The oxygen transported to all parts of the body during blood circulation is used for the

1. Analyze the question The question asks what the oxygen carried by the blood to every part of the body is used for. This is about the role of oxygen in cells.

2. Explain the concept Oxygen is carried from the lungs by haemoglobin in red blood cells (as oxyhaemoglobin). When it reaches the tissues, it is used in aerobic respiration, which takes place in the mitochondria:

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy

Oxygen is needed to break down glucose (food) completely and release usable energy (ATP).

3. Go through the options

• A. Growth and development of cells: Growth depends on nutrients and on the energy released by respiration. Oxygen's direct role is not growth itself.
• B. Removal of waste products: Waste removal is done mainly by excretory organs (kidneys, lungs, skin). Oxygen is not the agent for this.
• C. Release of energy from food: This is correct. Oxygen oxidises food substances (glucose) in respiration to release energy.
• D. Formation of carboxyl haemoglobin: This is a distractor. The correct term is carboxyhaemoglobin, which forms when haemoglobin combines with carbon monoxide (CO), not oxygen. It is harmful, not a use of oxygen.

4. Answer The correct option is C. release of energy from food.

5. Exam tip Whenever you see "oxygen is used for…" in JAMB, think respiration → energy release. Also remember that oxygen combined with haemoglobin gives oxyhaemoglobin, while carbon monoxide gives carboxyhaemoglobin.