Which statement correctly defines ‘aerobes’?

• A. Bacteria that require oxygen to grow
• B. Bacteria that use oxygen for cellular respiration
• C. Bacteria that do not require oxygen
• D. A process of mixing air into liquid

Answer: (C)

Aerobes are organisms that require oxygen to grow and to generate energy. Oxygen serves as the final electron acceptor in their cellular respiration, allowing them to efficiently produce ATP. Because of this, statements that describe bacteria using oxygen for respiration fit the definition of aerobes. The idea that aerobes do not need oxygen describes anaerobes, while mixing air into liquid is unrelated to the biological definition. In wastewater contexts, aerobic bacteria are the ones that rely on oxygen to break down organic matter.