The Calvin cycle and light reactions relationship?

The Calvin cycle and light reactions relationship?

• A. The Calvin cycle uses ATP and NADPH from the light reactions to fix carbon dioxide into carbohydrate.
• B. The Calvin cycle generates ATP and NADPH for the light reactions.
• C. The light reactions fix carbon dioxide during the night.
• D. The light reactions produce glucose directly.

Answer: (A)

In photosynthesis, energy flows from the light reactions to the Calvin cycle. The light reactions capture light energy to make ATP and NADPH and release O2. The Calvin cycle, which happens in the chloroplast stroma, uses those ATP and NADPH molecules as energy and reducing power to convert carbon dioxide into carbohydrate. This means the Calvin cycle relies on the products of the light reactions to fix CO2 into sugars like glucose. So the best description is that the Calvin cycle uses ATP and NADPH from the light reactions to fix carbon dioxide into carbohydrate. The other statements don’t fit: the Calvin cycle does not generate ATP or NADPH—those are consumed; the light reactions don’t fix CO2 themselves; and the light reactions do not produce glucose directly.

In photosynthesis, energy flows from the light reactions to the Calvin cycle. The light reactions capture light energy to make ATP and NADPH and release O2. The Calvin cycle, which happens in the chloroplast stroma, uses those ATP and NADPH molecules as energy and reducing power to convert carbon dioxide into carbohydrate. This means the Calvin cycle relies on the products of the light reactions to fix CO2 into sugars like glucose.

So the best description is that the Calvin cycle uses ATP and NADPH from the light reactions to fix carbon dioxide into carbohydrate. The other statements don’t fit: the Calvin cycle does not generate ATP or NADPH—those are consumed; the light reactions don’t fix CO2 themselves; and the light reactions do not produce glucose directly.