A monophyletic group is one in which all members have a single common ancestor. Protista is paraphyletic, however, so it is not really a kingdom. The major protist phyla have been grouped into seven...

A monophyletic group is one in which all members have a single common ancestor. Protista is paraphyletic, however, so it is not really a kingdom. The major protist phyla have been grouped into seven major monophyletic groups. All protists have plasma membranes, but other cell-surface components, such as deposited extracellular material (ECM), are highly variable. Protists mainly use fl agella or pseudopodial movement to propel themselves. Phototrophic protists carry out photosynthesis; phagotrophs ingest food particles; and osmotrophs ingest dissolved nutrients. Sexual reproduction is common, but asexual reproduction also occurs in many groups. Multicellular organisms likely arose from colonial protists.

■ Why is Kingdom Protista considered to be a paraphyletic group?

■ What would be the advantage of movement by pseudopodia?