Final answer:
Organisms in the domain Archaea have DNA that is not in a nucleus, unlike organisms in the Eukarya domain, making them prokaryotic and often extremophiles. option b is correct.
Step-by-step explanation:
Organisms in the domain Archaea differ from those in the domain Eukarya primarily because Archaea have DNA that is not enclosed in a nucleus. More specifically, the correct answer from the options given is 'b. archae have dna that is not in a nucleus'. Unlike Eukarya, Archaea are unicellular and prokaryotic. This means that their cells lack a nucleus and other membrane-bound organelles such as mitochondria.
Furthermore, Archaea have unique properties that separate them from Bacteria, the other prokaryotic domain. While both Archaea and Bacteria have a single piece of circular DNA in the nucleoid area of the cell and most have a cell wall outside the plasma membrane, their membrane structure and rRNA are significantly different.
Additionally, many Archaea are extremophiles, living in harsh environments, which supports the idea that they could be descendants of some of the most ancient life forms on Earth.
One of the key distinctions between organisms in the domain Archaea and those in the domain Eukarya is the organization of genetic material. Archaea have a type of genetic material similar to DNA, but their DNA is not enclosed within a membrane-bound nucleus, unlike organisms in the domain Eukarya. Organisms in the domain Eukarya, which includes plants, animals, fungi, and protists, have their genetic material contained within a membrane-bound nucleus. The lack of a nucleus is a fundamental feature that sets Archaea apart from Eukarya.