(a(i))[1]
Give the name of the blood vessel shown as Z in Fig. 5.1.
(a(ii))[2]
The system is referred to as a double circulatory system. Describe what is meant by a double circulation.
(a(iii))[3]
Explain how the structure of the human heart is adapted for it to act as the pump in a double circulatory system.
(b)[4]
Some people have a heart defect called a 'hole in the heart', as shown in Fig. 5.2. People with a hole in their heart may feel muscle pain and become tired very quickly when they exercise. Explain why this happens.