Which characteristic is indicative of the kingdom Fungi?

The characteristic that indicates membership in the kingdom Fungi is the presence of cell walls made of chitin. In fungi, chitin is a key component of their cell walls, which provides structural support and rigidity. This is distinct from plants, which have cell walls composed of cellulose.

Fungi exhibit a wide variety of forms, including single-celled organisms like yeasts as well as multicellular forms like molds and mushrooms. Therefore, the notion that fungi are exclusively multicellular is incorrect because the kingdom encompasses both types. Additionally, fungi are heterotrophic organisms that obtain their nutrients by absorbing organic material, rather than through photosynthesis, which is a process associated with plants and some protists. Lastly, fungi do not possess the ability to move independently; they are generally stationary organisms. Therefore, the defining feature of having cell walls made of chitin is what clearly identifies fungi as a separate kingdom within the larger framework of biological classification.