EasyBiologyHigh School (11–12)Heredity and Evolution › Principles of Inheritance and VariationNumericalAP A-Level IB

Two healthy people are both carriers of the autosomal recessive allele for beta thalassaemia…

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Two healthy people are both carriers of the autosomal recessive allele for beta thalassaemia. They have children.

What is the chance that a child has thalassaemia?

What is the chance that a child is a carrier?

Among $12$ children, how many are expected to have thalassaemia?

Need a reminder? The key ideaShow

In an autosomal recessive disorder, two carriers (Aa × Aa) have children in the ratio 1 AA : 2 Aa : 1 aa. The chance of an affected child is $\tfrac{1}{4}$ , of a carrier $\tfrac{1}{2}$ , and each child is an independent event. Thalassaemia is a problem of the amount of globin, and sickle-cell anaemia is a problem of one amino acid of the globin.

The worked solution

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Two healthy people are both carriers of the autosomal recessive allele for beta thalassaemia…

The worked solution

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