Haemoglobin and oxygen transportAQA A-Level Biology: Mind map

Exam questions on Haemoglobin and oxygen transport

1. Haemoglobin is carried inside red blood cells. A student is studying the structure of human haemoglobin and how it takes up oxygen in the lungs. She notes that the oxyhaemoglobin dissociation curve for haemoglobin is S-shaped, with a shallow start and then a steep rise as the partial pressure of oxygen increases.
   Explain why the oxyhaemoglobin dissociation curve is S-shaped, with a shallow start and then a steep rise.2 marks
2. During vigorous exercise, the muscle cells of a runner respire rapidly and release large amounts of carbon dioxide. This lowers the pH of the blood in the muscle capillaries. A sports scientist is investigating how this affects the way haemoglobin loads and unloads oxygen.
   Explain how the effect of carbon dioxide on haemoglobin benefits the exercising muscle.2 marks
3. In the placenta, oxygen passes from the mother's blood to the blood of the fetus. Adult haemoglobin is 50% saturated at a partial pressure of oxygen of 3.5 kPa, whereas fetal haemoglobin is 50% saturated at 2.4 kPa. At a partial pressure of oxygen of 4 kPa, similar to that in the placenta, adult haemoglobin is about 59% saturated and fetal haemoglobin is about 80% saturated. After birth, fetal haemoglobin is gradually replaced by adult haemoglobin over the first few months of life.
   Use the information to explain how fetal haemoglobin allows the fetus to obtain oxygen from its mother's blood.3 marks