Find odd one w.r.t. haplontic life cycle

Options

A. Ectocarpus
B. Ulothrix
C. Spirogyra
D. Chlamydomonas

Answer

To solve the question of finding the odd one out with respect to the haplontic life cycle among the given options (Ectocarpus, Eulothrix, Pyrogyra, and Chlamydomonas), we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Haplontic Life Cycle**:
- The haplontic life cycle is characterized by the organism being predominantly haploid. In this cycle, the gametophyte is the main form, and it produces gametes that are also haploid. After fertilization, a diploid zygote is formed, which undergoes meiosis to produce haploid spores, continuing the cycle.

2. **Analyze the Options**:
- **Ectocarpus**: This organism is known to exhibit a haplodiplontic life cycle, which includes both haploid and diploid stages, indicating an alteration of generations.
- **Eulothrix**: This is an alga that follows a haplontic life cycle, where the dominant phase is haploid.
- **Pyrogyra**: This alga also demonstrates a haplontic life cycle, with a dominant haploid phase.
- **Chlamydomonas**: This is another example of an alga that follows the haplontic life cycle.

3. **Identify the Odd One Out**:
- Upon reviewing the life cycles of the organisms listed, Ectocarpus is the only one that does not follow the haplontic life cycle. Instead, it shows a haplodiplontic life cycle, which involves both haploid and diploid stages.

4. **Conclusion**:
- Therefore, the odd one out with respect to the haplontic life cycle is **Ectocarpus**.

### Final Answer:
**Ectocarpus** is the odd one out with respect to the haplontic life cycle.

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