Problem 1: Crossing a white-eyed female and red-eyed male fly

In a cross between a white-eyed female fruit fly and red-eyed male, what percent of the female offspring will have white eyes? (White eyes are X-linked, recessive)

A. 100%

B. 25%

C. 50%

D. 75%

E. 0%

Problem 2: Test cross of a red-eyed female fly

A female Drosophila of unknown genotype was crossed with a white-eyed male fly, of genotype X^rY(r = white eye allele is recessive, R= red-eye allele is dominant.) Half of the male and half of the female offspring were red-eyed, and half of the male and half of the female offspring were white-eyed. What was the genotype of the female fly?

A.	XRY
B.	XR XR
C.	XrXr
D.	XrY
E.	XRXr

Problem 3: Predicting the offspring of a homozygous red-eyed female fly

In a cross between a pure bred, red-eyed female fruit fly and a white-eyed male, what percent of the male offspring will have white eyes? (white eyes are X-linked, recessive)

A. 100%

B. 75%

C. 50%

D. 25%

E. 0%

Problem 4: Predicting genotype when phenotype is known

What is the genotype of a red-eyed, yellow-bodied female fruit fly who is homozygous for the eye color allele?
Red eyes (R) and tan bodies (T) are the dominant alleles. (Both traits are X chromosome linked).

A.	XRt XRt
B.	XRt Y
C.	XrT XrT
D.	XrT Y
E.	XRt XRT

Problem 5: Another white-eyed female x red-eyed male fly cross

A white-eyed female fruit fly is crossed with a red-eyed male. Red eyes are dominant, and X-linked. What are the expected phenotypes of the offspring?

A.	All of the females will have red eyes; half of the males will have red eyes, and half of the males will have white eyes.
B.	All of the females and all of the males will have white eyes.
C.	All of the females will have red eyes; all of the males will have white eyes.
D.	All of the females and all of the males will have red eyes.
E.	All of the females will have white eyes; half of the males will have red eyes, and half of the males will have white eyes.

Problem 6: Hemophilia in humans

Hemophilia in humans is due to an X-chromosome mutation. What will be the results of mating between a normal (non-carrier) female and a hemophilac male?

A.	half of daughters are normal and half of sons are hemophilic.
B.	all sons are normal and all daughters are carriers.
C.	half of sons are normal and half are hemophilic; all daughters are carriers.
D.	all daughters are normal and all sons are carriers.
E.	half of daughters are hemophilic and half of daughters are carriers; all sons are normal.

Problem 7: Red-green color blindness in humans

A human female "carrier" who is heterozygous for the recessive, sex-linked trait causing red-green color blindness (or alternatively, hemophilia), marries a normal male. What proportion of their male progeny will have red-green color blindness (or alternatively, will be hemophiliac)?

A. 100%

B. 75%

C. 50%

D. 25%

E. 0%

Problem 8: Offspring of human females who are carriers for X-linked traits

A human female "carrier" who is heterozygous for the recessive, sex-linked trait red color blindness, marries a normal male.

What proportion of their female progeny will show the trait?

A. All

B. 1/2

C. 1/4

D. 0

E. 3/4