The diploid stage is represented by one celled zygote only in

Options

A. Chlamydomonas
B. Spirogyra
C. both 1 and 2
D. Funaria

Answer

To solve the question "The diploid stage is represented by one celled zygote only in", we will analyze the options provided and understand the life cycles of the organisms mentioned.

### Step-by-Step Solution:

1. **Understanding Diploid Stage**:
- The diploid stage refers to the phase in the life cycle where the organism has two sets of chromosomes (2n). In many plants and algae, this stage is represented by a zygote.

2. **Identifying Life Cycles**:
- There are three types of life cycles in plants and algae:
- **Haplontic Life Cycle**: The dominant phase is haploid (n), and the diploid phase is represented only by a single-celled zygote.
- **Diplontic Life Cycle**: The dominant phase is diploid (2n), and the haploid phase is represented by gametes.
- **Haplodiplontic Life Cycle**: Both haploid and diploid phases are multicellular.

3. **Analyzing Chlamydomonas**:
- Chlamydomonas exhibits a **haplontic life cycle**. Here, the only diploid stage is the single-celled zygote formed after fertilization. This zygote undergoes meiosis to produce haploid spores.

4. **Analyzing Spirogyra**:
- Spirogyra also follows a **haplontic life cycle**. Similar to Chlamydomonas, the diploid stage is represented by a single-celled zygote formed after the fusion of gametes.

5. **Analyzing Funeria**:
- Funeria, on the other hand, exhibits a **haplodiplontic life cycle**. In this cycle, both the gametophyte (haploid) and sporophyte (diploid) stages are multicellular. Hence, the diploid stage is not represented by a single-celled zygote.

6. **Conclusion**:
- Since both Chlamydomonas and Spirogyra represent the diploid stage as a single-celled zygote, the correct answer is that the diploid stage is represented by one celled zygote only in both Chlamydomonas and Spirogyra.

### Final Answer:
The diploid stage is represented by one celled zygote only in **both Chlamydomonas and Spirogyra**.

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