How does reducing the amount of light energy available to a plant affect the products of photosynthesis?

• A. It increases the production of glucose and oxygen.
• B. It has no effect on the production of glucose and oxygen.
• C. It decreases the production of glucose and oxygen.
• D. It causes the plant to produce more carbon dioxide.

Answer: (C)

Verified step by step guidance

1. Understand the process of photosynthesis: Photosynthesis is the process by which plants convert light energy into chemical energy stored in glucose. The general equation for photosynthesis is: $6_{\mathrm{CO}}+6_H{2}_O\to C_{6_H}$. Light energy is a critical input for this process.
2. Recognize the role of light energy: Light energy is absorbed by chlorophyll in the chloroplasts of plant cells. This energy drives the light-dependent reactions, which produce ATP and NADPH, essential for the Calvin cycle (light-independent reactions) where glucose is synthesized.
3. Analyze the impact of reduced light energy: If the amount of light energy is reduced, the light-dependent reactions will produce less ATP and NADPH. This directly limits the energy and reducing power available for the Calvin cycle, thereby decreasing the production of glucose.
4. Understand the relationship between glucose and oxygen production: Oxygen is a byproduct of the light-dependent reactions, specifically during the splitting of water molecules (photolysis). Reduced light energy means less photolysis, which decreases oxygen production alongside glucose.
5. Conclude the effect: Reducing light energy decreases the production of both glucose and oxygen because the light-dependent reactions are less efficient, and the Calvin cycle has fewer resources to synthesize glucose.