In amoeba respiration takes place through its cell membrane also called the plasma membrane. Amoeba gets oxygen gas dissolved in surrounding water through its plasma membrane by the process of diffusion. The oxygen gas diffused inside the body is used up by the amoeba. In the body, the oxygen gas absorbed is used to break down the complex food material into simple molecules. During these metabolic reactions in the body of amoeba, the oxygen gas is converted into carbon dioxide gas. The carbon dioxide gas is also liberated in the surrounding water through the same process of diffusion.
Since amoeba needs oxygen for respiration, the type of respiration is aerobic respiration.
The notable
hardness of bone is attributed to the presence of inorganic hydroxyapatites.
Due to the calcium salts deposited in it, resulting to the hardness. The
abnormal hardness of bone, which allows it
to resist the compression.