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Inheritance and genetic crosses

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Question 18

Albinism is an inherited condition that affects the production of melanin in the skin and hair.

Albinism is caused by a recessive allele (aaa). The dominant allele for normal pigmentation is (AAA).

Figure 1 shows the inheritance of albinism in one family.

Pedigree chart showing the inheritance of albinism. Parent 1 is Male A, represented by a half-shaded square indicating he is heterozygous (Aa). He mates with Parent 2, Female B, represented by an unshaded circle indicating she is unaffected. They have three children: Child 1 is an affected female (solid shaded circle, genotype aa), Child 2 is an unaffected male (unshaded square), and Child 3 is a heterozygous female (half-shaded circle, genotype Aa).

State and explain the genotype of Female B.

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Inheritance and genetic crosses Questions

  1. GCSE
  2. /Biology
  3. /Inheritance and genetic crosses