Final answer:
Yeasts are unicellular fungi, and molds are multicellular fungi. Molds consist of long filaments and have diverse roles, from decomposition to medical applications. The classification can be complex, with some previously considered fungi, like water molds, being reclassified based on cellular differences.
Step-by-step explanation:
Yeasts are unicellular fungi, and molds are multicellular fungi. These organisms are classified in the Fungus Kingdom, which includes a diverse array of species such as molds, mushrooms, and yeasts. Molds, specifically, are composed of long filaments called hyphae and can form visible colonies. These multicellular fungi are commonly found in various environments and play essential roles in decomposing organic matter. Some molds can have negative impacts, causing allergies or producing mycotoxins, while others have beneficial uses in medicine, like the creation of antibiotics.
It's important to note that not all organisms that were once thought to be fungi are classified as such today. For example, öomycetes, also known as water molds, have cell walls of cellulose and are typically diploid, which distinguishes them from true fungi that have chitinous cell walls and are usually haploid. Despite their name, water molds are not classified within the fungal kingdom.