Have a go at this question about sickle cell anaemia. Write out your answers on paper or a printout of this page and fill it out-
Check your answers here

Sickle cell anaemia is a condition where the haemoglobin in the red blood cells can no longer carry oxygen efficiently at low oxygen concentrations. Heterozygous individuals show some symptoms of anaemia and appear to be at a potential disadvantage, but they have some resistance to malaria.

In Fig. 2.1, A shows the distribution of the malarial parasite in parts of East Africa below 1500 metres, whilst B shows the area in which more than 15% of the adults in the population are heterozygous for the sickle cell condition.

Fig. 2.1

1. With reference to Fig. 2.1,

   1. describe, with reasons, the distribution of the sickle cell heterozygotes;

      [3]

   2. explain why this distribution of heterozygote individuals has been shown in this area for many generations.

      [3]

2. If the inhabitants of the settlement indicated on Fig. 2.1 were moved to an area where malaria did not exist, suggest what might happen to the population of heterozygotes in future generations. Explain your answer.

   [3]