MCQ 91:
What type of energy is stored in glucose produced during photosynthesis?
A) Thermal energy
B) Kinetic energy
C) Chemical energy
D) Electrical energy
Answer: C) Chemical energy
Explanation:
The energy stored in glucose produced during photosynthesis is chemical energy, which can be used by the plant for growth and metabolism.
MCQ 92:
Which structure in chloroplasts is responsible for the formation of a proton gradient?
A) Thylakoid lumen
B) Stroma
C) Granum
D) Outer membrane
Answer: A) Thylakoid lumen
Explanation:
The thylakoid lumen is where protons accumulate during the light-dependent reactions, creating a proton gradient used to generate ATP.
MCQ 93:
What is the main purpose of the light-dependent reactions of photosynthesis?
A) To produce glucose
B) To convert light energy into chemical energy
C) To absorb carbon dioxide
D) To release oxygen
Answer: B) To convert light energy into chemical energy
Explanation:
The main purpose of the light-dependent reactions is to convert light energy into chemical energy in the form of ATP and NADPH.
MCQ 94:
In which part of the chloroplast do the light-independent reactions take place?
A) Thylakoid membrane
B) Granum
C) Stroma
D) Outer membrane
Answer: C) Stroma
Explanation:
The light-independent reactions, also known as the Calvin cycle, occur in the stroma of chloroplasts.
MCQ 95:
What is the primary role of the enzyme PEP carboxylase in photosynthesis?
A) To fix oxygen
B) To transport glucose
C) To fix carbon dioxide in C4 plants
D) To synthesize ATP
Answer: C) To fix carbon dioxide in C4 plants
Explanation:
PEP carboxylase is crucial for fixing carbon dioxide in C4 plants, allowing them to efficiently utilize CO2 even in low concentrations.
MCQ 96:
What is the effect of increased temperature on photosynthesis in most plants?
A) It always increases the rate of photosynthesis.
B) It has no effect.
C) It can lead to denaturation of enzymes and decrease photosynthesis.
D) It increases the rate of respiration only.
Answer: C) It can lead to denaturation of enzymes and decrease photosynthesis.
Explanation:
Increased temperatures can enhance photosynthesis to a point, but excessive heat can denature enzymes, reducing the rate of photosynthesis.
MCQ 97:
Which of the following is NOT a product of the light-dependent reactions?
A) ATP
B) NADPH
C) Oxygen
D) Glucose
Answer: D) Glucose
Explanation:
Glucose is produced during the light-independent reactions (Calvin cycle), not during the light-dependent reactions.
MCQ 98:
What molecule serves as the primary electron carrier in the light-dependent reactions?
A) NADH
B) ATP
C) NADPH
D) FADH₂
Answer: C) NADPH
Explanation:
NADPH serves as the primary electron carrier, transporting electrons to the Calvin cycle for the synthesis of glucose.
MCQ 99:
Which pigment is responsible for the yellow and orange colors in plants?
A) Chlorophyll
B) Carotenoids
C) Anthocyanins
D) Xanthophylls
Answer: B) Carotenoids
Explanation:
Carotenoids are responsible for the yellow and orange colors in plants and also assist in photosynthesis by capturing light energy.
MCQ 100:
What is the role of light energy in photosynthesis?
A) To break down glucose
B) To convert chemical energy into kinetic energy
C) To excite electrons and initiate the light-dependent reactions
D) To synthesize starch
Answer: C) To excite electrons and initiate the light-dependent reactions
Explanation:
Light energy excites electrons in chlorophyll, initiating the light-dependent reactions of photosynthesis and leading to the synthesis of ATP and NADPH
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