reactions (Calvin cycle) occur in the stroma of the chloroplast.

50. The purpose of the Calvin cycle is to:
a) Produce ATP
b) Fix carbon dioxide
c) Produce oxygen
d) Split water molecules
*Answer: b) Fix carbon dioxide*
Solution: The Calvin cycle fixes carbon dioxide into organic molecules, ultimately producing glucose.

51. The regeneration of RuBP in the Calvin cycle requires:
a) ATP
b) NADPH
c) Carbon dioxide
d) Oxygen
*Answer: a) ATP*
Solution: Regeneration of RuBP in the Calvin cycle requires ATP to convert PGA back into RuBP.

52. The enzyme responsible for carbon fixation in the Calvin cycle is:
a) Rubisco
b) PEP carboxylase
c) ATP synthase
d) NADP reductase
*Answer: a) Rubisco*
Solution: Rubisco catalyzes the carboxylation of RuBP to initiate carbon fixation in the Calvin cycle.

53. The products of the Calvin cycle include:
a) ATP and NADPH
b) Glucose and oxygen
c) G3P and RuBP
d) PGA and ADP
*Answer: c) G3P and RuBP*
Solution: The Calvin cycle produces G3P (glyceraldehyde-3-phosphate) and regenerates RuBP (ribulose-1,5-bisphosphate) as its primary products.

54. The primary function of NADPH in photosynthesis is to:
a) Absorb light energy
b) Fix carbon dioxide
c) Carry high-energy electrons
d) Release oxygen
*Answer: c) Carry high-energy electrons*
Solution: NADPH carries high-energy electrons produced during the light-dependent reactions to the Calvin cycle for carbon fixation.

55. The first stable compound formed during the Calvin cycle is:
a) PGA
b) G3P
c) RuBP
d) ATP
*Answer: a) PGA*
Solution: The first stable compound formed during the Calvin cycle is 3-phosphoglycerate (PGA) after carbon dioxide fixation.

56. The final electron acceptor in the light-dependent reactions is:
a) Oxygen
b) NADP+
c) Carbon dioxide
d) Chlorophyll
*Answer: b) NADP+*
Solution: NADP+ is reduced to NADPH by accepting electrons from the electron transport chain during the light-dependent reactions.

57. Which of the following is a characteristic of C4 plants?
a) They have a high rate of photorespiration.
b) They are adapted to hot and dry environments.
c) They fix carbon dioxide directly into RuBP.
d) They have low water-use efficiency.
*Answer: b) They are adapted to hot and dry environments*
Solution: C4 plants have adaptations that reduce photorespiration and increase water-use efficiency, making them well-suited for hot and dry environments.

58. CAM plants open their stomata primarily during:
a) Daytime
b) Night time
c) Both daytime and night time
d) Neither daytime nor night time
*Answer: b) Night time*
Solution: CAM plants open their stomata primarily during the night time to minimize water loss while fixing carbon dioxide.

59. Which of the following statements about CAM plants is true?
a) They fix carbon dioxide directly into RuBP.
b) They have a low rate of photorespiration.
c) They perform photosynthesis only during the day.
d) They are commonly found in temperate climates.
*Answer: b) They have a low rate of photorespiration*
Solution: CAM plants have a low rate of photorespiration due to their unique carbon fixation pathway, which minimizes water loss.

60. Which of the following is a key difference between C3 and C4 plants?
a) The location of the Calvin cycle
b) The presence of chlorophyll
c) The type of stomata
d) The mechanism of carbon fixation
*Answer: d) The mechanism of carbon fixation*
Solution: C3 plants fix carbon dioxide directly into RuBP, while C4 plants initially fix carbon dioxide into a four-carbon compound.

61. In which organelle does the Calvin cycle take place?
a) Mitochondria
b) Chloroplast
c) Nucleus
d) Golgi apparatus
*Answer: b) Chloroplast*
Solution: The Calvin cycle takes place in the stroma of the chloroplast.

62. During photosynthesis, ATP is synthesized in the:
a) Light-dependent reactions
b) Calvin cycle
c) Both a and b
d) None of the above
*Answer: a) Light-dependent reactions*
Solution: ATP is synthesized during photophosphorylation, which occurs in the light-dependent reactions.

