Florida Biology EOC Practice Test

Which kingdom is composed of unicellular, prokaryotic organisms that differ from bacteria in their genetics and membrane structures?

1. Animalia

2. Archaebacteria

3. Bacteria

4. Protista

The correct answer is: Animalia

The kingdom that is composed of unicellular, prokaryotic organisms differing from bacteria in their genetics and membrane structures is Archaebacteria. This kingdom includes organisms known as archaea, which are distinct from eubacteria due to their unique biochemical and genetic properties. Archaea can survive in extreme conditions, such as high temperatures, salinity, or acidity, which reflects their evolutionary adaptation. Their cell membranes contain ether linkages as opposed to the ester linkages found in bacteria, contributing to their resilience in harsh environments. Genetically, archaea have more similarities to eukaryotes than to bacteria, particularly in their RNA polymerases and ribosomal RNA. In contrast, Animalia is a kingdom that comprises multicellular, eukaryotic organisms, which fundamentally differs from prokaryotic organisms like archaea. Bacteria are also unicellular and prokaryotic but do not possess the distinct genetic and membrane characteristics that define archaea. Protista includes a diverse group of eukaryotic organisms, which also makes it distinct from prokaryotic kingdoms. Thus, Archaebacteria is indeed the right classification for this unique group of organisms.