Concept:Oxygen is carried by the blood to body cells, where it is mainly used for cellular respiration.
Explanation:During blood circulation, oxygen binds to haemoglobin in red blood cells to form oxyhaemoglobin.
When blood reaches body tissues, oxygen is released and diffuses into the cells.
Inside the cells, oxygen acts as the final acceptor in the breakdown of glucose.
This process of cellular respiration releases the energy stored in food molecules.
The energy is used for vital activities such as movement, growth, and repair.
Therefore, the oxygen circulated in the blood is primarily used for the release of energy from food.
It is not used for growth, waste removal, or the formation of carboxyl haemoglobin.
Answer:C. release of energy from food