Question

Compare respiration and combustion-both involving oxygen of the air.

Answer 1

Respiration is a process whereby living organisms

1. Use oxygen from the air to oxidize food substances mainly glucose, in their body cells.
2. Release energy in the form of heat.
3. Carbon dioxide and water vapour are also produced and released in the exhaled air.

\[\ce{Glucose + \underset{\text{(in air)}}{Oxygen} -> \underset{\text{Exhaled air}}{Carbon dioxide + Water vapour + Energy(heat)}}\]

Combustion or burning, involves oxidation i.e. combination of substances like fuels with oxygen or air generally resulting in the production of heat and light.

\[\ce{Fuel + \underset{\text{(in air)}}{Oxygen} ->Carbon dioxide + Water vapour + \underset{\text{(heat and light)}}{Energy}}\]

Carbon dioxide is released into the air as a result of all burning.