Life cycle of Ectocarpus and Fucus respectivley are

Options

A. Haplontic, Diplontic
B. Diplontic, Haplodiplontic
C. Haplodiplontic, Diplontic
D. Haplodiplontic, Haplontic

Explanation

### Step-by-Step Solution:

1. **Identify the Organisms**: The question asks about the life cycles of two brown algae: Ectocarpus and Fucus.

2. **Determine the Type of Life Cycle for Ectocarpus**:
- Ectocarpus exhibits a **haplodeplontic life cycle**.
- In this type of life cycle, both haploid (gametophyte) and diploid (sporophyte) stages are present and can be dominant at different times.

3. **Explain the Life Cycle of Ectocarpus**:
- The life cycle begins with the **sporophyte** stage, which is diploid.
- Upon meiosis, the sporophyte produces **haploid spores**.
- These spores develop into **gametophytes**.
- The gametophytes undergo **mitosis** to produce gametes.
- Fertilization (syngamy) of gametes leads to the formation of a **diploid zygote**, which develops into a new sporophyte.

4. **Determine the Type of Life Cycle for Fucus**:
- Fucus exhibits a **diplontic life cycle**.
- In this life cycle, the diploid phase is dominant, and the haploid phase is reduced.

5. **Explain the Life Cycle of Fucus**:
- The life cycle starts with the **diploid sporophyte**.
- This sporophyte undergoes **meiosis** to produce haploid gametes directly.
- The gametes are formed through meiosis, and gametogenesis occurs simultaneously.
- After fertilization of the gametes (syngamy), a diploid zygote is formed, which develops into a new sporophyte.

6. **Conclusion**:
- The life cycle of Ectocarpus is **haplodeplontic**.
- The life cycle of Fucus is **diplontic**.
- Therefore, the correct answer is that the life cycles of Ectocarpus and Fucus are respectively **haplodeplontic and diplontic**.

### Final Answer:
The life cycle of Ectocarpus and Fucus respectively are **haplodeplontic and diplontic**.

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