Name _____________________________
Genetics: X L i nked G e n e s
****In fruit flies, eye color is a sex linked trait. Red is dominant to white ****
1. What are the sexes and eye colors of flies with the following genotypes:
X R X r _____________ X R Y ____________ X r X r ____________
X R X R ____________ X r Y ____________
2. What are the genotypes of these flies:
white eyed, male ____________ red eyed female (heterozygous) ________
white eyed, female ___________ red eyed, male ___________
3. Show the cross of a white eyed female X r X r with a red-eyed male X R Y .
4. Show a cross between a pure red eyed female and a white eyed male.
What are the genotypes of the parents:
___________& _______________
How many are:
white eyed, male ____
white eyed, female ____
red eyed, male ____
red eyed, female ____
5. Show the cross of a red eyed female (heterozygous) and a red eyed male. What are the genotypes
of the parents?
___________ & ________________
How many are:
white eyed, male____
white eyed, female ___
red eyed, male ____
red eyed, female ____
6. In humans, hemophilia is a sex linked trait. Females can be normal, carriers, or have the disease.
Males will either have the disease or not (but they won’t ever be carriers)
Math: What if in the above cross, 100
males were produced and 200 females.
How many total red-eyed flies would there
be?
____________
