a. Copy the following table to summarise some differences between collagen and haemoglobin.

Collagen	Haemoglobin

Use the following to guide you.

Row 1: State whether globular or fibrous.

Row 2: State whether entirely helical or partly helical.

Row 3: State the type of helix.

Row 4: State whether a prosthetic group is present or absent.

Row 5: State whether soluble in water or insoluble in water.

b. State one way in which the structure of haemoglobin is related to its function.

c. Haemoglobin possesses a quaternary structure. What does this mean?

d. Name the five elements found in haemoglobin.