Multiple Choice
In a family where both parents are heterozygous carriers for cystic fibrosis (genotype Ff), what is the probability that their daughter Irene is a carrier (heterozygous) for the disease? Express your answer as a percentage.
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2. Mendel's Laws of Inheritance
Probability and Genetics
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Charles has normal blood clotting, while Marie is a carrier for hemophilia (an X-linked recessive disorder). What is the probability that their female child will suffer from hemophilia?
A
50%
B
100%
C
25%
D
0%
Verified step by step guidance1
Identify the inheritance pattern: Hemophilia is an X-linked recessive disorder, meaning the gene causing hemophilia is located on the X chromosome, and the disorder manifests when a male has the affected X chromosome or a female has two affected X chromosomes.
Determine the genotypes of the parents: Charles has normal blood clotting, so his genotype is XY with a normal X chromosome. Marie is a carrier, so her genotype is X^H X^h, where X^H is the normal allele and X^h is the hemophilia allele.
Consider the possible X chromosomes passed to the female child: The female child will inherit one X chromosome from Charles (which is normal, X^H) and one X chromosome from Marie (which can be either X^H or X^h with equal probability).
Calculate the probability that the female child inherits two affected alleles (X^h X^h): Since Charles can only pass a normal X^H, the female child cannot inherit two X^h alleles and therefore cannot have hemophilia.
Conclude that the female child can either be a carrier (X^H X^h) or have normal blood clotting (X^H X^H), but the probability of suffering from hemophilia is 0%.
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