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Cystic fibrosis is caused by a recessive allele - Scottish Highers Human Biology - Question 14 - 2023
Question 14
Cystic fibrosis is caused by a recessive allele. The diagram shows the inheritance of cystic fibrosis in three generations of a family. Key ■ affected male □ unaff... show full transcript
Worked Solution & Example Answer:Cystic fibrosis is caused by a recessive allele - Scottish Highers Human Biology - Question 14 - 2023
Step 1
Which individual confirms that cystic fibrosis is not a sex-linked condition?
Answer
To determine that cystic fibrosis is not a sex-linked condition, we need to find an affected individual who demonstrates that the allele responsible for cystic fibrosis can be passed from one sex to another.
In the family tree provided, individual 'A' (the affected male) has an unaffected mother (individual 'B', who is a carrier of the recessive allele) and can still pass the cystic fibrosis allele to his female offspring, such as individual 'C' (an affected female). This ability for the affected male to pass on the trait to both male and female children is indicative that the condition is inherited in an autosomal manner, rather than being sex-linked.
Therefore, individual 'A' confirms that cystic fibrosis is not a sex-linked condition.