MCQ 61:
Which of the following is the primary site for the light-dependent reactions in chloroplasts?
A) Stroma
B) Thylakoid membrane
C) Outer membrane
D) Inner membrane
Answer: B) Thylakoid membrane
Explanation:
The thylakoid membrane is where the light-dependent reactions occur, utilizing sunlight to generate ATP and NADPH.
MCQ 62:
What is produced as a waste product during photosynthesis?
A) Glucose
B) Oxygen
C) Carbon dioxide
D) Water
Answer: B) Oxygen
Explanation:
Oxygen is produced as a byproduct of the photolysis of water during the light-dependent reactions of photosynthesis.
MCQ 63:
What is the role of the RuBP in the Calvin cycle?
A) It captures light energy.
B) It fixes carbon dioxide.
C) It is regenerated to continue the cycle.
D) Both B and C.
Answer: D) Both B and C.
Explanation:
RuBP (ribulose bisphosphate) is essential in the Calvin cycle for fixing carbon dioxide and is regenerated to enable the cycle to continue.
MCQ 64:
Which of the following best describes photorespiration?
A) A process that enhances photosynthesis
B) A process that consumes oxygen and releases carbon dioxide
C) A process that occurs in the dark
D) A process that produces glucose
Answer: B) A process that consumes oxygen and releases carbon dioxide
Explanation:
Photorespiration occurs when RuBisCO fixes oxygen instead of carbon dioxide, leading to the consumption of oxygen and release of carbon dioxide, reducing photosynthetic efficiency.
MCQ 65:
In C4 plants, carbon dioxide is first fixed into which compound?
A) Ribulose bisphosphate (RuBP)
B) Phosphoenolpyruvate (PEP)
C) Glucose
D) Acetyl-CoA
Answer: B) Phosphoenolpyruvate (PEP)
Explanation:
In C4 plants, carbon dioxide is initially fixed into phosphoenolpyruvate (PEP) by the enzyme PEP carboxylase, forming a four-carbon compound.
MCQ 66:
Which of the following best describes the structure of chlorophyll?
A) A protein with a heme group
B) A carbohydrate with a lipid tail
C) A porphyrin ring with a magnesium ion
D) A nucleic acid with a sugar-phosphate backbone
Answer: C) A porphyrin ring with a magnesium ion
Explanation:
Chlorophyll consists of a porphyrin ring structure with a central magnesium ion, which is crucial for its light-absorbing properties.
MCQ 67:
What is the role of the stomata in photosynthesis?
A) To absorb sunlight
B) To fix carbon dioxide
C) To exchange gases
D) To transport water
Answer: C) To exchange gases
Explanation:
Stomata are small openings on leaves that allow for gas exchange, enabling carbon dioxide to enter and oxygen to exit during photosynthesis.
MCQ 68:
Which of the following types of plants is least likely to perform photosynthesis?
A) C3 plants
B) C4 plants
C) CAM plants
D) Fungi
Answer: D) Fungi
Explanation:
Fungi do not perform photosynthesis as they lack chlorophyll and are heterotrophic, obtaining nutrients from organic matter.
MCQ 69:
What is the function of the enzyme NADP⁺ reductase in photosynthesis?
A) Splits water molecules
B) Converts NADP⁺ to NADPH
C) Fixes carbon dioxide
D) Synthesizes ATP
Answer: B) Converts NADP⁺ to NADPH
Explanation:
NADP⁺ reductase catalyzes the reduction of NADP⁺ to NADPH during the light-dependent reactions, providing the reducing power needed for the Calvin cycle.
MCQ 70:
Which of the following wavelengths of light is most effective for driving photosynthesis?
A) Green light
B) Red light
C) Yellow light
D) Infrared light
Answer: B) Red light
Explanation:
Red light is most effectively absorbed by chlorophyll and is crucial for driving the photosynthetic process.
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