Heterocysts present in Anabaena is specialised for

Options

A. `N_2` fixation
B. Food storage
C. Fission
D. Sexual reproduction

Answer

### Step-by-Step Solution:

1. **Identify the Organism**: The question refers to "Anabaena," which is a type of cyanobacteria, also known as blue-green algae.

2. **Understand the Function of Heterocysts**: Heterocysts are specialized cells found in certain cyanobacteria, including Anabaena. Their primary function is to facilitate the process of nitrogen fixation.

3. **Define Nitrogen Fixation**: Nitrogen fixation is the process by which atmospheric nitrogen (N₂) is converted into a form that can be utilized by living organisms, such as ammonia (NH₃). This is crucial for the growth of plants and other organisms that cannot use atmospheric nitrogen directly.

4. **Analyze the Role of Heterocysts**: Heterocysts provide an anaerobic environment that is necessary for the nitrogen-fixing bacteria to function effectively. They contain the enzyme nitrogenase, which is sensitive to oxygen; hence, the specialized structure helps in protecting this enzyme from oxygen.

5. **Consider Other Functions**: The question may present options such as food storage, fission, or sexual reproduction. However, these functions are not associated with heterocysts. The primary and most significant role of heterocysts in Anabaena is nitrogen fixation.

6. **Select the Correct Answer**: Based on the analysis, the correct answer to the question "Heterocysts present in Anabaena is specialized for" is nitrogen fixation.

### Final Answer:
Heterocysts present in Anabaena are specialized for nitrogen fixation.

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