Genetics Practice Test
Name________________________
1. Long wings (L) on fruit flies are dominant to short wings on fruit flies. A
homozygous long winged male is crossed with a heterozygous female. What is the
probability that their offspring would be short winged?
2. Hemophilia (h), a sex-linked disorder, is a genetic disease. A mother is a
carrier for hemophilia. The father has hemophilia. What are the odds that, if
they have a daughter, she will be a hemophiliac?
3. Icthyosis (a skin disorder)(i), a sex-linked disorder, is a genetic disease.
A female carrier and a male with normal skin want to have children.
What are the odds that, if they have a daughter, she will have Icthyosis?
4. In squash, white fruit (W) is dominant over yellow fruit. Suppose two white
squash were crossed, and they had 120 offspring plants. 90 of the plants had
white fruit and 30 of the plants had yellow fruit. What would be the likely
genotypes of the parents?
5. A woman with BO blood marries a man with AO blood. What is the
probability that they would have a child with type AB blood?
AA, AO= Type A
BB, BO= Type B AB=Type AB OO= Type O
6. In 4 O’clock flowers the presence of a heterozygote reveals an intermediate
between the 2 parents. Suppose a homozygous red (R) plant was crossed with a
heterozygous pink plant. What is the probability that they would have a red
offspring?
RR-Red
Rr-Pink
rr-white
7. In 4 O’clock flowers the presence of a heterozygote reveals an intermediate
between the 2 parents. Suppose a heterozygous pink plant was crossed with a
homozygous (r) white plant. What is the probability that they would have a
pink offspring?
RR-Red
Rr-Pink
rr-white
8. In 4 O’clock flowers the presence of a heterozygote reveals an intermediate
between the 2 parents. Suppose a heterozygous pink plant was crossed with
another heterozygous pink plant. What would be the probability of having a
pink offspring?
RR-Red
Rr-Pink
rr-white
9. What is the difference between a homozygote and heterozygote?
10. What is the relationship between DNA, genes, and chromosomes?
Answer Key
1. 0%
2. 50%
3. 0%
4. Ww and Ww
5. 25%
6. 50%
7. 50%
8. 50%
9. Homozygotes have two of the same alleles (BB
or bb). Heterozygotes have two different alleles
10. DNA is the genetic material found on
chromosomes. Sequences of DNA that code for
certain traits (like eye color) are called genes.