MCQ 11:
Which of the following conditions would likely increase the rate of photosynthesis?
A) High levels of oxygen
B) Low carbon dioxide concentration
C) Optimal light intensity
D) High humidity
Answer: C) Optimal light intensity
Explanation:
Photosynthesis increases with light intensity up to a certain point. After reaching saturation, other factors (such as CO₂ and temperature) will then limit the rate.
MCQ 12:
During which part of the photosynthesis process is ATP produced?
A) Calvin cycle
B) Photolysis
C) Light-dependent reactions
D) Dark reactions
Answer: C) Light-dependent reactions
Explanation:
ATP is produced in the light-dependent reactions of photosynthesis through the process of photophosphorylation.
MCQ 13:
Which structure in the chloroplasts is responsible for capturing light energy?
A) Stroma
B) Thylakoid
C) Outer membrane
D) Inner membrane
Answer: B) Thylakoid
Explanation:
Thylakoids are the membrane-bound structures within chloroplasts where the light-dependent reactions take place, capturing and converting light energy.
MCQ 14:
What is the main role of NADPH in photosynthesis?
A) Energy storage
B) Electron transport
C) Carbon fixation
D) Synthesis of glucose
Answer: B) Electron transport
Explanation:
NADPH serves as an electron carrier, transferring electrons and protons during the Calvin cycle to help reduce carbon compounds, ultimately leading to glucose synthesis.
MCQ 15:
Which of the following statements about photosynthesis is true?
A) It occurs only in green plants.
B) It is a process that releases carbon dioxide.
C) It converts light energy into chemical energy.
D) It occurs in the roots of plants.
Answer: C) It converts light energy into chemical energy.
Explanation:
Photosynthesis is the process by which plants convert light energy into chemical energy stored in glucose, primarily occurring in leaves.
MCQ 16:
What effect does increasing temperature have on the rate of photosynthesis, up to a certain limit?
A) It always decreases the rate.
B) It has no effect.
C) It generally increases the rate.
D) It causes chlorophyll to degrade.
Answer: C) It generally increases the rate.
Explanation:
As temperature increases, the rate of photosynthesis generally increases due to enhanced enzyme activity, up to an optimal temperature. Beyond this, the rate may decrease due to enzyme denaturation.
MCQ 17:
What is the role of water in photosynthesis?
A) It provides carbon.
B) It is the source of electrons.
C) It absorbs light.
D) It acts as a nutrient.
Answer: B) It is the source of electrons.
Explanation:
Water molecules are split during the light-dependent reactions to provide electrons, which are crucial for the formation of ATP and NADPH.
MCQ 18:
In which phase of photosynthesis is carbon dioxide fixed?
A) Light-dependent reactions
B) Calvin cycle
C) Photolysis
D) Glycolysis
Answer: B) Calvin cycle
Explanation:
The Calvin cycle is where carbon dioxide is fixed into organic molecules, eventually leading to glucose synthesis.
MCQ 19:
What is photophosphorylation?
A) The production of glucose from carbon dioxide.
B) The synthesis of ATP using light energy.
C) The conversion of oxygen into glucose.
D) The splitting of water molecules.
Answer: B) The synthesis of ATP using light energy.
Explanation:
Photophosphorylation refers to the process of ATP synthesis driven by light energy during the light-dependent reactions of photosynthesis.
MCQ 20:
Which of the following statements is true regarding C4 plants?
A) They use the Calvin cycle for carbon fixation only.
B) They are more efficient in hot and dry environments.
C) They do not require sunlight for photosynthesis.
D) They primarily photosynthesize at night.
Answer: B) They are more efficient in hot and dry environments.
Explanation:
C4 plants have a specialized mechanism that allows them to fix carbon dioxide efficiently in high temperatures and low moisture, reducing photorespiration.
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