63. The enzyme responsible for the synthesis of ATP in photosynthesis is:
a) Rubisco
b) ATP synthase
c) NADP reductase
d) PEP carboxylase
*Answer: b) ATP synthase*
Solution: ATP synthase is the enzyme responsible for synthesizing ATP from ADP and inorganic phosphate during photophosphorylation.

64. In photosynthesis, carbon dioxide is reduced to glucose during:
a) The light-dependent reactions
b) The Calvin cycle
c) Photolysis
d) Photorespiration
*Answer: b) The Calvin cycle*
Solution: Carbon dioxide is reduced to glucose during the Calvin cycle, which is the light-independent phase of photosynthesis.

65. Which of the following is NOT a product of the light-dependent reactions?
a) Oxygen
b) ATP
c) NADPH
d) Glucose
*Answer: d) Glucose*
Solution: Glucose is not a product of the light-dependent reactions; it is produced during the Calvin cycle, which is the light-independent phase.

66. The primary function of the light-dependent reactions is to:
a) Produce oxygen
b) Fix carbon dioxide
c) Produce ATP and NADPH
d) Regenerate RuBP
*Answer: c) Produce ATP and NADPH*
Solution: The primary function of the light-dependent reactions is to produce ATP and NADPH, which are used in the Calvin cycle to fix carbon dioxide.

67. In photosynthesis, water is split into oxygen, protons, and electrons during:
a) Photophosphorylation
b) Carbon fixation
c) Photorespiration
d) Photolysis
*Answer: d) Photolysis*
Solution: Water is split into oxygen, protons, and electrons during photolysis in the light-dependent reactions.

68. The source of oxygen produced during photosynthesis is:
a) Carbon dioxide
b) Glucose
c) Water
d) ATP
*Answer: c) Water*
Solution: Oxygen produced during photosynthesis comes from the splitting of water molecules during the light-dependent reactions.

69. The light-independent reactions of photosynthesis are also known as:
a) Photophosphorylation
b) Carbon fixation
c) Photolysis
d) Photorespiration
*Answer: b) Carbon fixation*
Solution: The light-independent reactions involve the fixation of carbon dioxide into organic molecules and are often referred to as carbon fixation.

70. The enzyme responsible for fixing carbon dioxide during the Calvin cycle is:
a) Rubisco
b) ATP synthase
c) NADP reductase
d) PEP carboxylase
*Answer: a) Rubisco*
Solution: Rubisco is the enzyme responsible for catalyzing the fixation of carbon dioxide by attaching it to ribulose-1,5-bisphosphate (RuBP) during the Calvin cycle.

71. Which of the following is a by product of the light-independent reactions?
a) Oxygen
b) ATP
c) NADPH
d) Glucose
*Answer: d) Glucose*
Solution: Glucose is produced as a by product of the light-independent reactions (Calvin cycle) of photosynthesis.

72. The Calvin cycle takes place in the:
a) Thylakoid membrane
b) Stroma
c) Granum
d) Outer membrane of chloroplast
*Answer: b) Stroma*
Solution: The Calvin cycle occurs in the stroma of the chloroplast, where enzymes and substrates necessary for carbon fixation are present.

73. How many molecules of ATP and NADPH are required to fix one molecule of carbon dioxide during the Calvin cycle?
a) 1 ATP and 1 NADPH
b) 2 ATP and 2 NADPH
c) 3 ATP and 3 NADPH
d) 6 ATP and 6 NADPH
*Answer: c) 3 ATP and 3 NADPH*
Solution: Three molecules of ATP and three molecules of NADPH are required to fix one molecule of carbon dioxide during the Calvin cycle.

74. What is the primary function of the light-dependent reactions?
a) Production of glucose
b) Absorption of light energy
c) Fixation of carbon dioxide
d) Release of oxygen
*Answer: b) Absorption of light energy*
Solution: The primary function of the light-dependent reactions is to capture and convert light energy into chemical energy in the form of ATP and NADPH.

75. In photosynthesis, light energy is used to convert:
a) Carbon dioxide and water into glucose
b) Glucose and oxygen into carbon dioxide and water
c) Oxygen and water into carbon dioxide and glucose
d) Water and carbon dioxide into oxygen and ATP
*Answer: a) Carbon dioxide and water into glucose*
Solution: Light energy is used to convert carbon dioxide and water into glucose during photosynthesis.

