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3.3 Inheritance

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Question 3
F

Cystic fibrosis is an inherited disorder caused by a recessive allele, fff. The dominant allele is FFF.

The Figure shows a family pedigree for cystic fibrosis.

Figure

image

a.

Give the number of people in the family pedigree who have cystic fibrosis.

[1]
b.

Explain how the family pedigree shows that cystic fibrosis is caused by a recessive allele.

[2]
c.

Give the genotype of person 4. Explain your answer.

[2]
d.

Persons 4 and 6 are planning to have another child.

Use a Punnett square to calculate the probability that their next child will have cystic fibrosis.

[3]
Markscheme

3.3 Inheritance Questions

  1. GCSE
  2. /Biology
  3. /3.3 Inheritance

43 exam-style questions on Edexcel GCSE Biology 3.3 Inheritance, covering 3.3.1 Gregor Mendel and the basis of genetics, 3.3.2 Alleles and inherited characteristics, 3.3.3 Monohybrid inheritance, 3.3.4 Determination of sex at fertilisation, 3.3.5 Outcomes from monohybrid crosses, 3.3.6 Inheritance of ABO blood groups, 3.3.7 Inheritance of sex-linked disorders, and 3.3.8 Multiple genes and phenotypic features. Each one has a worked solution and a mark scheme showing where the marks go.

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