In yeast the sexual reproduction is by conjugation . After fusion the zygotic nucleus divides meiotically and forms haploid spores. The unicellular structure with haploid spores is

Options

A. Sporangium
B. Gametangium
C. Ascus
D. Zoosporangium.

Answer

To solve the question about the unicellular structure with haploid spores in yeast, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Yeast Reproduction**: Yeast primarily reproduces both asexually and sexually. The question specifically refers to sexual reproduction, which occurs through a process called conjugation.

2. **Conjugation Process**: During conjugation, two yeast cells come together and their nuclei fuse to form a zygote. This zygote then undergoes meiosis, a type of cell division that reduces the chromosome number by half, resulting in haploid spores.

3. **Formation of Spores**: After meiosis, the haploid spores are formed. In yeast, these spores are known as ascospores.

4. **Identifying the Structure**: The question asks for the unicellular structure that contains these haploid spores. In yeast, the structure that contains the ascospores is called an "ascus."

5. **Conclusion**: Therefore, the correct answer to the question is that the unicellular structure with haploid spores in yeast is called an "ascus."

### Final Answer:
The unicellular structure with haploid spores in yeast is called an **ascus**.

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