Genetics Practice Packet
Name: _______________________
1) Hemophilia is a recessive X-linked trait. What will be the results of mating a healthy, noncarrier female and a hemophiliac male?
Label all phenotypes!
2) A man and his wife are both heterozygous for brown eyes. They have three children with
brown eyes. What would you predict their fourth child will have?
3) Summer squashes can be yellow or white, depending on if they are being used for food or
decoration. A farmer is experimenting with his fields to see what will happen if he crosses a
yellow squash (YY) with a white squash (yy). He researched and found out that the colors of
summer squash are codominant, but he’s not sure what that means. Create a punnett square for
this cross & describe all possible phenotypes.
4) In human blood types, A and B are codominant and O is recessive. A man with type AB
marries a woman with Type O. What are the possible genotypes and phenotypes of their
offspring?
5) Could a mother with blood type B and a father with blood type O produce offspring with blood
type AB? Prove your answer with a punnett square!
6) Color blindness is a recessive sex-linked trait on the X chromosome. An organism has normal
eyesight (N) unless they have the recessive colorblind (n) phenotype. A heterozygous woman
marries a normal man. What will their offspring be like?
7) In fruit flies, long wings (L) is dominant to short wings (l). Two long winged flies produce 49
short winged flies and 148 long winged flies. What were the genotypes of the parents?
8) In one type of watermelon, the skin can be bright Kelly green (G) or pale yellow (g). This trait
is incompletely dominant so there is a third phenotype possible. If a gardener placed male pollen
from a homozygous green watermelon plant on the female eggs of a homozygous yellow
watermelon plant, what will the offspring look like? Show the genotypes in a punnett square and
describe the phenotype!
9) Next, cross two of the offspring plants from problem #8 and describe all possible phenotypes.
10) In fruit flies, eye color is a sex-linked trait. Red eyes (R) are dominant and white eyes (r) are
recessive. Cross a homozygous red eyed female with a white eyed male and label all
phenotypes.
11) Radishes may be long, oval, or round: long is dominant, round recessive, and oval is a
mixture of the two. What is this called? If a farmer has all oval plants in his garden, what will be
the phenotypes of the F1 generation?
12) People with sickle-cell anemia have a problem with the blockage of capillaries due to a
mutation in the hemoglobin gene. This usually causes death before reproductive age so someone
with two recessive alleles (nn) rarely produces offspring. The heterozygous condition of this trait
produces people of generally good health, but some sickle shaped cells. These people are called
“carriers”. Two heterozygous individuals are planning a family and have asked you to tell them
their chances of having a sickle cell child. What would you tell them?
13) In short horned cattle, genes for red and white coats occur. Crosses between a red (RR) and
a white (rr) produce an offspring whose coat appears a reddish-grey or roan color. A roan cow
mates with a white bull. What will be the phenotypes of the offspring?
14) In cats, black color is due to the allele B and yellow color is due to b. Yellow is incompletely
dominant to black with the heterozygous condition results in a color known as calico (black,
white, and yellow spotted). These genes are sex-linked. What kinds of offspring would be
expected from a cross between a black male and a calico female? What interesting fact do you
now understand about calico cats?
15) In wild turkeys, a dominant allele (B) produces familiar bronze colored turkeys and a
recessive allele (b) produces a white color. Another dominant allele produces normal feathers (N)
and its recessive allele (n) produces strange hair-like feathers.
A male turkey heterozygous for color with strange hair-like feathers mates with a female that is
heterozygous for both traits. Create a dihybrid punnett square & answer the following questions!
How many turkeys are bronze with normal feathers?
How many turkeys are bronze with strange, hair-like feathers?
How many turkeys are white with normal feathers?
How many turkeys are white with strange, hair-like feathers?
16) Tall tomato plants (T) is dominant over short tomato plants (t). What type of plant will result if
a plant homozygous to be tall crosses with a heterozygous plant?
17) Short fur in rabbits is dominant to long fur. What phenotype ratio would you expect from a
heterozygous female crossing with a male with long fur?
18) Use the following information to answer the question:
B: Brown eyes
b: Blue eyes
R: Right handed
r: Left handed
A female that is heterozygous for eye color and homozygous dominant for handedness and a
male that is heterozygous for eye color and homozygous recessive for handedness produce
offspring. Make a punnett square and do the genotypes and phenotypes of the possible offspring.
*List all possible genotypes and their frequency (___/16):
*List all possible phenotypes and their frequency: