Life cycle in Chlamydomonas / Ulothrix/ Spirogya is

Options

A. haplontic
B. haplobiontic
C. diplontic
D. diplobiontic

Answer

### Step-by-Step Solution for the Life Cycle in Chlamydomonas, Ulothrix, and Spirogyra

1. **Understanding the Organisms**:
- Chlamydomonas, Ulothrix, and Spirogyra are all green algae belonging to the plant kingdom. They exhibit similar reproductive strategies and life cycles.

2. **Dominant Phase**:
- In all three organisms, the dominant phase of the life cycle is the haploid phase. This means that the majority of their life cycle is spent in the haploid state, where cells contain a single set of chromosomes.

3. **Haploid Phase**:
- The haploid phase is characterized by the presence of gametes. In Chlamydomonas, for example, gametes are produced through mitosis. When conditions are favorable, these gametes can fuse to form a diploid zygote.

4. **Formation of Zygote**:
- The zygote is formed by the fusion of two haploid gametes (isogamy or anisogamy, depending on the species). This zygote is diploid and undergoes a process called meiosis.

5. **Meiosis and Return to Haploid Phase**:
- The diploid zygote undergoes meiosis to produce haploid spores. These spores can germinate and develop into new haploid individuals, thus completing the life cycle.

6. **Duration of Phases**:
- The haploid phase is typically of a longer duration compared to the diploid phase, which is often short-lived and primarily exists to facilitate reproduction.

### Conclusion:
The life cycle in Chlamydomonas, Ulothrix, and Spirogyra is predominantly haploid, with a brief diploid phase represented by the zygote.

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