Which of the following structures carries out sexual reproduction in ascomycetes?

• A. Ascus
• B. Conidiophore
• C. Basidium
• D. Sporangium

Answer: (A)

Verified step by step guidance

1. Understand the context: Ascomycetes are a group of fungi known for their unique reproductive structures. They are part of the phylum Ascomycota.
2. Identify the key term: The term 'sexual reproduction' in ascomycetes refers to the process where two compatible nuclei fuse to form a diploid zygote, which then undergoes meiosis.
3. Recognize the structure: The 'ascus' is the sac-like structure where the sexual spores, called ascospores, are formed in ascomycetes. This is the site of meiosis and subsequent spore development.
4. Differentiate from other structures: A 'conidiophore' is involved in asexual reproduction, producing conidia (asexual spores). A 'basidium' is the reproductive structure in basidiomycetes, not ascomycetes. A 'sporangium' is a structure found in other fungi and plants, not specifically related to ascomycetes' sexual reproduction.
5. Conclude with the correct structure: Based on the understanding of these structures, the 'ascus' is the correct answer as it is responsible for sexual reproduction in ascomycetes.