Spirogyra is a sexually reproducing alga in which vegetative thallus is haploid. In Spirogyra, meiosis

Options

A. never occurs
B. occurs at time of gamete production
C. occurs after fertilisation
D. occurs during vegetative growth.

Answer

**Step-by-Step Text Solution:**

1. **Understanding Spirogyra**: Spirogyra is a type of green alga that reproduces sexually. It is important to note that the vegetative thallus (the main body) of Spirogyra is haploid, meaning it contains one set of chromosomes.

2. **Life Cycle of Spirogyra**: Spirogyra exhibits a haplontic life cycle, which means that the dominant phase of its life cycle is haploid. In this cycle, the organism primarily exists in the haploid state.

3. **Meiosis in Spirogyra**: The question asks when meiosis occurs in Spirogyra. Meiosis is a type of cell division that reduces the chromosome number by half and is crucial for sexual reproduction.

4. **Timing of Meiosis**: In Spirogyra, meiosis occurs after fertilization. When two haploid gametes (reproductive cells) fuse during fertilization, they form a diploid zygote (2n).

5. **Post-Fertilization Meiosis**: After the formation of the diploid zygote, meiosis takes place to restore the haploid state. This process reduces the diploid zygote back to haploid cells, allowing the organism to continue its haplontic life cycle.

6. **Conclusion**: Therefore, the correct answer to the question is that meiosis in Spirogyra occurs after fertilization.

**Final Answer**: Meiosis in Spirogyra occurs after fertilization.

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