Sickle cell anaemia is an inherited blood disorder caused by a recessive allele, sss. The dominant allele, SSS, leads to the production of normal, functional hemoglobin. In sickle cell anaemia, red blood cells lose their flexible biconcave shape and become rigid and sickle-shaped. A father who is a carrier (heterozygous) and a mother who is also a carrier (heterozygous) wish to have children.
State the genotypes of both parents, list the possible genotypes of their children, and determine the probability (as a percentage) that a child will inherit sickle cell anaemia.
Suggest why people with sickle cell anaemia suffer from frequent blockages in their blood vessels (vaso-occlusive crises).
Explain why the rate of oxygen delivery to body tissues is significantly reduced in individuals suffering from sickle cell anaemia.
66 exam-style questions on Edexcel IGCSE Biology Inheritance. Each one has a worked solution and a mark scheme showing where the marks go.