Which domain tends to be extremophiles?

• A. Bacteria
• B. Archaea
• C. Eukarya
• D. Protista

Answer: (B)

Extremophiles are organisms that grow best in conditions that are extreme for most life. Among the three domains of life, Archaea stand out as home to many such organisms. You’ll find thermophiles that love scorching heat in hydrothermal vents and hot springs, halophiles thriving in hypersaline lakes, and acidophiles in acidic environments. Their biochemistry helps them cope with these stresses—ether-linked membrane lipids with unusual isoprenoid structures, enzymes that stay stable and functional at high temperatures or salinity, and often anaerobic metabolisms like methanogenesis. This combination of diverse extreme adaptations is why Archaea are most strongly associated with extremophiles, making them the best answer. While some bacteria and certain eukaryotes can tolerate harsh conditions, the domain classically linked to extremophiles is Archaea.