Biol. 303
EXAM I 9/23/03
Name___________________________________
-------------------------------------------------------------------------------------------------------------This exam consists of 40 multiple choice questions worth 2.5 points each. On the
separate answer sheet, please fill-in the single best choice for each question. Please
remember to fill-in your student number on the answer sheet. Good luck!
-------------------------------------------------------------------------------------------------------------1.
Eukaryotic cells differ from prokaryotic cells in that
1. prokaryotes do not have DNA.
2. prokaryotes do not have a true nucleus.
3. only eukaryotic cells contain genetic material.
4. eukaryotes are usually smaller than prokaryotes.
2.
A certain mammalian organism has a diploid number of chromosomes equal to 42. This
organism has one pair of sex chromosomes. How many autosomes does a gamete from this
organism have?
1. 42
2. 40
3. 21
4. 20
Use the following information for questions 3-5:
A diploid somatic cell from a rat has a total of 42 chromosomes. As in humans, sex
chromosomes determine sex: XX in females and XY in males.
3.
What is the total number of DNA molecules in a rat cell (nucleus) in G2?
1. 21
2. 42
3. 84
4. 126
4.
What is the total number of telomeres in a rat cell in G2?
1. 42
2. 84
3. 126
4. 168
5.
What is the total number of centromeres in a polar body cell from a rat?
1. 21
2. 40
3. 42
4. 84
6.
When a diploid eukaryotic cell undergoes proliferation, during which part of the cell
cycle does the number of DNA molecules equal "2n" (where the diploid number = 2n)?
1. S
2. G2
3. G1.
4. none of the above.
7.
An allele is
1. a type of cell.
2. a dominant trait.
3. a form of a gene.
4. an imaginary concept.
8.
The figure below shows a chromosomal separation taking place. The letters stand for
genes; capital and lowercase stand for different alleles. 2n in this organism is 4. What process is
shown?
1. anaphase of mitosis
2. telophase of meiosis I
3. anaphase of meiosis I
4. anaphase of meiosis II
A
A
9.
B
C
d
b
C
d
In each one of Mendel's dihybrid crosses,
1. partial dominance was not observed.
2. the phenotypes in the F1 generation segregated in a 3:1 ratio.
3. two distinct phenotypes were observed in the F1 generation.
4. the phenotypes in the F2 generation segregated in a 3:1 ratio.
10.
In a cross between two plants of the following genotypes: (AaBb x AaBb), which of the
following phenotypes should occur at the greatest frequency among the offspring?
1. AB
2. Ab
3. aB
4. ab
11.
Regarding the cross in question 10 above, the genotype Aabb should occur at what
frequency?
1. 1/4
2. 1/8
3. 1/2
4. 1/16
12.
A genetics class has 20 male students and 40 female students. If a student's name is
picked at random from the class roll, what is the probability that the name will belong to a male
student?
1. 20%
2. 33.3%
3. 40%
4. 50%
13.
Each of the following statements about meiosis is true EXCEPT
1. the products of meiosis are haploid.
2. somatic cells do not enter into meiosis.
3. during meiosis, crossing over very rarely occurs between homologous
chromosomes.
4. the complete process of meiosis requires two rounds of cell division.
14.
In a higher eukaryote, how many functional sperm will be produced from one round of
meiosis in a healthy male?
1. one
2. two
3. three
4. four
15.
Regarding bivalents,
1. they form during metaphase II of meiosis.
2. they each contain one sex chromosome.
3. there are 2n of them produced in meiosis, where n = the haploid number of
chromosomes.
4. they each contain a total of four chromatids.
16.
What is the probability that in an organism with a haploid number of 12 an egg will be
formed that contains all 12 chromosomes whose centromeres were derived from paternal
homologs?
1. (1/12)2
2.(1/10)12
3. 212
4. None of the above.
17.
In each of Mendel's monohybrid crosses of pea plants, the trait that disappeared in the F1
generation but reappeared in the F2 generation
1. illustrated the principle of independent assortment.
2. was a recessive trait.
3. appeared in 3/4 of the plants in F2 generation.
4. None of the above.
18.
The chi-square test involves statistical comparison between observed versus expected
values. One generally determines degrees of freedom as
1. the number of categories being compared.
2. one less than the number of classes being compared.
3. one more than the number of classes being compared.
4. the sum of the two categories.
19.
A tall, violet plant is crossed with a dwarf, white plant and all of the F1 offspring are tall,
violet. The F1 plants are selfed to produce the F2 generation. What fraction of the F2 generation
would you expect to be tall, white? (Assume independent assortment.)
1. 1/4
2. 9/16
3. 3/16
4. 1/16
20.
The principle of independent assortment
1. explains the 3:1 ratio of phenotypes in the F2 generation of Mendel's dihybrid crosses.
2. states that a dihybrid cross is essentially equivalent to two independent,
simultaneous monohybrid crosses.
3. is due to random alignment of different chromosomes at metaphase II of meiosis.
4. none of the above.
21.
In the cross AaBbCcDd x AaBbCcDd, how many different phenotypes should appear
among the offspring? (Assume independent assortment, simple dominance/recessiveness for
each gene, and no epistasis or other gene interactions.)
