Q: a: recent work in classification of life on earth has shown that what were once called prokaryotes are much more diverse than ever suspected. the prokaryotae are now divided into two domains, the eubacteria and the archaeabacteria, as different from each other as either is from the eukaryota. one organism, the blue-green algae or cyanobacteria, has left a fossil record that dates back nearly 3.5 billion years and is among the oldest fossils known. these blue-green algae had cell walls and were photosynthetic. a few hundred years ago, this organism was classified as a plant, then as a protist. today it is classified in the eubacteria because it a) is prokaryotic. b) is photosynthetic. c) is the ancestor of land plants. d) has cell walls and chloroplasts.

A) is prokaryotic

Explanation:

Cyanobacteria are prokaryotic organisms, they lack a defined nucleus and their DNA is coiled up in a region of the cytoplasm (nucleoid), therefore they belong to the Eubacteria domain. These bacteria are photosynthetic (they take energy from sunlight). Nevertheless, they are very basic cells and far from being related to more complex eukaryotic organisms that also perform photosynthesis.

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parasites can detrimentally affect their host, but also must not allow their host to die before they can complete their life cycle. some parasites have complex life cycles with many different hosts, and have had to find ways of persisting in many different environments during the change from one host to another. ectoparasites live outside the body of the host, and can more easily  disperse, but are  more exposed to predators, parasites, parasitoids. endoparasites live inside the body of the host, and are therefore protected from the outside environment. but they can be  attacked by the host's immune system. they have therefore developed  mechanisms for dispersal such as  complex life cycles.