Use the following list for questions 1-4
a. multiple alleles
b. incomplete dominance
c. polygenes
d. epistatic gene
e. pleiotropic gene
1. Individuals with Marfan syndrome tend to be
tall, nearsighted, and have a weak aorta. e.
2. Produces a bell curve of phenotypes. c.
3. When a recessive pair of alleles at one locus
prevents the expression of a dominant allele at
another locus. d.
a.
4. The ABO blood group system is an example.
A boy is color blind (sex-linked recessive)
and has a continuous hairline (autosomal
recessive). Which could be the genotype
of his mother?
a. bbww
b. XbYWw
c. bbXwXw
d. XBXbWw
e. XBXBww
Answer: d
What is a genetic cross called between an
individual of unknown genotype and a
homozygous recessive individual?
a. a self-cross
b. a testcross
c. a hybrid cross
d. an F cross
e. a dihybrid cross
Answer: b
A couple has three children, all of whom
have brown eyes and blond hair. Both
parents are homozygous for brown eyes
(BB), but one is blond (rr) and the other
is a redhead (Rr). What is the probability
that their next child will be a brown-eyed
redhead?
a. 1/16
d. 1/2
b. 1/8
e. 1
Answer: d.
c. 1/4
Given the 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. 1/4
b. 1/8
c. 3/4
d. 3/8
e. 1
Answer: c
Feather color in budgies is determined by
two different genes that affect the pigmentation of the outer feather and its core. Y_B_
is green, yyB_ is blue, Y_bb is yellow, and
yybb is white. A green budgie is crossed
with a blue budgie. Which of the following
results is NOT possible?
a. all green offspring
b. all blue offspring
Answer: e
c. all white offspring
d. all yellow offspring
e.All of the above are possible
The inheritance of color in budgies is an
example of what genetic phenomenon?
a. pleiotropy
b. penetrance
c. polygenic inheritance
d. dominance
e. epistasis
Answer: e
In cattle, roan coat color (mixed red and white)
occurs in the heterozygous (Rr) offspring of
red (RR) and white (rr). When two roan cattle are
crossed, the phenotypes of the progeny are
found to be in the ratio 1 red: 2 roan: 1 white.
Which of the following crosses would produce the
highest percentage of roan cattle?
a. red x white
Answer: a
b. roan x roan
c. white x roan
d. red x roan
e. all of the above would give the same percentage
of roan cattle.
A man who has an x-linked allele will pass
it on to
a. all of his daughters
b. half of his daughters
c. all of his sons
d. half of his sons
e. all of his children
Answer: a
The following is a map of 4 genes on a
chromosome:
A
5
W
3
E
12
G
Between which two genes would you
expect the highest frequency of
recombination?
a. A and W
d. A and E
b. W and E
e. A and G
c. E and G
Answer: e.
The phenotypic ratio from a genetic cross
is 1:1:1:1. The genotypes of the parents
are
a. TTGG x TtGg
b. TtGG x Ttgg
c. TtGg x ttgg
d. Ttgg and ttgg
e. ttgg x ttgg
Answer: c
An organism has the genotype DDGg.
How many unique kinds of gametes can
this organism produce?
a. none
b. one
c. two
d. four
e. eight
Answer: c
Two organisms, each with the genotype
TtGg mate. The chance of producing an
offspring that has the dominant phenotype
for height and the recessive phenotype
for color is
a. 9/16
b. 7/16
c. 6/16
d. 3/16
e. 1/16
Answer: d
Select the wheat plant genotype with the
darkest-colored seeds (the dominant
allele of each gene pair contributes an
equal amount of red pigment to the seed).
a. AaBbCc
b. AaBBcc
c. AaBbCC
d. AabbCc
e. AAbbCc
Answer: c
A culture of white-eyed fruit flies was maintained
for many generations. Females from the stock
white-eyed culture were crossed with red-eyed
(wild type) males. The F1 females were crossed
with the white eyed males from the original
culture. The resulting phenotypes are listed.
P1 cross: white eyed female x red eyed male
F1 generation : 100% females red eyed
100% males white eyed
F1 cross: red eyed females x white eyed males
F2 generation: 50% females red eyed,
50% females white eyed
50 % males red eyed,
50 % males white eyed
The best explanation for the red eyed
F1 females is
a. mutation
b. culture contamination
c. dominance
d. multiple loci
e. sex-influenced traits
Answer: c
There are white eyed females in the
F2 generation because
a. white is a dominant allele.
b. the white allele is autosomal.
c. a mutation has occurred.
d. these F2 females have two white alleles.
e. the white allele is located on the Y
chromosome.