1. 8
2. 27
3. 4
4. 16
22.
In a family of five children, what is the probability that the second born is a male?
1. 1/10
2. 1/2
3. 1/4
4. 1/32
23.
Red-green color blindness is X-linked recessive. A woman with normal color vision has
a father who is color-blind. The woman has a child with a man with normal color vision. Which
phenotype is NOT expected for the child?
1. color-blind female
2. color-blind male
3. noncolor-blind female
4. noncolor-blind male
24.
Red-green color blindness is X-linked recessive. MN blood type is determined by an
autosomal gene with two codominant alleles, LM and LN. A woman whose father was color-blind
has type MN blood. She is going to have a child with a man who has normal color vision and
type MN blood. What is the probability the child will be a boy, with normal color vision and
type M blood?
1. 1/4
2. 1/16
3. 1/32
4. 1/64
25.
A Barr body is
1. a gene on the X chromosome that is responsible for female development.
2. a patch of cells that has a phenotype different from surrounding cells because of
variable X inactivation.
3. an inactivated X chromosome, visible in the nucleus of a cell from a female
mammal.
4. an extra X chromosome in a cell that is the result of nondisjunction.
26.
What is the expected number of Barr bodies in an individual with the karyotype
XXXXYYY?
1. 1
2. 2
3. 3
4. 4
27.
The genotype XYY produces a
1. female in Drosophila and a female in humans.
2. female in Drosophila and a male in humans.
3. male in Drosophila and a male in humans.
4. male in Drosophila and a female in humans.
Use the following pedigree for questions 28-32:
I
2
1
3
4
II
1
2
3
4
5
III
1
28. Could the characteristic followed in the pedigree be caused by an autosomal dominant
disease? Why or why not?
1. Yes, all individuals fit the autosomal dominant inheritance pattern.
2. No, the offspring of I-1 and I-2 contradict an autosomal dominant inheritance.
3. No, the offspring of I-3 and I-4 contradict an autosomal dominant inheritance.
4. No, the offspring of II-3 and II-4 contradict an autosomal dominant inheritance.
29. If the pedigree is for an autosomal recessive characteristic, which individuals are definitely
heterozygous?
1. I-1, I-2, II-2, II-4 and II-5
2. I-1, I-2, I-4, III-1
3. I-1, I-2, II-4, II-5, III-1
4. II-2, II-4, II-5, II-3
30. Could the characteristics followed in the pedigree be caused by an X-linked recessive allele?
1. Yes, all individuals fit the X-linked recessive inheritance pattern.
2. No, the offspring of I-1 and I-2 contradict an X-linked recessive inheritance.
3. No, the offspring of I-3 and I-4 contradict an X-linked recessive inheritance.
4. No, the offspring of II-3 and II-4 contradict an X-linked recessive inheritance.
31. If the characteristic followed in the pedigree is autosomal recessive, what is III-1’s genotype?
1. either homozygous dominant or heterozygous
2. definitely heterozygous
3. definitely homozygous dominant
4. there’s really no good way to tell
32. If the characteristic in the pedigree is X-linked recessive allele, what is III-1’s genotype?
1. hemizygous for a dominant allele
2. hemizygous for a recessive allele
3. definitely heterozygous
4. definitely homozygous dominant
33.
With in incomplete dominance, a likely phenotypic ratio resulting from a monohybrid
cross would be:
1. 3:1
2. 1:2:2:4
3. 1:2:1
4. 9:3:3:1
34.
A condition in which one gene pair influences the expression of another gene pair is
called
1. codominance.
2. epistasis.
3. dominance.
4. recessiveness.
35.
Typical ratios resulting from epistatic interactions in dihybrid crosses would be:
1.
2.
3.
4.
9:3:3:1, 1:2:1
1:1:1:1, 1:4:6:4:1
9:3:4, 9:7
3:1, 1:1
36.
In a disputed parentage case, the child is blood type O while the mother is blood type B.
What blood type would exclude a male from being the father?
1. O
2. A
3. B
4. AB
37.
Consider a gene with alleles "B" and "b". Suppose that the homozygous recessive
genotype bb is lethal during embryonic development. In a cross between two heterozygotes, Bb
x Bb, what percentage of the living offspring should be BB?
1. 1/2
2. 1/3
3. 1/4
4. 2/3
38.
In “cytoplasmic inheritance,” the genes controlling a given trait are
1.
2.
3.
4.
39.
In “sex-influenced inheritance,”
1.
2.
3.
4.
40.
inherited from the mother and expressed in both males and females.
inherited from the mother and expressed only in females.
inherited from the father and expressed in both males and females.
inherited in the nuclear genome.
a trait can be expressed in one sex only.
a given genotype produces a different phenotype in males versus females.
a given trait is on the X chromosome.
fathers never pass the trait to sons.
In “genetic maternal effect,”
1.
2.
3.
4.
the mother’s behavior influences the phenotype of the offspring.
the phenotype of offspring is determined by the phenotype of the mother.
the genotype of offspring is determined by the phenotype of the mother.
the phenotype of an offspring is not determined by the offspring’s genotype.
THAT'S ALL!