Question

Reactions that require CO2 take place in _____.

A. neither the light reactions nor the Calvin cycle
B. the chloroplast, but not as part of photosynthesis
C. both the light reactions and the Calvin cycle
D. the Calvin cycle alone
E. the light reactions alone

Answer 1

Reactions that require carbon dioxide take place in the calvin cycle alone

Answer: Option D

Explanation:

Calvin cycle is an important cycle that plays a major role in the synthesis of starch through the photosynthesis. Calvin takes place as a part of the dark reaction in the stroma.

It is the calvin cycle that requires carbon dioxide. It uses the ATP that are produced by the light reaction that takes place in the thylakoid with the help of chlorophyll that traps the sunlight.

Answer 2

Reactions that require CO2 take place in the Calvin cycle alone.

The Calvin cycle generates the reactions necessary for the fixation of carbon in a solid structure for the formation of glucose.

In the dark phase in which light no longer intervenes, the molecules formed in the light phase (ATP and NADPH2) participate in the reduction of carbon dioxide (CO2) through a series of reactions in which CO2 is combined with RDP (diphosphate ribulose) to form PGA.

The enzyme responsible for catalyzing the capture of CO2 by plants and has the ability to both carboxylate and oxygenate the RuBP substrate.

There are three reactions that occur in the dark phase or Calvin Cycle of photosynthesis:

• Fixation of CO2.

• Reduction of CO2 to organic compounds.

• Regeneration of the enzyme RuBP carboxylase.

Therefore, we can conclude that reactions that require CO2 take place in the Calvin cycle alone.

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