How many turns of the Calvin cycle are needed before one G3P leaves it?
AOne turn
BTwo turns
CThree turns
DSix turns
Answer & Solution
Correct answer: C. Three turns
1. Each turn fixes only one carbon dioxide molecule.
2. G3P carries three carbons, so three fixations are needed to release one.
3. After three turns of the cycle, a three-carbon molecule of G3P leaves the cycle to become part of a carbohydrate molecule.
4. The remaining G3P molecules stay in the cycle to be regenerated into RuBP.
5. Six turns would be needed for a full glucose, since glucose takes two G3P.
_Source: OpenStax Biology for AP(R) Courses (CC BY 4.0), Ch 8 'Photosynthesis', sections 8.1-8.3_
Related questions
The light-independent reactions still depend on the light reactions because they need:Roughly what share of the oxygen produced in a leaf is used by the leaf's own mitochondriaLight of energy higher than blue damages pigment molecules in a process called:Bacteria that build sugars using energy from inorganic chemicals rather than light are:The coal and petroleum burned today store sunlight captured by photosynthesis roughly:The three-carbon carbohydrate that carbon dioxide is first fixed into is:The flow of hydrogen ions through ATP synthase is called:Energy hops from chlorophyll to chlorophyll before reaching the reaction centre, taking ab