Two carrier parents for a recessive trait have a child. What is the probability the child will be affected?

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Multiple Choice

Two carrier parents for a recessive trait have a child. What is the probability the child will be affected?

Explanation:
For a recessive trait, being affected requires two copies of the recessive allele (a). If both parents are carriers, their genotypes are Aa. Each parent has a 1/2 chance of passing the recessive allele to the child. To be affected, the child must receive the recessive allele from both parents, so the probability is 1/2 × 1/2 = 1/4, or 25%. The remaining outcomes are unaffected non-carrier (AA) with 25% and carrier (Aa) with 50%.

For a recessive trait, being affected requires two copies of the recessive allele (a). If both parents are carriers, their genotypes are Aa. Each parent has a 1/2 chance of passing the recessive allele to the child. To be affected, the child must receive the recessive allele from both parents, so the probability is 1/2 × 1/2 = 1/4, or 25%. The remaining outcomes are unaffected non-carrier (AA) with 25% and carrier (Aa) with 50%.

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