GCSE Edexcel Biology Genetic Diagrams: Cystic fibrosis is a recessive g

Question

Cystic fibrosis is a recessive genetic disorder.
The pedigree chart shows the inheritance of cystic fibrosis in a family.

The chart indicates that:
- Rob and Jane are parents without cystic fibrosis who had children with cystic fibrosis (Leon).
- This implies that both must be carriers of the recessive allele for cystic fibrosis.
- Therefore, both parents must have at least one recessive allele that they pass to their offspring, which is necessary for Leon to express the disorder.

This illustrates the nature of recessive genetic disorders, where both alleles must be recessive for the phenotype to be expressed.

Which genotype is not possible for Leon?
Put a cross (✗) in the box next to your answer.

A  ff
B  FF
C  ff
D  ff

Cystic fibrosis is a recessive genetic disorder - Edexcel - GCSE Biology - Question 3 - 2018 - Paper 1

Worked Solution & Example Answer:Cystic fibrosis is a recessive genetic disorder - Edexcel - GCSE Biology - Question 3 - 2018 - Paper 1

Explain how the pedigree chart shows that cystic fibrosis is a recessive genetic disorder.

Which genotype is not possible for Leon?

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