Question: What is the main function of a red blood cell?

Robert Hampson answered on 11 Nov 2014:

Red blood cells contain haemoglobin which is a large protein containing iron. Oxygen binds well to haemoglobin when there is a lot around (like in your lungs) but is easily released when there isn’t much oxygen around (like in the rest of your body). Red blood cells therefore deliver oxygen to your body from your lungs. They also have other minor functions but that is the main one.