Photosynthesis: Light and Dark Reactions - Higher Difficulty Problems
Q. How does the concentration of CO2 affect the rate of photosynthesis?
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A.
Increases it indefinitely
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B.
Has no effect
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C.
Increases it to a point, then levels off
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D.
Decreases it
Solution
The rate of photosynthesis increases with CO2 concentration to a point, after which it levels off due to other limiting factors.
Correct Answer: C — Increases it to a point, then levels off
Q. In which part of the chloroplast do the light-dependent reactions of photosynthesis occur?
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A.
Stroma
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B.
Thylakoid membranes
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C.
Outer membrane
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D.
Inner membrane
Solution
The light-dependent reactions occur in the thylakoid membranes of the chloroplast.
Correct Answer: B — Thylakoid membranes
Q. What is the primary pigment involved in the light reactions of photosynthesis?
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A.
Chlorophyll a
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B.
Carotenoids
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C.
Chlorophyll b
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D.
Xanthophylls
Solution
Chlorophyll a is the primary pigment that absorbs light energy for photosynthesis.
Correct Answer: A — Chlorophyll a
Q. What is the primary role of ATP in photosynthesis?
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A.
To absorb light
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B.
To provide energy for reactions
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C.
To fix carbon
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D.
To transport electrons
Solution
ATP provides the energy necessary for various biochemical reactions in the Calvin cycle and other metabolic processes in photosynthesis.
Correct Answer: B — To provide energy for reactions
Q. What is the role of ATP and NADPH produced in the light reactions?
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A.
To provide energy and reducing power for the Calvin cycle
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B.
To produce glucose directly
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C.
To transport water
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D.
To release oxygen
Solution
ATP and NADPH provide the energy and reducing power needed for the Calvin cycle.
Correct Answer: A — To provide energy and reducing power for the Calvin cycle
Q. Which molecule acts as the electron carrier in the light reactions?
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A.
NADP+
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B.
FADH2
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C.
ATP
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D.
RuBP
Solution
NADP+ acts as the electron carrier, becoming NADPH after accepting electrons.
Correct Answer: A — NADP+
Q. Which molecule acts as the primary electron carrier in the light reactions?
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A.
NADP+
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B.
FADH2
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C.
ATP
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D.
ADP
Solution
NADP+ acts as the primary electron carrier, becoming NADPH after accepting electrons.
Correct Answer: A — NADP+
Q. Which molecule is produced as a byproduct of the light-dependent reactions?
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A.
Glucose
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B.
Oxygen
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C.
NADPH
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D.
ATP
Solution
Oxygen is produced as a byproduct of the light-dependent reactions when water molecules are split.
Correct Answer: B — Oxygen
Q. Which of the following statements about the light-independent reactions is true?
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A.
They require light directly
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B.
They occur in the thylakoid membranes
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C.
They produce glucose
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D.
They release oxygen
Solution
The light-independent reactions, also known as the Calvin cycle, produce glucose using ATP and NADPH generated in the light-dependent reactions.
Correct Answer: C — They produce glucose
Q. Which process occurs during the dark reactions of photosynthesis?
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A.
Photolysis of water
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B.
Carbon fixation
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C.
Light absorption
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D.
Oxygen release
Solution
Carbon fixation occurs during the dark reactions, specifically in the Calvin cycle.
Correct Answer: B — Carbon fixation
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