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Genetics answer explanations

Review worked answers and explanations for Genetics. Aligned to Pearson Edexcel GCSE (9-1) Biology.

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Question 160 of 175

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Cystic fibrosis is a genetic disorder caused by a recessive allele (f). Individuals with at least one dominant allele (F) do not have the condition. A couple, both of whom are carriers for cystic fibrosis, decide to have children. a) Draw a Punnett square to show the possible genotypes and phenotypes of their offspring. b) Calculate the probability, as a percentage, that their first child will: i) have cystic fibrosis. ii) be a carrier for cystic fibrosis. c) Explain how pedigree analysis could be used to determine if a family trait is dominant or recessive, even without genetic testing. [9 marks]

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