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Genetics BIOL2221
EXAM #1
Chs 2-4
NAME___________________________________
DATE________________
Multiple Choice (3.35 each) Total = 100pts. Choice the choice that best answers the question! Good
luck!
1. Could the characteristic followed in the pedigree be caused by an autosomal dominant disease?
Why or why not?
I
2
1
3
4
II
1
2
3
4
5
III
1
a. b. c. d. e. Yes, all individuals fit the autosomal dominant inheritance pattern.
No, the offspring of I-1 and I-2 contradict an autosomal dominant inheritance.
No, the offspring of I-3 and I-4 contradict an autosomal dominant inheritance.
No, the offspring of II-3 and II-4 contradict an autosomal dominant inheritance.
Yes, the offspring of I-1 and I-2 are consistent with an autosomal dominant inheritance pattern.
2. Round seeds (R) is dominant to wrinkled seeds (r), and yellow seeds (Y) is dominant to green
seeds (y). A plant of unknown genotype is testcrossed to a true-breeding plant with wrinkled and
green seeds. The offspring produced were 53 round and yellow, 49 round and green, 44 wrinkled
and yellow, 51 wrinkled and green. What is the likely genotype of the parent in question?
a. b. c. d. e. RRYY
RrYY
RRYy
RrYy
rryy
3. Hair color is determined in Labrador retrievers by alleles at the B and E loci. A dominant allele B
encodes black pigment, whereas a recessive allele b encodes brown pigment. Alleles at a second
locus affect the deposition of the pigment in the shaft of the hair; dominant allele E allows dark
pigment (black or brown) to be deposited, whereas recessive allele e prevents the deposition of
dark pigment, causing the hair to be yellow. A black female Labrador retriever was mated with a
yellow male. Half of the puppies were black and half were yellow. If the genotype of the black
female parent was Bb Ee, then what was the genotype of the other parent?
a. b. c. d. e. bb ee
bb EE
Bb ee
BB ee
BB EE
Genetics BIOL2221
EXAM #1
Chs 2-4
4. Which of the following statements about meiosis is false?
a. b. c. d. e. Homologous chromosomes separate from each other during anaphase I.
Sister chromatids separate from each other during anaphase II.
Crossing over takes place during prophase I.
DNA replication occurs between the first and second divisions.
The chromosome number is reduced by one-half at the end of the first division.
5. A dog has a diploid chromosome number of 78. How many separate DNA molecules should be
present at metaphase of mitosis?
a. b. c. d. e. 39
78
156
4
None of the above answers is correct.
6. In Labrador retrievers, black coat color is dominant to brown. Suppose that a black Lab is mated
with a brown one, and the offspring are 4 black puppies and 1 brown. What can you conclude
about the genotype of the black parent? (Assume that B is the allele for black and b is the allele for
brown.)
a. b. c. d. e. The genotype must be BB.
The genotype must be bb.
The genotype must be Bb.
The genotype could be either BB or Bb.
The genotype cannot be determined from these data.
7. Freckles are caused by a dominant allele. A man has freckles but one of his parents does not have
freckles. The man has fathered a child with a woman that does not have freckles. What is the
probability that their child has freckles?
a. b. c. d. e. 1/4
1/3
1/2
2/3
3/4
Genetics BIOL2221
EXAM #1
Chs 2-4
8. Suppose that the “fabulous” phenotype is controlled by two genes, A and B, as shown in the
diagram below. Allele A produces enough enzyme 1 to convert “plain” to “smashing.” Allele a
produces no enzyme 1. Allele B produces enough enzyme 2 to convert “smashing” to “fabulous.”
Allele b produces no enzyme 2. The A and B genes are both autosomal and assort independently.
