Practice question

Domain Eukarya encompasses all organisms possessing true membrane-bound nucleus enclosing linear chromosomes complexed with histones, plus endomembrane system including endoplasmic reticulum, Golgi, and mitochondria or derived hydrogenosomes. Membership includes diverse protistan lineages, green plants deriving from primary endosymbiosis of cyanobacterium, multicellular fungi with absorptive nutrition and chitinous walls, and animals with collagen, nervous systems, and embryogenesis. Unified by eukaryotic signature proteins such as ubiquitin, spliceosome, and actin-tubulin cytoskeleton, molecular phylogeny places protists as grade leading to other kingdoms, yet all belong within single eukaryotic domain distinct from prokaryotes.