Which group of unicellular prokaryotes is most commonly found living in extreme environments such as volcanic ash?

• A. Cyanobacteria
• B. Archaea
• C. Proteobacteria
• D. Spirochetes

Answer: (B)

Verified step by step guidance

1. Understand the classification of unicellular prokaryotes: Prokaryotes are divided mainly into Bacteria and Archaea. Both groups consist of unicellular organisms without a nucleus.
2. Recall the environmental preferences of each group: Cyanobacteria, Proteobacteria, and Spirochetes are types of Bacteria, which are commonly found in a variety of environments but not typically extreme ones.
3. Recognize that Archaea are known for their ability to thrive in extreme environments, such as high temperature, acidity, salinity, or volcanic ash, due to their unique cell membrane and metabolic adaptations.
4. Identify that volcanic ash represents an extreme environment characterized by high temperature and possibly acidic conditions, which are habitats where Archaea are most commonly found.
5. Conclude that among the given options, Archaea is the group of unicellular prokaryotes most commonly found living in extreme environments such as volcanic ash.