Final answer:
The two kingdoms containing all unicellular members are Archaea and Bacteria. These are prokaryotic organisms without a nucleus, differing in their cell wall composition and habitats.
Step-by-step explanation:
The question is asking which two kingdoms contain members that are all unicellular. In the classification of living organisms, these kingdoms are known as Archaea and Bacteria. Both of these kingdoms consist entirely of unicellular prokaryotes, organisms that lack a nucleus or any other membrane-bound organelles. Though both are composed of prokaryotic cells, they have significant differences such as their cell wall composition and the environments they inhabit. The domain Archaea includes species that can live in extreme environments, while both domains are capable of asexual reproduction.
Moreover, Ernst Haeckel introduced the kingdom Protista as a group of unicellular eukaryotes which includes organisms like Euglena. However, not all members of the Protista kingdom are unicellular, but many, such as algae and euglenophytes, are. Protista is more diverse and includes both autotrophic and heterotrophic organisms, as well as those able to switch between these nutritional modes.