Answer: d
Which of the following best describes the
mode of inheritance of eye color in the
white culture.
a. autosomal
b. dominant
c. located on the Y chromosome
d. sex-linked
e. lethal
Answer: d
Which represents the genotype of a carrier
Female?
a. XAXA
b. XAXa
c. XaXa
d. XAY
e. XaY
Answer: b
The shaded individuals are affected with
a disorder; the unshaded individuals are
not affected. The disorder is most probably
a. x-linked dominant
b. autosomal recessive
c. autosomal dominant
d. epistatic
e. x-linked recessive
Answer: c
Which of the following are possible
genotypes for persons 7 and 8?
a. Aa x Aa
b. AA x Aa
c. Aa x aa
d. aa x aa
e. AA x AA
Answer: c
A type O woman has a type O child. The
father could have the blood type
a. A only.
b. B only.
c. A or B
d. A, B, or AB
e. O only.
Answer: c
Which genotype could not be produced
if both parents have type A blood?
a. type A
b. type O
Answer: e
c. type AB
d. type B
e. both c and d are correct
f. all of the above are correct
If the husband is a carrier of Tay Sachs
disease (recessive), but the wife is
homozygous normal, what are the
chances of having a baby with Tay Sachs?
a. 0%
b. 25%
c. 50%
d. 75%
e. 100%
Answer: a
Select the syndrome that is trisomy.
a. Turner syndrome
b. Klinefelter syndrome
c. PKU
d. Down syndrome
e. b and d
f. a, b, and d
Answer: f
a. 3:1
b. 9:3:3:1
c. 1:1
d. 1:1:1:1
Match the cross with its ratio.
1.TtYy xTtYy b.
a.
2. Tt xTt
c.
3. Tt x tt
4. TtYy x ttyy d.
A person has a genetic disorder. Which
is inconsistent with autosomal recessive
inheritance?
a. Both parents have the disorder.
b. Both parents do not have the disorder.
c. All the children (males and females)
have the disorder.
d. All of these are inconsistent
e. All of these are consistent.
Answer: e
a. Cystic fibrosis
b. Huntington’s disease
c. Hemophilia
d. Tay-Sachs disease
1. autosomal dominant b.
d.
2. most often seen among Jewish people
3. X-linked recessive c.
4. thick mucus in lungs and pancreatic
ducts a.
A male has a genetic disorder. Which of
the following is inconsistent with X-linked
recessive inheritance?
a. Both parents do not have the disorder.
b. Only males in a pedigree chart have
the disorder.
c. Only females in previous generations
have the disorder.
d. Both a and c are inconsistent.
Answer: c.
B represents a dominant allele and b
represents a recessive allele. If in
1,000 offspring 75% express the
dominant trait, which of the following
are most probably the genotypes of the
two parents?
a.
b.
c.
d.
Bb and Bb
Bb and bb
BB and bb
BB and Bb
Answer: a
In dogs, the trait for a dark coat (D) is dominant
to an albino coat (d) and the trait for short hair
(S) is dominant to long hair (s). In a particular
cross of dogs, the probability of the offspring
having a dark coat is 1/2 and the probability of
having short hair is ¾. Which of the following
most probably represents the parental
genotypes?
a. DdSs and ddSs
b. DdSs and DdSs
c. DdSs and ddss
Answer:
a
d. DDSs and ddSs
In dogs, eye color is controlled by a single
gene with two alleles. When a homozygous
brown eyed dog is crossed with a homozygous
blue eyed dog, green eyed offspring are
produced. If the green eyed dogs are mated
with each other, what percent of their offspring
will have green eyes?
a.
b.
c.
d.
0%
25%
50%
75%
A child has blood type B. The
mother has blood type A. The
father must have which blood
type(s)?
a.
b.
c.
d.
AB only
Either AB or B
Either AB or O
Either AB or A
In humans, color blindness is an xlinked
recessive characteristic. If a color blind
woman has offspring with a normal
sighted male, what percentage of their
boys will be color blind?
a.
b.
c.
d.
25%
50%
75%
100%