Haemoglobin Adaptations

Question 1

Describe and explain the oxygen dissociation curves of foetal haemoglobin compared to maternal haemoglobin.

Answer 1

The curve of foetal haemoglobin is to the left of the maternal Hb curve.
—> as foetal Hb has a higher affinity for oxygen than maternal
—> so O2 dissociates from maternal Hb and binds to foetal Hb

Question 2

Describe and explain the oxygen dissociation curve of organisms living in low oxygen levels.

Answer 2

• The curve is shifted to the left.
  —> the organisms need to have Hb with a higher affinity for O2, so more oxygen can bind to Hb at gas exchange surfaces.
  —> as the organisms have a high SA:V ratio so lose heat more quickly, so need to respire much more.

Question 3

Describe and explain the oxygen dissociation curve for organisms living at high altitudes.

Answer 3

• The curve is shifted to the left as there is a low pO2, so the organisms Hb must have a higher affinity for oxygen.
  —> more O2 will bind to the Hb and can be delivered to respiring tissue cells.

Question 4

Describe how small mammals Hb is adapted for survival and why it has to be adapted this way.

Answer 4

• Small mammals have a high SA:V, so lose heat quickly.
• So to maintain a high body temperature, they have a high metabolic rate to generate more heat.
• Also, they are more active so have a higher demand for oxygen, so have Hb with a lower affinity for O2 than human Hb.
• Therefore, the oxygen dissociation curve is shifted to the right and more O2 is dissociated at respiring muscle tissue cells.