alleryStart learning →How many turns of the cycle are needed before a three-carbon molecule can leave to join a carbohydrate?
AOne turn
BTwo turns
CThree turns
DSix turns
Answer & Solution
Correct answer: C. Three turns
1. Only one carbon dioxide molecule is incorporated per turn.
2. After three cycles, a three-carbon molecule of glyceraldehyde 3-phosphate leaves the cycle.
3. It then becomes part of a carbohydrate molecule.
4. The remaining molecules stay in the cycle to be regenerated into the five-carbon acceptor.
_Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 8 "Photosynthesis", section 8.3 Using Light Energy to Make Organic Molecules_
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