Multiple Choice
Where in a plant cell does the Calvin cycle take place?
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13. Photosynthesis
Calvin Cycle
Multiple Choice
The enzyme rubisco combines RuBP with a carbon atom from:
A
Glucose
B
ATP
C
Carbon monoxide
D
Organic compounds
E
Carbon dioxide
F
NADPH
Verified step by step guidance1
Understand the role of the enzyme rubisco: Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) is a crucial enzyme in the process of photosynthesis, specifically in the Calvin cycle, where it catalyzes the first major step of carbon fixation.
Identify the substrate involved: Rubisco catalyzes the reaction between ribulose-1,5-bisphosphate (RuBP) and carbon dioxide (CO2), not glucose, ATP, carbon monoxide, or other organic compounds.
Clarify the process of carbon fixation: In the Calvin cycle, carbon fixation is the process of converting inorganic carbon (CO2) into organic compounds. Rubisco facilitates this by attaching CO2 to RuBP, forming an unstable 6-carbon intermediate that quickly splits into two molecules of 3-phosphoglycerate (3-PGA).
Differentiate between the options: Glucose, ATP, carbon monoxide, organic compounds, and NADPH are not directly involved in the initial carbon fixation step catalyzed by rubisco. Glucose is a product of the Calvin cycle, ATP and NADPH are energy carriers used later in the cycle, and carbon monoxide is not used in photosynthesis.
Conclude with the correct substrate: The correct answer is carbon dioxide, as it is the molecule that rubisco combines with RuBP during the carbon fixation step of the Calvin cycle.
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