In which of the following zygote further develops to form a diploid structure ?

Options

A. Thallophyta
B. Bryophyta
C. Algae
D. Fungi

Answer

To determine in which of the following cases a zygote further develops to form a diploid structure, we need to understand the life cycles of different organisms, particularly focusing on the processes following zygote formation.

### Step-by-Step Solution:

1. **Understanding the Zygote**:
- A zygote is formed when two gametes (sperm and egg) fuse during fertilization. It is a diploid structure (2n), meaning it contains two sets of chromosomes.

2. **Life Cycle Types**:
- There are primarily two types of life cycles in plants: haplontic and diplontic.
- **Haplontic Life Cycle**: In this cycle, the main plant body is haploid (n). After fertilization, the diploid zygote undergoes meiosis to produce haploid spores, which then develop into the haploid plant body. This is typical in algae and fungi.
- **Diplontic Life Cycle**: In this cycle, the zygote remains diploid and undergoes mitosis to develop into an embryo, which will grow into the main diploid plant body. This is common in higher plants (angiosperms and gymnosperms).

3. **Exceptions in Algae**:
- While most algae exhibit a haplontic life cycle, there are exceptions. For example, the brown algae Fucus follows a diplontic life cycle where the zygote develops into a diploid structure.

4. **Conclusion**:
- Based on the understanding of the life cycles, the zygote will develop into a diploid structure in organisms that follow a diplontic life cycle. The most appropriate answer to the question is the example of Fucus, which is a type of algae that exhibits this exception.

### Final Answer:
The zygote further develops to form a diploid structure in the case of Fucus (option number 3).

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