Sex-linked Inheritance

Hemophilia is an X-linked recessive disorder (Xh) that is passed through generations and can be traced by using a pedigree. What is the probability that a female child of Charles and Marie would suffer from hemophilia?

0 percent

Duchenne muscular dystrophy is an X-linked recessive disorder. What is the probability that a female offspring of the cross that is shown above would have a recessive allele for Duchenne muscular dystrophy disorder?

100 percent

Hemophilia is an X-linked recessive disorder. What is the probability of the offspring having hemophilia for the cross that is shown in the Punnett square?

50 percent

Drosophila eye color is an X-linked trait. Red eye color is dominant, and white eye color is recessive. Which Punnett square shows a cross in which the probability of offspring will have red eyes is 100 percent?

A (the one with XR XR on the side and Xr Y on top)

Which is not considered a sex-linked trait?

A patient who is Rh- can receive only Rh- blood.

Which pedigree symbol is used to represent a female carrier of a recessive X-linked trait?

B (half filled circle)

Which symbol is used to label a male that expresses a sex-linked disorder on a pedigree?

D (purple square)

Which statement about inheritance is true?

Fathers always determine the gender of the offspring in humans.

What was Thomas Hunt Morgan's main contribution to science?

He discovered that certain traits were linked to the X chromosome.

Which statement is always true when describing sex-linked inheritance?

The alleles are found on the X or Y chromosome.

How are the alleles for sex-linked traits inherited?

They are passed from parents to offspring on the X and Y chromosomes.

Which allele combination represents a female who is a carrier for an X-linked recessive disorder?

XRXr

Which allele combination represents a female who is heterozygous for a sex-linked trait?

XRXr

What is genotype for a recessive trait found on the female chromosome?

Xh

Which combination of alleles are always involved in the inheritance of a sex-linked trait?

alleles that are carried on X and Y chromosomes

Hemophilia is an X-linked recessive disorder (Xh) that is passed through generations and can be traced by using a pedigree. Based on the pedigree that is shown, which describes John?

does not have hemophilia

What is the purpose of using a pedigree?

to understand patterns of inheritance in organisms