Question

Which one of the following seldom acts as a limiting factor in photosynthesis?

• A. Light
• B. Oxygen
• C. Chlorophyll
• D. Carbon dioxide

Answer 1

The correct option is B

Oxygen

The correct option is B.

Explanation of correct option:

1. For photosynthesis to take place, plants need a number of things, including photosynthetic pigments, carbon dioxide, water, light energy, and the right temperature.
2. Since oxygen is a byproduct of photosynthesis rather than an element needed for it, it is never a limiting factor.
3. The key environmental variables that influence the rate of photosynthesis are temperature, carbon dioxide content, and light intensity. These are referred to as photosynthesis's limiting factors.
4. Even if the other two are at the plant's optimal levels, the rate of photosynthesis will decrease if any one of these components is below that level.

Explanation of incorrect options:

Option A

1. Light is the limiting factor.
2. The rate of photosynthesis increases as light intensity increases.

Option C

1. Chlorophyll is a green pigment.
2. It traps sunlight for photosynthesis.

Option D

1. Carbon dioxide is a limiting factor.
2. It is necessary for the stage of photosynthesis that doesn't require light, when CO₂ and the five-carbon molecule ribulose bisphosphate (RuBP) are mixed during carbon fixation.

Final answer: Oxygen is not a limiting factor in photosynthesis.