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Cystic fibrosis is a recessive genetic disorder - Edexcel - GCSE Biology - Question 3 - 2018 - Paper 1
Question 3
Cystic fibrosis is a recessive genetic disorder. The pedigree chart shows the inheritance of cystic fibrosis in a family. The pedigree chart shows how cystic fibros... show full transcript
Worked Solution & Example Answer:Cystic fibrosis is a recessive genetic disorder - Edexcel - GCSE Biology - Question 3 - 2018 - Paper 1
Step 1
Explain how the pedigree chart shows that cystic fibrosis is a recessive genetic disorder.
Answer
In the pedigree chart, Rob and Jane, both of whom do not display cystic fibrosis, produced offspring, including Leon, who does have the disorder. This suggests that both parents are likely heterozygous carriers of the cystic fibrosis allele. For Leon to have cystic fibrosis, he must inherit two recessive alleles, confirming the recessive inheritance pattern of the disorder.
Step 2