PATHOLOGY MCQ
GENETICS AND DISEASE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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His father has the recessive blue eye characteristic.
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His mother has the recessive blue eye characteristic.
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Both of his parents have recessive blue eye characteristics.
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Neither of his parents have the recessive blue eye characteristic.
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Detailed explanation-1: -Alex has blue eyes, and both of his parents have brown eyes. What can most likely be concluded about Alex’s parents? His father has the recessive blue eye characteristic.
Detailed explanation-2: -Recessive alleles only show their effect if the individual has two copies of the allele (also known as being homozygous?). For example, the allele for blue eyes is recessive, therefore to have blue eyes you need to have two copies of the ‘blue eye’ allele.
Detailed explanation-3: -Answer and Explanation: A woman who is heterozygous for brown eyes will have the genotype “Bb” while a man who has blue eyes will be homozygous recessive with the genotype “bb". The genotype ratio is 2:2 which can be reduced to 1:1. It is 2:2 because there are two “Bb” and two “bb".