76. Which of the following is NOT a factor that affects the rate of photosynthesis?
a) Light intensity
b) Carbon dioxide concentration
c) Temperature
d) pH of the soil
*Answer: d)pH of the soil*
Solution: While soil pH may affect nutrient availability for plants, it does not directly impact the rate of photosynthesis.

77. What happens to the rate of photosynthesis when the temperature becomes too high?
a) It increases
b) It decreases
c) It remains constant
d) It fluctuates randomly
*Answer: b) It decreases*
Solution: High temperatures can denature enzymes involved in photosynthesis, leading to a decrease in the rate of photosynthesis.

78. The oxygen released during photosynthesis comes from:
a) Carbon dioxide
b) Water
c) Glucose
d) Oxygen in the air
*Answer: b) Water*
Solution: Oxygen released during photosynthesis comes from the splitting of water molecules during the light-dependent reactions.

79. How does the stomata regulate gas exchange during photosynthesis?
a) By opening and closing to control the entry of light
b) By controlling the diffusion of oxygen and carbon dioxide
c) By releasing glucose into the atmosphere
d) By absorbing water from the soil
*Answer: b) By controlling the diffusion of oxygen and carbon dioxide*
Solution: Stomata open and close to regulate the exchange of gases, allowing carbon dioxide to enter and oxygen to exit the leaf.

80. What is the primary source of energy for photosynthesis?
a) Heat
b) Light
c) ATP
d) Glucose
*Answer: b) Light*
Solution: Light energy is absorbed by chlorophyll and used to power the process of photosynthesis.

81. During which phase of photosynthesis is oxygen produced?
a) Light-dependent reactions
b) Calvin cycle
c) Both a and b
d) None of the above
*Answer: a) Light-dependent reactions*
Solution: Oxygen is produced as a by product of the light-dependent reactions through the process of photolysis.

82. The Calvin cycle is also known as:
a) Light-dependent reactions
b) Carbon fixation
c) Photolysis
d) None of the above
*Answer: b) Carbon fixation*
Solution: The Calvin cycle is the stage of photosynthesis where carbon dioxide is converted into glucose.

83. Which enzyme is responsible for fixing carbon dioxide during the Calvin cycle?
a) Rubisco
b) ATP synthase
c) NADP reductase
d) Cytochrome c
*Answer: a) Rubisco*
Solution: Rubisco (Ribulose-1,5-bisphosphate carboxylase/oxygenase) is the enzyme that catalyzes the fixation of carbon dioxide during the Calvin cycle.

84. How many molecules of ATP and NADPH are required to fix one molecule of carbon dioxide during the Calvin cycle?
a) 1 ATP and 1 NADPH
b) 2 ATP and 2 NADPH
c) 3 ATP and 3 NADPH
d) 6 ATP and 6 NADPH
*Answer: c) 3 ATP and 3 NADPH*
Solution: The Calvin cycle requires 3 molecules of ATP and 3 molecules of NADPH to fix one molecule of carbon dioxide.

85. Which of the following is a by product of the Calvin cycle?
a) Oxygen
b) ATP
c) NADPH
d) Glucose
*Answer: d) Glucose*
Solution: Glucose is produced as a result of carbon fixation and reduction of CO2 during the Calvin cycle.

86. What is the primary function of the light-dependent reactions?
a) Production of glucose
b) Absorption of light energy
c) Fixation of carbon dioxide
d) Release of oxygen
*Answer: b) Absorption of light energy*
Solution: The primary function of the light-dependent reactions is to capture and convert light energy into chemical energy in the form of ATP and NADPH.

87. In photosynthesis, light energy is used to convert:
a) Carbon dioxide and water into glucose
b) Glucose and oxygen into carbon dioxide and water
c) Oxygen and water into carbon dioxide and glucose
d) Water and carbon dioxide into oxygen and ATP
*Answer: a) Carbon dioxide and water into glucose*
Solution: Light energy is used to convert carbon dioxide and water into glucose during photosynthesis.

