Aerobic respiration, occurring in the presence of oxygen, releases a significantly greater amount of energy compared to anaerobic respiration. It involves the breakdown of pyruvate in the mitochondria, producing carbon dioxide and water.

Anaerobic respiration is a process where the breakdown of pyruvate occurs in the absence of air (oxygen). It takes place in organisms like yeast during fermentation.

The breakdown of glucose into pyruvate takes place in the cytoplasm of cells.

The large intestine absorbs water from unabsorbed food, making the material more solid. The remaining waste is expelled through the anus, and the exit is regulated by the anal sphincter.

The villi in the small intestine are richly supplied with blood vessels. These vessels transport the absorbed nutrients to every cell of the body, where they are utilized for energy, tissue building, and repair.