The process that uses oxygen in plants, algae, and animals is cellular respiration.

Here's why:

* Cellular respiration is the process by which organisms break down glucose (sugar) in the presence of oxygen to release energy (ATP) for their cells.

* This energy is used for all the essential life processes, like growth, movement, and maintaining body temperature.

* The chemical equation for cellular respiration is:

C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy (ATP)

This shows that glucose (C6H12O6) is combined with oxygen (O2) to produce carbon dioxide (CO2), water (H2O), and energy (ATP).

Let me know if you have any other questions!