3.1.2: Haemoglobin

Question 1

What is myoglobin?

Answer 1

A protein that has a very high affinity for oxygen, acting as an oxygen store in animals like lugworms, whales, and human foetuses.

Myoglobin does not dissociate oxygen until nearly all oxygen has been used up in cells.

Question 2

How does myoglobin differ from haemoglobin in terms of oxygen transport?

Answer 2

Myoglobin has a higher affinity for oxygen at low partial pressures compared to haemoglobin.

This allows myoglobin to hold onto oxygen until it is critically needed.

Question 3

What adaptations do llamas have for high altitudes?

Answer 3

Llamas have a type of haemoglobin with a higher affinity for oxygen to compensate for lower atmospheric pressure and oxygen partial pressure.

This adaptation allows them to effectively load oxygen despite lower availability.

Question 4

What are the three ways carbon dioxide is transported in the blood?

Answer 4

• Dissolved in the blood plasma
• As haemoglobinic acid
• As hydrogen carbonate ions in the cytoplasm of red blood cells

Almost 85% of carbon dioxide is transported as hydrogen carbonate ions.

Question 5

What role does carbonic anhydrase play in carbon dioxide transport?

Answer 5

It catalyses the reversible reaction between water and carbon dioxide to form hydrogen ions and hydrogen carbonate ions in red blood cells.

This enzyme is crucial for the majority of carbon dioxide transport in the blood.

Question 6

What happens to carbon dioxide when it reacts with amino acids in haemoglobin?

Answer 6

It forms haemoglobinic acid through a reversible reaction.

This process is part of how carbon dioxide is transported in the blood.

Question 7

What is the significance of oxygen partial pressure in myoglobin function?

Answer 7

Myoglobin maintains a high affinity for oxygen even at very low partial pressures, allowing it to function effectively as an oxygen store.

This property is important for survival in low-oxygen environments.

Question 8

What is considered a normal pH level in the blood?

Answer 8

pH 7.4

Deviations from this level can indicate conditions like acidosis or alkalosis.

Question 9

Fill in the blank: Llamas have a type of haemoglobin with a higher affinity for oxygen to adapt to _______.

Answer 9

[low partial pressure of oxygen].

Question 10

True or False: Myoglobin dissociates oxygen readily at low partial pressures.

Answer 10

False

Myoglobin retains oxygen until it is needed, unlike haemoglobin.