Question

Which one of the following processes does not occur during photosynthesis?

• A. Absorption of light energy by chlorophyll
• B. Conversion of light energy into chemical energy
• C. Reduction of CO\(_2\) into carbohydrate
• D. Breakdown of glucose into pyruvic acid

Hint:

The breakdown of glucose into pyruvic acid occurs in cellular respiration, not photosynthesis.

Answer 1

The Correct Option is D

Photosynthesis is the process by which plants, algae, and some bacteria convert light energy into chemical energy in the form of glucose. The essential steps of photosynthesis include the absorption of light energy, conversion into chemical energy, and the reduction of carbon dioxide (CO\(_2\)) to form carbohydrates.

Step 1: Absorption of light energy by chlorophyll.
This is the first step of photosynthesis, where chlorophyll absorbs light energy, primarily from sunlight, to power the rest of the process. This occurs in the light-dependent reactions. Therefore, option (A) is a correct part of photosynthesis.

Step 2: Conversion of light energy into chemical energy.
In the light-dependent reactions of photosynthesis, light energy is indeed converted into chemical energy. This is essential for the formation of ATP and NADPH, which are later used in the Calvin cycle to form carbohydrates. So, option (B) is also part of the process.

Step 3: Reduction of CO\(_2\) into carbohydrate.
In the Calvin cycle (the light-independent reactions), CO\(_2\) is reduced to form glucose and other carbohydrates. This process is essential for the production of sugars in plants, making option (C) a correct part of photosynthesis.

Step 4: Breakdown of glucose into pyruvic acid.
The breakdown of glucose into pyruvic acid is a part of cellular respiration, not photosynthesis. In respiration, glucose is broken down to produce ATP, whereas in photosynthesis, glucose is synthesized. Therefore, option (D) does not occur during photosynthesis.

Step 5: Conclusion.
The process that does not occur during photosynthesis is the breakdown of glucose into pyruvic acid. The correct answer is (D).