Which of the following is incorrect for ascomycetes

The correct option is "coenocytic mycelium".

Let us analyze the characteristics of Ascomycetes (commonly known as sac fungi) step-by-step to understand why this option is incorrect for them:

1. Structure of Mycelium:
Ascomycetes have a septate and branched mycelium. The hyphae are divided into cells by internal cross-walls called septa. These septa have pores that allow cytoplasm and sometimes even nuclei to pass between cells.
A coenocytic mycelium, on the other hand, is multinucleate and lacks septa (aseptate), meaning the cytoplasm is continuous. Coenocytic mycelium is a characteristic feature of another class of fungi called Phycomycetes (such as Mucor, Rhizopus, and Albugo), not Ascomycetes. Therefore, the statement "coenocytic mycelium" is incorrect for Ascomycetes.

2. Evaluating the other statements:
- "They are unicellular as well as multicellular": This is correct. Most Ascomycetes are multicellular (e.g., Penicillium), but some are unicellular (e.g., Yeast / Saccharomyces).
- "Neurospora, Claviceps and yeast belong to Ascomycota": This is correct. All three are classic examples of the phylum Ascomycota. Neurospora is extensively used in biochemical and genetic work, Claviceps causes ergot of rye, and yeast is widely used in baking and brewing.
- "They are parasitic, saprophytic or coprophilous": This is correct. Ascomycetes exhibit diverse modes of nutrition. They can be decomposers (saprophytic), pathogens/parasites on plants and animals (parasitic), or grow on dung (coprophilous).

Since the question asks for the incorrect statement regarding ascomycetes, the correct choice is "coenocytic mycelium".