Question

The dark reaction of photosynthesis occurs in

• A. Grana
• B. Matrix
• C. Cytoplasm
• D. Stroma

Answer 1

The correct option is D

Stroma

The correct option is option D.

Explanation for the correct option:

Option D:

1. The light reaction occurs in the thylakoid discs.
2. Water and oxygen are released in thylakoids.
3. The dark reaction occurs outside of the thylakoids i.e. in the stroma.
4. In this reaction, the energy from ATP and NADPH is used to fix carbon dioxide (CO₂).
5. The products of this reaction are sugar molecules and other organic molecules necessary for cell function and metabolism.

Explanation for the incorrect options:

Option A:

In the first step, the light reaction, chlorophyll in the grana absorbs light.

Option B:

The innermost matrix of chloroplasts, called the stroma, contains metabolic enzymes and multiple copies of the chloroplast genome.

Option C:

In the cytoplasm, all the cell organelles work together to carry out the cell metabolic processes.

Final answer: The dark reaction of photosynthesis occurs in stroma.