Heterocysts are present in `BGA` which participate in __________and lack ____________.

Options

A. `N_(2)-"fix",PS-II`
B. `N_(2)-"fix",PS-I`
C. denitrification, `PS-II`
D. dentrification, `PS-I`

Answer

**Step-by-Step Solution:**

1. **Understanding Heterocysts**: Heterocysts are specialized cells found in certain types of cyanobacteria, commonly referred to as blue-green algae (BGA). They play a crucial role in the nitrogen cycle.

2. **Function of Heterocysts**: The primary function of heterocysts is to fix atmospheric nitrogen. This means they convert nitrogen gas (N₂) from the atmosphere into ammonia (NH₃), which can then be utilized by plants and other organisms.

3. **Absence of Photosystem II**: Heterocysts lack Photosystem II, which is essential for the process of photosynthesis. This absence is significant because it means that heterocysts do not produce oxygen during nitrogen fixation.

4. **Filling in the Blanks**: Based on the above understanding, we can fill in the blanks in the question:
- Heterocysts are present in BGA which participate in **nitrogen fixation** and lack **Photosystem II**.

**Final Answer**: Heterocysts are present in BGA which participate in **nitrogen fixation** and lack **Photosystem II**.

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