Organisms that require oxygen for survival are called ______; organisms that do not require oxygen are ______.

Organisms that require oxygen for survival are called ______; organisms that do not require oxygen are ______.

• A. Capnophiles, Barophiles
• B. Aerobes, Anaerobes
• C. Facultative anaerobes, Microaerophiles
• D. Anaerobes, Aerobes

Answer: (B)

Oxygen availability dictates how organisms generate energy. Those that require oxygen for survival rely on aerobic respiration, using oxygen as the final electron acceptor to efficiently produce ATP; they cannot thrive without it. Those that do not require oxygen rely on anaerobic methods such as fermentation or anaerobic respiration with alternative electron acceptors, and many are harmed by oxygen exposure. This pairing—aerobes for organisms that need oxygen and anaerobes for those that do not—best fits the description. Other terms like facultative anaerobes (can grow with or without oxygen) or microaerophiles (need only a small amount of oxygen) do not match the strict requirement implied in the statement.

Oxygen availability dictates how organisms generate energy. Those that require oxygen for survival rely on aerobic respiration, using oxygen as the final electron acceptor to efficiently produce ATP; they cannot thrive without it. Those that do not require oxygen rely on anaerobic methods such as fermentation or anaerobic respiration with alternative electron acceptors, and many are harmed by oxygen exposure. This pairing—aerobes for organisms that need oxygen and anaerobes for those that do not—best fits the description. Other terms like facultative anaerobes (can grow with or without oxygen) or microaerophiles (need only a small amount of oxygen) do not match the strict requirement implied in the statement.