The life cycle of Ectocarpus and Polysiphonia is:

Options

A. Haplo-diplontic
B. Haplontic
C. Diplontic
D. Both haplontic and diplontic

Answer

To determine the life cycle of Ectocarpus and Polysiphonia, we need to analyze their reproductive patterns step by step.

### Step-by-Step Solution:

1. **Identify the Organisms**:
- Ectocarpus is a type of brown algae.
- Polysiphonia is a type of red algae.
- Both are classified under the group of organisms known as algae.

2. **Understand Algal Life Cycles**:
- Algae can exhibit different types of life cycles: haplontic, diplontic, and haplodiplontic.
- Haplontic life cycle: The dominant stage is haploid (gametophyte), and the diploid stage (sporophyte) is short-lived.
- Diplontic life cycle: The dominant stage is diploid (sporophyte), with a brief haploid stage (gametophyte).
- Haplodeplontic life cycle: Both haploid and diploid stages are multicellular and alternate with each other.

3. **Analyze Ectocarpus and Polysiphonia**:
- Both Ectocarpus and Polysiphonia exhibit a haplodiplontic life cycle.
- In this life cycle, the diploid sporophyte undergoes meiosis to produce haploid spores.
- These spores germinate to form a haploid gametophyte, which produces gametes.

4. **Process of Fertilization**:
- The gametes from the gametophyte fuse during fertilization (syngamy) to form a diploid zygote.
- The zygote develops into a new sporophyte, completing the cycle.

5. **Conclusion**:
- The life cycle of both Ectocarpus and Polysiphonia is classified as haplodiplontic.

### Final Answer:
The life cycle of Ectocarpus and Polysiphonia is **haplodiplontic**.

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