A Level Biology Practice Exam

What are prokaryotic microorganisms that are distinct from bacteria called?

1. Eukarya

2. Archaea

3. Viruses

4. Protozoa

The correct answer is: Archaea

The correct answer is Archaea. Archaea are a unique group of prokaryotic microorganisms that are distinctly different from bacteria. While both Archaea and bacteria are classified as prokaryotes, Archaea possess unique biochemical and genetic traits that set them apart. For example, the composition of their cell membranes is different, as they have ether-linked lipids rather than the ester-linked lipids found in bacterial membranes. Additionally, their ribosomal RNA sequences, as well as other genetic characteristics, show substantial differences from those of bacteria. Eukarya refers to organisms that have eukaryotic cells, which contain a nucleus and organelles, and include animals, plants, fungi, and protists. Viruses, while microscopic and sometimes studied in biology, are not classified as living organisms and are fundamentally different from bacteria and Archaea. Protozoa are eukaryotic organisms, typically single-celled, that can be mobile; they fall within the Eukarya domain and are not prokaryotic like Archaea or bacteria. Therefore, the distinction of Archaea as a separate domain of life highlights their unique characteristics separate from those of bacteria.