MCQ 81:
Which process is responsible for the synthesis of ATP during the light-dependent reactions of photosynthesis?
A) Photolysis
B) Chemiosmosis
C) Carbon fixation
D) Glycolysis
Answer: B) Chemiosmosis
Explanation:
Chemiosmosis is the process by which ATP is synthesized in the thylakoid membrane using the proton gradient created during the light-dependent reactions.
MCQ 82:
What is the first stable product of carbon fixation in the Calvin cycle for C3 plants?
A) G3P
B) RuBP
C) 3-PGA
D) Glucose
Answer: C) 3-PGA
Explanation:
In C3 plants, the first stable product of carbon fixation in the Calvin cycle is 3-phosphoglycerate (3-PGA), which is formed when RuBP combines with carbon dioxide.
MCQ 83:
Which of the following processes occurs in the thylakoid membranes?
A) The Calvin cycle
B) Water splitting
C) Carbon dioxide fixation
D) Oxygen uptake
Answer: B) Water splitting
Explanation:
Water splitting occurs in the thylakoid membranes during the light-dependent reactions, providing electrons and releasing oxygen.
MCQ 84:
What is the role of the enzyme ATP synthase in chloroplasts?
A) To fix carbon dioxide
B) To transport electrons
C) To synthesize ATP
D) To split water molecules
Answer: C) To synthesize ATP
Explanation:
ATP synthase synthesizes ATP from ADP and inorganic phosphate using the energy from the proton gradient established during the light-dependent reactions.
MCQ 85:
Which of the following molecules serves as the primary electron donor in the light-dependent reactions?
A) Water
B) NADPH
C) ATP
D) Glucose
Answer: A) Water
Explanation:
Water is the primary electron donor in the light-dependent reactions, where it is split to provide electrons and release oxygen.
MCQ 86:
In the context of photosynthesis, what does the term “photophosphorylation” refer to?
A) The conversion of light energy into chemical energy
B) The addition of a phosphate group to ADP to form ATP
C) The splitting of water molecules
D) The synthesis of glucose
Answer: B) The addition of a phosphate group to ADP to form ATP
Explanation:
Photophosphorylation specifically refers to the process of adding a phosphate group to ADP to form ATP using light energy during the light-dependent reactions.
MCQ 87:
What is the main advantage of photosynthesis for plants?
A) Producing oxygen
B) Storing energy
C) Absorbing carbon dioxide
D) All of the above
Answer: D) All of the above
Explanation:
Photosynthesis provides several advantages, including the production of oxygen, storage of energy in the form of glucose, and the absorption of carbon dioxide.
MCQ 88:
In CAM plants, during which part of the day do they fix carbon dioxide?
A) During the day
B) At night
C) During both day and night
D) During dawn only
Answer: B) At night
Explanation:
CAM plants fix carbon dioxide at night when they open their stomata, allowing them to conserve water.
MCQ 89:
What is the primary purpose of the light-harvesting complex in photosynthesis?
A) To transport sugars
B) To capture light energy
C) To fix carbon dioxide
D) To synthesize glucose
Answer: B) To capture light energy
Explanation:
The light-harvesting complex captures light energy and transfers it to the reaction center in the thylakoid membrane for photosynthesis.
MCQ 90:
Which of the following statements about chlorophyll b is true?
A) It absorbs primarily red light.
B) It is essential for the light-dependent reactions.
C) It absorbs light in the blue and orange wavelengths.
D) It is the main pigment used for photosynthesis.
Answer: C) It absorbs light in the blue and orange wavelengths.
Explanation:
Chlorophyll b absorbs light in the blue and orange wavelengths, complementing chlorophyll a in capturing light for photosynthesis.
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