An organism that requires oxygen to survive is called what?

• A. Aerobic
• B. Anaerobic
• C. Eukaryote
• D. Pathogen

Answer: (A)

Oxygen is required for efficient cellular energy production in many organisms, so an organism that needs oxygen to survive is described as aerobic. In aerobic respiration, glucose is fully oxidized through glycolysis, the citric acid cycle, and the electron transport chain, with oxygen acting as the final electron acceptor. This chain builds a large amount of ATP, meeting the energy demands of the organism. When oxygen isn’t available, many organisms can’t produce as much ATP through aerobic pathways and may rely on fermentation or anaerobic respiration instead, which yield far less energy. The other terms describe different ideas: a eukaryote is a cell type with a nucleus, and a pathogen is a disease-causing agent.