In life cycle of Spirogyra, a brief period of tetranucleate condition occurs in
(a) Vegetative cells
(b) Germinating zygospores
(c) Gametangium
(d) Holdfast

Options

A. Vegetative cells
B. Germinating zygospores
C. Gametangium
D. Holdfast.

Answer

To solve the question regarding the life cycle of Spirogyra and the tetranucleate condition, we will analyze each option step by step.

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks which structure in the life cycle of Spirogyra experiences a brief period of tetranucleate condition.

2. **Analyzing Option (a) Vegetative cells**:
- Vegetative cells are formed through mitosis and do not undergo meiosis.
- They do not exhibit a tetranucleate condition, as they typically contain one nucleus.
- **Conclusion**: This option is incorrect.

3. **Analyzing Option (b) Germinating zygospores**:
- Zygospores are formed through sexual reproduction via conjugation between two different strains (positive and negative).
- After fusion, the zygospore initially contains four nuclei (tetranucleate condition).
- Subsequently, three of these nuclei degenerate, and one nucleus undergoes germination.
- **Conclusion**: This option is correct as it describes the tetranucleate condition occurring briefly.

4. **Analyzing Option (c) Gametangium**:
- Gametangia are structures that produce gametes (male and female).
- They do not exist in a tetranucleate condition; they typically have a single nucleus.
- **Conclusion**: This option is incorrect.

5. **Analyzing Option (d) Holdfast**:
- The holdfast is a structure that anchors the organism to a substrate.
- It does not undergo any nuclear division and does not have a tetranucleate condition.
- **Conclusion**: This option is incorrect.

### Final Answer:
The correct answer is **(b) Germinating zygospores**.

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