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Multiple Choice
Do C4 and CAM plants also utilize the C3 (Calvin) cycle during photosynthesis?
A
Neither C4 nor CAM plants use the Calvin cycle at any stage.
B
Yes, both C4 and CAM plants use the C3 (Calvin) cycle to fix CO$_2$ after initial fixation steps.
C
C4 plants use the Calvin cycle, but CAM plants do not.
D
No, only C3 plants use the Calvin cycle; C4 and CAM plants use entirely different pathways.
Verified step by step guidance
1
Understand the Calvin cycle: The Calvin cycle, also known as the C3 cycle, is the set of light-independent reactions in photosynthesis where CO₂ is fixed into organic molecules like glucose. This cycle occurs in the stroma of chloroplasts and is common to all photosynthetic plants.
Learn about C4 plants: C4 plants have an additional mechanism to initially fix CO₂ into a four-carbon compound (hence the name C4). This occurs in mesophyll cells and is followed by the release of CO₂ in bundle-sheath cells, where the Calvin cycle takes place.
Learn about CAM plants: CAM (Crassulacean Acid Metabolism) plants fix CO₂ at night into organic acids, storing it for use during the day. During the day, the stored CO₂ is released and enters the Calvin cycle to produce sugars.
Clarify the relationship: Both C4 and CAM plants use the Calvin cycle as the final step to fix CO₂ into sugars. The initial fixation steps in these plants are adaptations to minimize photorespiration and conserve water, but the Calvin cycle is still essential for producing glucose.
Conclude: The correct answer is that both C4 and CAM plants utilize the Calvin cycle after their respective initial CO₂ fixation steps. This highlights the universal role of the Calvin cycle in photosynthesis across different plant types.