Download genetics practice test

GENETICS POST TEST
(Practice Test)
1. When crossing two heterozygous individuals, what is the chance of getting a
homozygous individual?
a. 0
b. 25%
c. 50%
d. 75%
e. 100%
2. Given parents AABBCc X AabbCc, assume simple dominance and independent
assortment. What proportion of the progeny will be expected to phenotypically
resemble the first parent?
a. ¼
b. 1/8
c. ¾
d. 3/8
e. All
3. Barring in chickens is due to a sex-linked dominant gene (B). The sex of the
chicks at hatching is difficult to determine, but barred chicks can easily be
distinguished from non-barred chicks. To use this trait so that at hatching all
chicks of one sex are differently colored from those of the opposite sex, what
cross would you make?
a. Barred males X barred females
b. Barred males X non-barred females
c. Non-barred males X barred females
d. Non-barred males X non-barred females
e. None of the above would work
4. A 1:0 phenotypic ratio in a testcross indicates that
a. The alleles are dominant
b. One parent must have been a pure breed
c. The dominant phenotype parent was heterozygous
d. The alleles segregated independently
e. The alleles are co-dominant
5. A couple is consulting with a genetic counselor. Both parents exhibit the normal
phenotype for skin pigmentation, but both had one parent who was an albino.
Albinism is an autosomal recessive trait. What is the probability that their first
child will be albino?
a. 1/8
b.
c.
d.
e.
¼
½
¾
No chance of the disorder
6. In snapdragons, heterozygotes have pink flowers, whereas, the homozygotes have
red or white flowers. When plants with white flowers are crossed with plants
with red flowers, what proportion of the offspring will have pink flowers?
a. 0
b. 25%
c. 50%
d. 75%
e. 100%
7. A recessive allele on the X chromosome is responsible for red-green color
blindness in humans. A woman with normal vision whose father is colorblind
marries a colorblind man. What is the probability that this couple’s son will be
colorblind?
a. 0
b. ¼
c. ½
d. ¾
e. 100%
8. – 10 Refer to the pedigree below. The pedigree indicates color blindness
phenotype. Colorblindness is a recessive sex-linked disorder.
Genotype choices:
A. XX
B. XXc
C. XcXc
D. XY
E. XcY
9. Identify the genotype for individual #10 = ______
10. Identify the genotype for individual #2 = ______
11. Identify the genotype for individual #5 = ______
QUIZ
1. In mice, coat color is controlled by two genes. The wild type color agouti, is
dominant to black coat color, and both are controlled by gene A. A recessive
mutation of gene B causes albinism, regardless of the genotype at locus A. The
offspring of the two mice have the following ratio:
9/16 agouti, 3/16 black and 4/16 albino
What are the genotypes and phenotypes of the parents?
What type of gene interaction is occurring?
2. Sue is Gus’ wife. She has blood type A while both of Gus’ parents were
homozygous A. Becky has type O blood and her husband Cooper is type B.
Cooper’s parents were both type AB. All four were stranded on a desert island
for 14 months. Except for Clifford, a nearby Filipino student-teacher/male model
with blood type B, there were no visitors to the island. By the end of their stay,
both women gave birth to babies. In the confusion of leaving the island, the
babies got mixed up. Baby boy #1 was type AB and baby boy #2 was type O.
a. Who were the parents of baby boy #1?
b. Who were the parents of baby boy #2?