Question

A sigmoid curve is obtained when the percentage saturation of haemoglobin (Hb) with oxygen is plotted against the \[\ce{PO2}\] as indicated below: 

Options

• The curve shifts to the right side due to an increased affinity of \[\ce{O2}\] with haemoglobin.

• Curve shifts to the left side due to increased affinity of \[\ce{O2}\] with haemoglobin.

• The curve will not shift either to the left or right.

• The curve becomes a straight line instead of a sigmoidal.

Answer 1

Curve shifts to the left side due to increased affinity of \[\ce{O2}\] with haemoglobin.

Explanation:

Reduced oxygen affinity for haemoglobin is indicated by a right-side shift of the oxygen dissociation curve. As a result, the curve swings to the right and the per cent saturation of haemoglobin with oxygen decreases.