Transport of gases in the bloodEdexcel A-Level Biology B: Flashcards

What these 15 flashcards ask

What is the structure of adult haemoglobin?
What does a haem group contain?
How many oxygen molecules can one haemoglobin carry?
Why is the oxygen dissociation curve S-shaped?
What is plotted on an oxygen dissociation curve?
What does a curve shifted to the left show?
What is the Bohr effect?
How does CO₂ lower the pH of the blood?
Which enzyme converts CO₂ and water to carbonic acid in red blood cells?
Why is the Bohr effect useful in exercising muscle?
How many polypeptide chains does myoglobin have?
Where does the myoglobin curve lie compared with haemoglobin?
What is the function of myoglobin?
Why does fetal haemoglobin have a higher oxygen affinity?
Where does the fetal haemoglobin curve lie?

Exam questions on Transport of gases in the blood

Adult haemoglobin is a protein made of four polypeptide chains. Each chain contains a haem group with one iron(II) ion at its centre. Experiments show that the oxygen dissociation curve of haemoglobin is S-shaped, because the first oxygen molecule binds slowly but later molecules bind more easily.
Explain why the oxygen dissociation curve of haemoglobin is S-shaped.2 marks
During vigorous exercise the muscle cells of an athlete respire rapidly. The partial pressure of carbon dioxide in the muscle capillaries rises and the pH of the blood in the capillaries falls. The oxygen dissociation curve of the haemoglobin in these capillaries changes position.
Explain how the rise in carbon dioxide concentration in the muscle capillaries causes oxygen to be released from haemoglobin more readily.2 marks
Seals dive for long periods without breathing. Their muscles contain a very high concentration of myoglobin. Myoglobin is a single polypeptide with one haem group. At a partial pressure of oxygen of 2 kPa, myoglobin is more than 80% saturated with oxygen, whereas adult haemoglobin is only about 25% saturated.
Compare the structure and function of myoglobin with those of adult haemoglobin.3 marks

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).