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

Oxygen is transported from the lungs to all parts of the body by haemoglobin in red blood cells, forming oxyhaemoglobin. Once oxygen reaches the body's cells, its primary biological function is to serve as the final electron acceptor in aerobic cellular respiration, the process by which cells break down glucose to release energy in the form of ATP.

The overall equation for aerobic respiration is:

\[ \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{energy (ATP)} \]

Without oxygen, cells cannot carry out aerobic respiration efficiently and must rely on anaerobic respiration, which yields far less ATP. The energy released is used for all life processes, including growth, movement, active transport, and maintaining body temperature.

The removal of waste products is a function of the excretory system, not a direct use of oxygen. Growth and development of cells depend on the energy that respiration provides, but oxygen is not directly "used for" growth - it is used for respiration, which powers growth. The formation of carboxyhaemoglobin (not "carboxyl") occurs when carbon monoxide binds to haemoglobin, which is a toxic event, not a normal physiological function of oxygen.

Exam tip: The key phrase is "used for." Oxygen is specifically used in cells for the release of energy from food (aerobic respiration). Other processes like growth are downstream consequences of that energy release.