Question

1. which of the following correctly describes how the light-dependent reactions and calvin cycle are connected?

the calvin cycle produces atp used in the light reactions.
the light-dependent reactions provide co₂ for the calvin cycle.
the light-dependent reactions produce atp and nadph needed for the calvin cycle.
the calvin cycle produces oxygen for the light reactions.

Explanation:

• Analyze each option:
• First option: The Calvin Cycle consumes ATP, not produce it for light reactions. So this is incorrect.
• Second option: The light - dependent reactions do not provide $\ce{CO_2}$ for the Calvin Cycle. $\ce{CO_2}$ is taken from the environment for the Calvin Cycle. So this is incorrect.
• Third option: In photosynthesis, the light - dependent reactions (in the thylakoids) use light energy to produce ATP and NADPH. These ATP and NADPH are then used in the Calvin Cycle (in the stroma) to convert $\ce{CO_2}$ into glucose. So this option correctly describes the connection.
• Fourth option: The light - dependent reactions produce oxygen as a by - product, not the Calvin Cycle. So this is incorrect.

Answer:

The light - dependent reactions produce ATP and NADPH needed for the Calvin Cycle. (The option with this description)