What type of things belong in the Protista kingdom?

Answer 1

Protists are unicellular eukaryotes, So they have membrane-bound organelles similar to animal cells and are in general larger than bacterial or archaea cells. Probably the mos famous protist is the Amoeba, but many many others exist.

However, the term is being used less in favor of recognizing the diversity of these organisms. The term is still commonly used to refer to unicellular eukaryotes, but may not always be considered a proper "kingdom" comparable to plantae or animalia.

Answer 2

The Protista kingdom is a diverse group of organisms that includes single-celled organisms such as protozoa, algae, and slime molds. These organisms may share characteristics with both plants and animals, but do not fit neatly into either category. They can be found in various habitats, including freshwater and marine environments.