88. Which of the following is NOT a factor that affects the rate of photosynthesis?
a) Light intensity
b) Carbon dioxide concentration
c) Temperature
d) pH of the soil
*Answer: d) pH of the soil*
Solution: While soil pH may affect nutrient availability for plants, it does not directly impact the rate of photosynthesis.

89. What happens to the rate of photosynthesis when the temperature becomes too high?
a) It increases
b) It decreases
c) It remains constant
d) It fluctuates randomly
*Answer: b) It decreases*
Solution: High temperatures can denature enzymes involved in photosynthesis, leading to a decrease in the rate of photosynthesis.

90. The oxygen released during photosynthesis comes from:
a) Carbon dioxide
b) Water
c) Glucose
d) Oxygen in the air
*Answer: b) Water*
Solution: Oxygen released during photosynthesis comes from the splitting of water molecules during the light-dependent reactions.

91. How does the stomata regulate gas exchange during photosynthesis?
a) By opening and closing to control the entry of light
b) By controlling the diffusion of oxygen and carbon dioxide
c) By releasing glucose into the atmosphere
d) By absorbing water from the soil
*Answer: b) By controlling the diffusion of oxygen and carbon dioxide*
Solution: Stomata open and close to regulate the exchange of gases, allowing carbon dioxide to enter and oxygen to exit the leaf.

92. What is the primary source of energy for photosynthesis?
a) Heat
b) Light
c) ATP
d) Glucose
*Answer: b) Light*
Solution: Light energy is absorbed by chlorophyll and used to power the process of photosynthesis.

93. During which phase of photosynthesis is oxygen produced?
a) Light-dependent reactions
b) Calvin cycle
c) Both a and b
d) None of the above
*Answer: a) Light-dependent reactions*
Solution: Oxygen is produced as a by product of the light-dependent reactions through the process of photolysis.

94. The Calvin cycle is also known as:
a) Light-dependent reactions
b) Carbon fixation
c) Photolysis
d) None of the above
*Answer: b) Carbon fixation*
Solution: The Calvin cycle is the stage of photosynthesis where carbon dioxide is converted into glucose.

95. Which enzyme is responsible for fixing carbon dioxide during the Calvin cycle?
a) Rubisco
b) ATP synthase
c) NADP reductase
d) Cytochrome c
*Answer: a) Rubisco*
Solution: Rubisco (Ribulose-1,5-bisphosphate carboxylase/oxygenase) is the enzyme that catalyzes the fixation of carbon dioxide during the Calvin cycle.

96. How many molecules of ATP and NADPH are required to fix one molecule of carbon dioxide during the Calvin cycle?
a) 1 ATP and 1 NADPH
b) 2 ATP and 2 NADPH
c) 3 ATP and 3 NADPH
d) 6 ATP and 6 NADPH
*Answer: c) 3 ATP and 3 NADPH*
Solution: The Calvin cycle requires 3 molecules of ATP and 3 molecules of NADPH to fix one molecule of carbon dioxide.

97. Which of the following is a by product of the Calvin cycle?
a) Oxygen
b) ATP
c) NADPH
d) Glucose
*Answer: d) Glucose*
Solution: Glucose is produced as a result of carbon fixation and reduction of CO2 during the Calvin cycle.

98. What is the primary function of the light-dependent reactions?
a) Production of glucose
b) Absorption of light energy
c) Fixation of carbon dioxide
d) Release of oxygen
*Answer: b) Absorption of light energy*
Solution: The primary function of the light-dependent reactions is to capture and convert light energy into chemical energy in the form of ATP and NADPH.

99. In photosynthesis, light energy is used to convert:
a) Carbon dioxide and water into glucose
b) Glucose and oxygen into carbon dioxide and water
c) Oxygen and water into carbon dioxide and glucose
d) Water and carbon dioxide into oxygen and ATP
*Answer: a) Carbon dioxide and water into glucose*
Solution: Light energy is used to convert carbon dioxide and water into glucose during photosynthesis.

100. Which of the following is NOT a factor that affects the rate of photosynthesis?
a) Light intensity
b) Carbon dioxide concentration
c) Temperature
d) pH of the soil
*Answer: d) pH of the soil*
Solution: While soil pH may affect nutrient availability for plants, it does not directly impact the rate of photosynthesis.

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