Final answer:
The Kingdom Fungi is composed of heterotrophic organisms such as mushrooms, molds, and yeast that do not perform photosynthesis. Protists are a diverse group divided into animal-like, plant-like, and fungus-like protists, with the latter resembling fungi in nutrition and reproduction, but differing in mobility.
Step-by-step explanation:
The Kingdom Fungi includes both multicellular and unicellular organisms that are heterotrophic, meaning they rely on absorbing nutrients from other living matter. Commonly mistaken as plants due to their immobility and growth in soil, fungi differ significantly as they do not perform photosynthesis. Mushrooms are just one of the reproductive structures within this kingdom, while other fungi manifest as molds, mildews, or yeasts. Yeast, which is important in food production due to its role in fermentation, is a notable unicellular fungus.
Protists, on the other hand, represent a highly diverse group. This kingdom was initially grouped apart due to the complex taxonomic challenges it presented. Protists can be animal-like, plant-like, or fungus-like, with varied traits across the kingdom. For classification, they are divided into groups based on resemblance to other kingdoms, such as animal-like, plant-like, and fungi-like protists.
Fungus-like protists resemble fungi as they are heterotrophs with cell walls and reproduce via spores. Yet, they are different as some have the capability to move at certain life stages. They include slime molds and water molds, which can sometimes be mistaken for fungi due to their similar life strategies and forms.