Enzyme 1
Plain
Enzyme 2
Smashing
Fabulous
What will be the phenotype(s) of the F1 offspring of a true-breeding “fabulous” father and a truebreeding “plain” mother (aa bb)?
a. b. c. d. e. All “plain”
All “smashing”
All “fabulous”
“Plain” females and “fabulous” males
“Fabulous” females and “smashing” males
9. Which of the following statements is true?
a. The genotype is the physical appearance of a trait.
b. Alleles, genes, and loci are different names for the same thing.
c. The phenotype of a dominant allele is never seen in the F1 progeny of a monohybrid
cross.
d. A testcross can be used to determine whether an individual is homozygous or
heterozygous for a dominant allele.
e. All of these statements are true.
10. Joan is phenotypically normal but had a child with the autosomal recessive disease cystic fibrosis
(CF) from a previous marriage. Joan’s father has hemophila A, a sex-linked recessive condition
where the blood fails to clot properly. Her father has survived due to recent treatment advances.
Joan now intends to marry Bill, who is also phenotypically normal but who has a sister, Jill, with
CF. Bill’s parents are phenotypically normal, and there is no history of hemophilia A in his family.
Assume that Joan and Bill do marry and have a child. What is the probability that this child will
have CF, but will not have hemophilia A ? (Hint: This problem requires that you utilize concepts
from Chapter 3 as well as Chapter 4.)
a. b. c. d. e. 1/8
1/12
1/24
3/32
5/32
11. Interactions among the human ABO blood group alleles involve _______ and ________.
a. b. c. d. e. codominance; complete dominance
codominance; incomplete dominance
complete dominance; incomplete dominance
epistasis; complementation
continuous variation; environmental variation
Genetics BIOL2221
EXAM #1
Chs 2-4
12. In the endangered African watchamakallit, the offspring of a true-breeding black parent and a truebreeding white parent are all gray. When the gray offspring are crossed among themselves, their
offspring occur in a ratio of 1 black:2 gray:1 white. Upon close examination of the coats, each hair
of a gray animal is gray. What is the mode of inheritance?
a. b. c. d. e. One gene pair with black dominant to white
One gene pair with codominance
One gene pair with incomplete dominance
Two gene pairs with recessive epistasis
Two gene pairs with duplicate genes
13. What is the expected outcome for a human embryo with the XXXY chromosome constitution?
a. b. c. d. e. It would likely develop into a female who will not respond to the hormone testosterone.
It would likely develop into a sterile male with reduced testes.
It will always abort early in development before birth.
It would likely develop into a tall female who may be slightly cognitively impaired.
It would likely develop into a fertile man with a completely normal male phenotype.
14. In a cell with four chromosomes in its gametes, how many different combinations of chromosomes
in the gametes can occur?
a. 2
b. 4
c. 8
d. 16
e. 32
15. From the following cross involving four genes, Aa;BB;Cc;Dd x Aa;Bb;Cc;DD, what is the
probability of obtaining homozygous dominant genotypes for each gene?
a. 1/4
b. 1/16
c. 1/32
d. 1/64
e. 1/256
16. From the following cross involving four genes, Aa;BB;Cc;Dd x Aa;Bb;Cc;DD, what is the
probability of obtaining AaBBCcDd, AaBbCcDd, or aaBbccDD?
a. 1/3
b. 1/16
c. 9/64
d. 27/256
e. 81/256
Genetics BIOL2221
EXAM #1
Chs 2-4
17. A novel genetic mutation which results in deafness, is identified in wild dogs and is determined to
be 25% penetrant with unvarying expressivity. This means that:
a. All dogs which carry the mutation will be completely deaf
b. All dogs which carry the mutation will have a 25% reduction in hearing ability
c. 25% of dogs which carry the mutation will be completely deaf
d. 75% of dogs which carry the mutation will be slightly hard of hearing
e. 75% of dogs which carry the mutation will be completely deaf
18. Coat color is determined by two loci in large cats. Two pink panthers fall in love and produce a
large litter of baby panthers with the following phenotypic ratios: 12/16 pink; 3/16 black; and 1/16
white. What might be the genotype of the pink progeny?
