Resting muscle has a lower respiration rate than active muscle. The graph shows the oxygen dissociation curves for haemoglobin at carbon dioxide concentrations that are found in a resting muscle and an active muscle.

P and Q are at the partial pressures of oxygen found in the lungs.

R and S are at the partial pressures of oxygen found in either a resting muscle or an active muscle.

Which statements are correct?

1) The % saturation at P minus the % saturation at S represents the amount of oxygen delivered to a resting muscle.
2) The % saturation at Q represents the amount of oxygen carried to an active muscle.
3) The % saturation at R represents the amount of oxygen required by a resting muscle.
4) The % saturation at P minus the % saturation at Q represents the amount of oxygen delivered to an active muscle.
5) The % saturation at Q minus the % saturation at S represents the amount of oxygen delivered to a resting muscle.