MCQ 41:
Which of the following is NOT a phase of the Calvin cycle?
A) Carbon fixation
B) Reduction
C) Regeneration of RuBP
D) Photophosphorylation
Answer: D) Photophosphorylation
Explanation:
Photophosphorylation refers to the generation of ATP using light energy during the light-dependent reactions, not a phase of the Calvin cycle.
MCQ 42:
What is the primary function of the light-dependent reactions of photosynthesis?
A) To fix carbon dioxide
B) To generate ATP and NADPH
C) To produce glucose
D) To store water
Answer: B) To generate ATP and NADPH
Explanation:
The primary function of the light-dependent reactions is to capture light energy and convert it into chemical energy in the form of ATP and NADPH for use in the Calvin cycle.
MCQ 43:
In which type of plants does the enzyme PEP carboxylase play a crucial role?
A) C3 plants
B) C4 plants
C) CAM plants
D) All of the above
Answer: B) C4 plants
Explanation:
PEP carboxylase is critical in C4 plants for fixing carbon dioxide into a four-carbon compound before it enters the Calvin cycle.
MCQ 44:
Which of the following is true regarding the energy conversion in photosynthesis?
A) Light energy is converted to chemical energy.
B) Chemical energy is converted to light energy.
C) Heat energy is converted to electrical energy.
D) None of the above.
Answer: A) Light energy is converted to chemical energy.
Explanation:
Photosynthesis converts light energy from the sun into chemical energy stored in glucose.
MCQ 45:
What is the main advantage of C4 photosynthesis over C3 photosynthesis?
A) Higher oxygen production
B) More efficient water use in hot environments
C) Faster glucose production
D) Ability to thrive in low light
Answer: B) More efficient water use in hot environments
Explanation:
C4 photosynthesis allows plants to minimize water loss during photosynthesis, making it more efficient in hot and dry conditions.
MCQ 46:
Which molecule is formed during the splitting of water in photosynthesis?
A) Glucose
B) Oxygen
C) Carbon dioxide
D) Ethanol
Answer: B) Oxygen
Explanation:
The photolysis of water during the light-dependent reactions produces oxygen as a byproduct.
MCQ 47:
Which of the following best describes the relationship between photosynthesis and cellular respiration?
A) They are identical processes.
B) Photosynthesis produces glucose, which is then used in respiration.
C) Respiration occurs in plants only.
D) Photosynthesis and respiration occur in the same organelles.
Answer: B) Photosynthesis produces glucose, which is then used in respiration.
Explanation:
Photosynthesis produces glucose and oxygen, which are used in cellular respiration to generate ATP, thus supporting cellular functions.
MCQ 48:
In photosynthesis, what is the initial acceptor of carbon dioxide?
A) RuBP
B) ATP
C) NADPH
D) G3P
Answer: A) RuBP
Explanation:
In the Calvin cycle, carbon dioxide is initially fixed by the enzyme RuBisCO onto ribulose bisphosphate (RuBP), forming a 6-carbon compound.
MCQ 49:
What is the effect of intense light on the rate of photosynthesis?
A) It always increases the rate.
B) It can lead to photoinhibition.
C) It has no effect.
D) It decreases the rate.
Answer: B) It can lead to photoinhibition.
Explanation:
While increased light can enhance photosynthesis to a point, excessive light intensity can lead to photoinhibition, damaging the photosynthetic machinery.
MCQ 50:
Which of the following processes do NOT occur in the chloroplast?
A) Light-dependent reactions
B) Calvin cycle
C) Krebs cycle
D) Both A and B
Answer: C) Krebs cycle
Explanation:
The Krebs cycle occurs in the mitochondria, not in the chloroplasts, while the light-dependent reactions and Calvin cycle occur in the chloroplasts.
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