In which domain(s) of life are microorganisms represented?

• A. Only Eukarya
• B. Only Bacteria and Archaea
• C. Only Bacteria
• D. Bacteria, Archaea, and Eukarya

Answer: (D)

Verified step by step guidance

1. Understand the three domains of life: Bacteria, Archaea, and Eukarya. These domains classify all living organisms based on genetic and cellular characteristics.
2. Recall that microorganisms are organisms that are typically microscopic and include bacteria, archaea, and some eukaryotes such as protists and fungi.
3. Recognize that Bacteria and Archaea are both domains composed entirely of microorganisms, as all their members are microscopic prokaryotes.
4. Note that the domain Eukarya includes many multicellular organisms, but also contains microorganisms such as unicellular protists and some fungi.
5. Conclude that microorganisms are represented in all three domains: Bacteria, Archaea, and Eukarya, because each domain contains microscopic life forms.