Final answer:
Fungi are a kingdom of eukaryotic, heterotrophic organisms with cell walls made of chitin, which distinguishes them from plants. They absorb nutrients from their environment, act as essential decomposers, and include forms such as mushrooms, molds, and yeasts.
Step-by-step explanation:
What is a Fungus?
Fungi are a distinct kingdom within the domain Eukarya that encompasses a wide range of organisms such as molds, mushrooms, and yeasts. Most fungi are multicellular and possess cell walls made of chitin, which differentiates them from plants that have cell walls made of cellulose.
Fungi are eukaryotic organisms that are heterotrophic, meaning they cannot produce their own food through photosynthesis like plants, but instead absorb nutrients from their environment. This they achieve by secreting enzymes that break down complex organic compounds into simpler forms that can be absorbed. Although fungi were once classified with plants, modern molecular studies reveal that they share a closer relationship to animals. Fungi store glycogen, like animals, and possess cell walls containing chitin, which is also found in the exoskeletons of arthropods.
Fungi are essential decomposers in ecosystems, playing a critical role in nutrient cycling by breaking down organic materials. Some fungi are also known for forming symbiotic relationships, and others can be pathogenic to plants and animals, including humans. Representative examples of fungi include the well-known edible mushrooms, yeast used in baking and brewing, black mold often found in damp buildings, and Penicillium notatum, the source of the antibiotic penicillin.