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Cystic fibrosis is a genetic condition caused by a recessive allele (f) - OCR Gateway - GCSE Biology - Question 11 - 2019 - Paper 1
Question 11
Cystic fibrosis is a genetic condition caused by a recessive allele (f). Which is the genotype of a person with cystic fibrosis? A. Heterozygous and ff B. Heterozy... show full transcript
Worked Solution & Example Answer:Cystic fibrosis is a genetic condition caused by a recessive allele (f) - OCR Gateway - GCSE Biology - Question 11 - 2019 - Paper 1
Step 1
Which is the genotype of a person with cystic fibrosis?
Answer
To determine the genotype of a person with cystic fibrosis, we need to understand that cystic fibrosis is caused by a recessive allele (f). This means that an individual must have two copies of the recessive allele (ff) to express the condition.
Considering the options:
- A: Heterozygous and ff - This is contradictory, as heterozygous indicates one dominant allele and one recessive allele (Ff).
- B: Heterozygous and Ff - This would not result in cystic fibrosis, since the presence of the dominant allele (F) masks the recessive allele.
- C: Homozygous and ff - This is the correct choice since a person with two recessive alleles (ff) will have cystic fibrosis.
- D: Homozygous and FF - This would mean the individual does not have cystic fibrosis, as they are homozygous for the dominant allele.
Thus, the correct answer is C: Homozygous and ff.