NEET BIOLOGY

Detailed explanation-1: -They are animal-like because they are heterotrophs, and are capable of moving. Although protozoa are not animals, they are thought to be the ancestors of animals.

Detailed explanation-2: -Answer and Explanation: Biologists believe that a primitive choanoflagellate protist is an ancestor of all animals because they are the first in the tree of evolution to display features that are characteristic of animals.

Detailed explanation-3: -All true animals-members of the kingdom Animalia-are eukaryotic multicellular organisms that share a single common evolutionary ancestor (Fig. 3.4). This last common ancestor was likely a single-celled organism similar to modern day choanoflagellates.

Detailed explanation-4: -Often, protozoa is just an informal term for unicellular, heterotrophic protists. The name protozoa ("first animals") is misleading, since they are not animals (with the possible exception of the Myxozoa).

Detailed explanation-5: -Historically, protozoans were regarded as “one-celled animals", because they often possess animal-like behaviours, such as motility and predation, and lack a cell wall, as found in plants and many algae.