Biochemistry : Calvin Cycle

Study concepts, example questions & explanations for Biochemistry

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Example Questions

Example Question #1 : Calvin Cycle Carbohydrate Intermediates

What happens during stage 1 of the Calvin cycle?

Possible Answers:

Fructose-6-phosphate becomes ribulose 5-phosphate

Carbon dioxide and ribulose 1,5-bisphosphate react to form 3-phosphoglycerate

ATP reacts with ribulose 5-phosphate to become ribulose 1,5-bisphosphate

2 ATP molecules react with 3-phosphoglycerate to form 1,3-bisphosphoglycerate

NADPH and 1,3 bisphosphoglycerate react to form glyceraldehyde-3-phosphate

Correct answer:

Carbon dioxide and ribulose 1,5-bisphosphate react to form 3-phosphoglycerate

Explanation:

All of the answer choices are steps in the Calvin cycle, but the only one that describes the first stage - fixation - is  and ribulose 1,5-bisphosphate reacting to form 3-phosphoglycerate.

Example Question #1 : Photosynthesis

What are the three stages of the Calvin cycle?

Possible Answers:

Carboxylation, reduction, and regeneration

Fixation, reduction, and regeneration

Fixation, carboxylation, and regeneration 

Reduction, oxidation, and regeneration

Fixation, oxidation, and regeneration

Correct answer:

Fixation, reduction, and regeneration

Explanation:

The stages of the Calvin cycle in the order that they occur are fixation, reduction, and then regeneration.  While carboxylation does occur as a part of the first stage, it is not what defines that stage.

Example Question #1 : Carbohydrate Metabolism

Which of the following is not true of the Calvin cycle?

Possible Answers:

The Calvin cycle occurs in the stroma of a chloroplast

The first step of the Calvin cycle is carbon fixation

The Calvin cycle does not need light to function

All of these are true of the Calvin cycle

NADPH and ATP are required to initiate the Calvin cycle

Correct answer:

The Calvin cycle does not need light to function

Explanation:

Despite the Calvin cycle's other name (light independent reactions), light is indirectly required for this process to function. All other choices are true of the Calvin cycle.

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