Final answer:
Fungi are single-cell organisms that include molds, mildews, and yeasts. They can be unicellular or multicellular and have various environmental roles, from decomposition to pharmaceutical production and food spoilage.
Step-by-step explanation:
Single-cell organisms that grow in irregular masses and include molds, mildews, and yeasts are known as fungi.
Fungi can be either unicellular or multicellular organisms, and they have a variety of roles in the environment.
Some common examples of fungi include bread molds (a fungal group), Glomeromycota (most of which associate with plants), and yeasts, which are atypical members of generally multicellular or colonial fungal groups, most being cup fungi (Ascomycota).
Additionally, some fungi are noteworthy to microbiologists because of their importance in decomposition, their contributions to pharmaceuticals such as penicillin, and their potential to cause disease or spoil food.