a. b. c. d. e. A_ B_
A_ bb
aa B_
aa bb
A_ B_ and A_ bb
19. Two genes (W and X), with two alleles each, are known to contribute toward the color of wolves.
A dihybrid heterozygous cross between two wolves produces pups of three different colors –
black, brown and grey in a ratio of 9:3:4. What is the genotype of the grey wolves?
a. W_ xx
b. ww X_
c. W_ X_
d. a or b are correct
e. a, b or c are correct
20. A botanist is growing a newly discovered flower, called a Dragon flower, which comes in only
two color varieties – green and blue. The botanist has determined (1) that there are two genes
which interact to produce the color varieties and (2) at least one dominant allele must be present at
both loci for the green color to be seen. From these data, a dihybrid heterozygous cross will
produce green and blue flowers in the ratio:
a. 1:1
b. 12:4
c. 13:3
d. 9:7
e. 3:1
21. In wolves, the allele for black fur (B) is dominant to the allele for grey fur (b). In a cross between
two heterozygous wolves we would expect the F1 ratio of black to grey pups to be:
a. 1:1
b. 1:2
c. 2:1
d. 3:1
e. 1:4
Genetics BIOL2221
EXAM #1
Chs 2-4
22. In actuality, the F1 ratio between black and grey wolves from a heterozygous cross is observed to
be 2:1. This could be explained by:
a. Lethality of the homozygous dominant genotype
b. Lethality of the heterozygous genotype
c. A loss of the recessive allele
d. Either a or b
e. Either a or c
23. One gene is involved in specifying flower petal color. A true breeding red flower producing plant
and a true breeding white flower producing plant are crossed to produce F1 offspring all of which
have pink flowers. When the F1 offspring are selfed, when can we predict about the phenotype of
the F2 generation?
a. They will all be pink
b. The will all be white
c. They will be either red or white
d. All three petal colors will be visible in the offspring
e. The petals colors of the F2 will be a slightly lighter shade of pink than the F1
24. In the accompanying figure, the chance that individual IV-7 is a heterozygous carrier is ________.
a. b. c. d. e. 1/4
1/3
1/2
2/3
3/4
25. A pure-breeding female fruit fly with a yellow body is crossed to a pure-breeding male fruit fly
with a gray body. All female offspring from the cross have gray bodies and all males have yellow
bodies. Body color is likely a(n)________trait, and the gray allele is ________.
a. Autosomal; dominant
b. Autosomal; recessive
c. X-linked; dominant
d. X-linked; recessive
Genetics BIOL2221
EXAM #1
Chs 2-4
26. The amount of DNA in the cell of a newly discovered animal is measured at different points during
meiosis and the mitotic cycle. It is found to have 2.4pg, 4.8pg and 9.6pg. At what phase of the meiosis
is the amount of DNA likely to be 4.8pg?
a. Prophase I
b. Metaphase I
c. Anaphase I
d. Prophase II
e. Telophase II
27. What dosage compensation mechanism is employed by female placental mammals?
a. polar bodies
b. Y-inactivation
c. X-inactivation
d. X nondisjunction
e. X chromosome crossing over
28. A dihybrid has the genotype AaBb. After a normal mitotic division into two daughters cells,
one daughter cell will have the genotype ________ and the other will have the genotype
________.
a. Aa; Bb
b. AaBb; AaBb
c. AB; ab
d. Ab; aB
e. AABB; aabb
29. A dihybrid has the genotype AaBb. The diagram depicts the chromosome composition of
different cells from the animal. Which of the following represents the contents of a cell in G2
phase (before cell division begins)?
A) Cell G
B) Cell H
C) Cell K
D) Cell M
E) Cell P
Genetics BIOL2221
EXAM #1
Chs 2-4
30) The P value is a quantitative expression of the probability that the results of another experiment of the
same size and structure will deviate from expected results as much as or more than by chance.
The greater the difference between observed and expected results of an experiment, ________.
a. the lower the χ2 value and the lower the P value
b. the greater the χ2 value and the greater the P value
c. the greater the χ2 value and the lower the P value
d. the lower the χ2 value and the greater the P value
e. the greater the χ2 value; but the P value is unaffected