Answer:
1) Organisms in this domain can be unicellular or multicellular - Eukarya
2) Organisms in this domain are unicellular and are often found in extreme environments - Archaea
3) Organisms in this domain have cells that contain a nucleus - Eukarya
Explanation:
All living organisms were classified into a large group consisting of three types of organisms called DOMAIN. It is the highest taxonomic rank of organisms. The three domains that life was classified into are: Archaea, Bacteria and Eukarya.
The domain Archaea contains organisms that are unicellular and prokaryotic i.e. they do not have a membrane-bound nucleus. The organisms in this domain are characterized by their ability to survive in harsh environmental conditions e.g hot temperatures etc
The domain Bacteria also consists of unicellular and prokaryotic organisms. They contain cell walls in their cells made up of peptidoglycan unlike domain Archaea and Eukarya.
The domain Eukarya consists of organisms that are both unicellular and multicellular and strictly eukaryotic i.e. possess a membrane bound nucleus that houses their genetic material. They are divided into Kingdoms: Protista, Plantae, Animalia and Fungi.