Dark reaction of photosynthesis is called so because

Options

A. It can also occur in dark
B. Cannot occur during day
C. Occurs more rapidly at night
D. It does not require light

Answer

### Step-by-Step Solution:

1. **Understanding the Dark Reaction**: The dark reaction of photosynthesis, also known as the Calvin cycle or C3 cycle, refers to the set of biochemical processes that occur in the stroma of chloroplasts in plants.

2. **Reason for the Name**: The term "dark reaction" can be misleading as it suggests that these reactions only occur in the absence of light. However, the key reason for this nomenclature is that these reactions do not directly require light energy to proceed.

3. **Energy Source**: Instead of relying on light energy, the dark reactions utilize energy stored in molecules such as ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate), which are produced during the light-dependent reactions of photosynthesis.

4. **Conclusion**: Therefore, the dark reaction is called so because it does not require light energy to occur, allowing it to take place both during the day and night as long as the necessary substrates (ATP and NADPH) are available.

5. **Final Answer**: The correct answer to the question is option 4: it does not require light.