Ameoba is a unicellular organism. It depends on simple diffusion of gases for breathing. The exchange of gases in Amoeba takes place through its cell membrane. Since it lives in water, the oxygen from water diffuses into the body of Amoeba through its cell membrane. This oxygen is used for respiration inside the Amoeba cell. The process of respiration continuously produces carbon dioxide that diffuses out through the membrane of Amoeba into the surrounding water.
Respiration in Amoeba is aerobic.