Which of the following factors affects the rate of photosynthesis the least?

• A. Light intensity
• B. Carbon dioxide concentration
• C. Oxygen concentration
• D. Temperature

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. It primarily involves the absorption of light, the use of carbon dioxide (CO₂), and water (H₂O), and the release of oxygen (O₂) as a byproduct.
2. Identify the key factors that influence photosynthesis: The rate of photosynthesis is affected by light intensity, carbon dioxide concentration, and temperature. These factors directly impact the efficiency of the light-dependent and light-independent reactions in photosynthesis.
3. Analyze the role of oxygen concentration: Oxygen is a byproduct of photosynthesis and does not play a direct role in the photosynthetic reactions. Therefore, changes in oxygen concentration have minimal impact on the rate of photosynthesis compared to other factors like light intensity, CO₂ concentration, and temperature.
4. Compare the other factors: Light intensity affects the energy available for the light-dependent reactions. Carbon dioxide concentration impacts the Calvin cycle, where CO₂ is fixed into glucose. Temperature influences enzyme activity, such as that of Rubisco, which is critical for the Calvin cycle. These factors are directly involved in photosynthesis and significantly affect its rate.
5. Conclude that oxygen concentration affects the rate of photosynthesis the least: Since oxygen is not directly involved in the photosynthetic reactions, its concentration has the least effect on the rate of photosynthesis compared to light intensity, carbon dioxide concentration, and temperature.