Reactions that require CO₂ take place in .
a. the Calvin cycle alone
b. the chloroplast, but not as part of photosynthesis
c. both the light reactions and the Calvin cycle
d. the light reactions alone
e. neither the light reactions nor the Calvin cycle

The correct answer is: A) the Calvin Cycle alone.

Explanation:

These reactions happen in cells capable of photosynthesis.

The only out of these reactions that require CO2 to take place is the Calvin Cycle. The Calvin Cycle is a series of biochemical processes that occur in the chloroplasts during photosynthesis. The Calvin Cycle uses carbon dioxide (CO2) and water to produce glucose, which will give energy to the cells.

The light reactions occur during photosynthesis in the presence of light and involving photophosphorylation. The light reaction does not make use of CO2, as it takes solar energy and converts it into NADPH and ATP.