MCQ 31:
What role do carotenoids play in photosynthesis?
A) They directly capture light energy.
B) They provide structural support to chloroplasts.
C) They protect chlorophyll from photodamage.
D) They transport glucose.
Answer: C) They protect chlorophyll from photodamage.
Explanation:
Carotenoids serve as accessory pigments that help absorb excess light energy and protect chlorophyll from damage caused by excessive light.
MCQ 32:
In photosynthesis, the term “photolysis” refers to:
A) The breakdown of glucose.
B) The splitting of water molecules.
C) The fixation of carbon dioxide.
D) The synthesis of ATP.
Answer: B) The splitting of water molecules.
Explanation:
Photolysis is the process where light energy is used to split water molecules into oxygen, protons, and electrons during the light-dependent reactions.
MCQ 33:
What is the effect of increased carbon dioxide concentration on photosynthesis?
A) It decreases the rate of photosynthesis.
B) It has no effect.
C) It increases the rate of photosynthesis.
D) It leads to photorespiration.
Answer: C) It increases the rate of photosynthesis.
Explanation:
Higher concentrations of carbon dioxide generally increase the rate of photosynthesis until other factors become limiting.
MCQ 34:
What is the final electron acceptor in the light-dependent reactions of photosynthesis?
A) Carbon dioxide
B) Oxygen
C) NADP⁺
D) ATP
Answer: C) NADP⁺
Explanation:
NADP⁺ acts as the final electron acceptor in the light-dependent reactions, forming NADPH which is used in the Calvin cycle.
MCQ 35:
Which of the following statements is true about CAM plants?
A) They fix carbon dioxide during the day.
B) They open their stomata at night to minimize water loss.
C) They perform the Calvin cycle only at night.
D) They are adapted to cold environments.
Answer: B) They open their stomata at night to minimize water loss.
Explanation:
CAM (Crassulacean Acid Metabolism) plants open their stomata at night to absorb carbon dioxide and store it as malic acid, minimizing water loss during the day.
MCQ 36:
What is the primary role of the mesophyll cells in leaves?
A) To transport nutrients
B) To store water
C) To perform photosynthesis
D) To protect the plant from herbivores
Answer: C) To perform photosynthesis
Explanation:
Mesophyll cells are the main sites of photosynthesis in leaves, containing chloroplasts that capture light energy.
MCQ 37:
In which part of photosynthesis is glucose produced?
A) Light-dependent reactions
B) Light-independent reactions
C) Glycolysis
D) Krebs cycle
Answer: B) Light-independent reactions
Explanation:
Glucose is synthesized during the light-independent reactions (Calvin cycle) of photosynthesis using ATP and NADPH generated in the light-dependent reactions.
MCQ 38:
Which of the following light wavelengths is least effective in driving photosynthesis?
A) Red light
B) Blue light
C) Green light
D) Yellow light
Answer: C) Green light
Explanation:
Chlorophyll reflects green light, making it the least effective wavelength for photosynthesis compared to red and blue light, which are absorbed efficiently.
MCQ 39:
What is the primary source of energy for photosynthesis?
A) Heat energy
B) Chemical energy
C) Light energy
D) Electrical energy
Answer: C) Light energy
Explanation:
Photosynthesis relies on light energy from the sun to drive the conversion of carbon dioxide and water into glucose and oxygen.
MCQ 40:
In plants, which component is crucial for the synthesis of ATP during photosynthesis?
A) RuBisCO
B) Chlorophyll
C) Proton gradient
D) Glucose
Answer: C) Proton gradient
Explanation:
The proton gradient created across the thylakoid membrane during the light-dependent reactions drives ATP synthesis via chemiosmosis.
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