Question

Which of the following is not considered a primary limiting factor for the rate of photosynthesis?

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

Hint:

\[ \boxed{\text{Limiting factors → Light, CO}_2, \text{Temperature}} \] \[ \boxed{\text{O}_2 \rightarrow \text{photorespiration, not limiting factor}} \]

Answer 1

The Correct Option is D

Concept: The rate of photosynthesis is controlled by several limiting factors such as light, CO$_2$, and temperature. Oxygen is not a limiting factor; instead, it can act as an inhibitor due to photorespiration.

Step 1: Identify limiting factors.
Primary limiting factors include: \[ \boxed{\text{Light intensity, CO}_2 \text{ concentration, temperature}} \]

Step 2: Check oxygen role.
Oxygen does not directly limit photosynthesis rate. Instead, high oxygen may increase photorespiration. \[ \boxed{\text{Oxygen is NOT a primary limiting factor}} \]

Step 3: Select correct option.
Hence, \[ \boxed{\textbf{Option (D)}} \]