1. What are the sexes and eye colors of flies with the following genotypes?
X R X r female, red _ X R Y _ male, red _ X r X r _ female, white _
X R X R _ female, red _ X r Y _ male, white __
2. What are the genotypes of these flies:
white eyed, male ___ X r Y _____ red eyed female (heterozygous) _ X R X r __
white eyed, female ___ X r X r ___ red eyed, male __ X R Y ____
3. Show the cross of a white eyed female X r X r with a red-eyed male X R Y .
Results in all red eyed females, and all white eyed males
4. Show a cross between a pure red eyed female and a white eyed male.
What are the genotypes of the parents:
__ X R X R ____ and _____ X r Y ____
white eyed, male ____
white eyed, female __
red eyed, male _ 1/2 __
red eyed, female _ 1/2 ___
5. Show the cross of a red eyed female (heterozygous) and a red eyed male.
What are the genotypes of the parents?
___ X R X r ___ & ______ X R Y _____
white eyed, male _ 1/4 _
white eyed, female __
red eyed, male __ 1/4 __
red eyed, female _ 1/2 _
Math: What if in the above cross, 100 males were produced and 200 females. How many total red-eyed flies would there be?
_ 50 + 200 = 250 total __
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)
Show the cross of a man who has hemophilia with a woman who is a carrier.
What is the probability that their children will have the disease? _ 1/4 (female) + 1/4 (males) or 2/4 total __
7. A woman who is a carrier marries a normal man. Show the cross. What is the probability that their children will have hemophilia? What sex will a child in the family with hemophilia be? 1/4, only boys
8. A woman who has hemophilia marries a normal man. How many of their children will have hemophilia, and what is their sex?
all boys will have hemophilia, or half of their children
9. In cats, the gene for calico (multicolored) cats is codominant. Females that receive a B and an R gene have black and oRange splotches on white coats. Males can only be black or orange, but never calico.
Here’s what a calico female’s genotype would look like: X B X R
Show the cross of a female calico cat with a black male?
What percentage of the kittens will be black and male? __ 1/4 ____
What percentage of the kittens will be calico and male? _ 0 _____
What percentage of the kittens will be calico and female? _ 1/4 _____
10. Show the cross of a female black cat, with a male orange cat.
What percentage of the kittens will be calico and female? _ 2/4 (all females) ___What color will all the male cats be? _ black _