Why are blue green algae prokaryotic while other algae (green, brown, red) are not?

Question

this is for zoology :)

Answer 1

Prokaryotic, blue green algae is unicellular

Eukaryotic, green, brown, red are multicellular

Answer 2

Algae is a name applied to various organisms which don't happen to form a natural group.  There's no particular relationship between blue-green algae and others.

Answer 3

Prokaryotes are organisms that lack membrane-bound organelles, such as the nucleus.  Conveniently, they all happen to be single-celled, but this is less important and not particularly helpful.  We generally refer to prokaryotes as "bacteria," and the "blue-green algae" are simply a subset of bacteria that happen to be photosynthetic, but the name is unfortunate because the use of ther word "algae" suggests a close relationship between these bacteria and other algaes that doesn't exist.

True algaes are all eukaryotes (i.e., they have membrane-bound organelles such as the nucleus).  Contrary to the earlier response, they are *not* all multicellular, but many of them are.  There are plenty that are unicellular of course.  Anyway, by virtue of the fact that they have membrane-bound organelles, they're all eukaryotes and thus more closely related to you and me than they are to bacteria or blue-green algae.