If a recessive disease appears only when both factors are recessive, why does risk increase when both parents are carriers?
Answer and explanation
Correct answer: Both parents can pass the recessive factor
The governing concept is recessive inheritance. A carrier usually has one normal dominant allele and one recessive disease allele, so the disease is not expressed. If both parents are carriers, each can pass the recessive allele to a child; the child may receive two recessive alleles and express the disease. In a simple autosomal case, the probability is 1 in 4 for each pregnancy, so option A is correct.
Frequently asked questions
What is the correct answer to this question?
Both parents can pass the recessive factor
Why is this the correct answer?
The governing concept is recessive inheritance. A carrier usually has one normal dominant allele and one recessive disease allele, so the disease is not expressed. If both parents are carriers, each can pass the recessive allele to a child; the child may receive two recessive alleles and express the disease. In a simple autosomal case, the probability is 1 in 4 for each pregnancy, so option A is correct.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: World of Living. Topic: Heredity and Evolution.
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