Question

After karyogamy followed by meiosis, spores are produced exogenously in

• A. Neurospora
• B. Agaricus
• C. Alternaria
• D. Saccharomyces

Answer 1

The Correct Option is B

To solve this question, we need to understand the life cycle processes in fungi, particularly focusing on karyogamy, meiosis, and spore formation.

Karyogamy is the process of nuclear fusion, where two haploid nuclei combine to form a diploid nucleus. This is followed by meiosis, which is the key event of sexual reproduction, leading to the formation of haploid cells or spores.

The spores can be produced either endogenously or exogenously:

1. Endogenous spore production occurs inside a structure. For example, in Saccharomyces (yeast), spores are formed inside the ascus.
2. Exogenous spore production occurs on the outside of the structure. Exogenously produced spores are seen in basidia or conidia. In Agaricus (a genus of basidiomycete fungi), the spores are produced on the outside of the basidia, hence exogenously.

Now, let's evaluate the given options:

• Neurospora: This fungus forms spores inside an ascus, which are endogenous.
• Agaricus: This is a basidiomycete fungus, like the common mushroom, where spores are produced exogenously on the basidia.
• Alternaria: This is a deuteromycete and produces conidia exogenously, not directly related to karyogamy followed by meiosis.
• Saccharomyces: This yeast produces spores endogenously within an ascus.

Based on the above explanations, the correct answer is Agaricus as it produces spores exogenously after karyogamy and meiosis.