Biol. 303 EXAM I 2/13/07
NAME____________________________
-------------------------------------------------------------------------------------------------------------------This exam consists of 40 multiple choice questions worth 2.5 points each. On the
separate testing form, please fill-in the single best choice for each question. Important -- fill-in
your student number and name on your answer sheet. Good luck!
-------------------------------------------------------------------------------------------------------------------1.
Eukaryotic cells differ from prokaryotic cells in that
1. prokaryotes do not have DNA.
2. only prokaryotes have a true nucleus.
3. only eukaryotic cells contain genetic material.
4. none of the above.
2.
If the haploid number of chromosomes for an organism is 48, then a diploid cell from this
organism contains how many pairs of homologous chromosomes?
1. 24
2. 12
3. 48
4. 96
3.
If a typical somatic cell has 32 chromosomes, how many chromosomes are expected in
each gamete of that organism?
1. 32
2. 0
3. 16
4. 64
4.
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.
5.
In a healthy female higher eukaryote, how many functional eggs will be produced from
one primary oocyte undergoing meiosis?
1. one
2. two
3. three
4. four
6.
In an organism with a diploid number of chromosomes equal to 52, how many bivalents
are expected to form during meiosis?
1.
2.
3.
4.
7.
52
26
13
104
The ant, Myrmecia pilosula, is found in Australia and is named bulldog because of
its aggressive behavior. It is particularly interesting because it carries all its genetic
information in a single pair of chromosomes. In other words, 2n =2. (Males are haploid
and have just one chromosome.) Which of the following figures would most likely
represent a correct configuration of chromosomes in a Metaphase I cell of a female?
1.
2.
3.
4.
8.
What is the outcome of synapsis, a significant event in meiosis?
1. side-by-side alignment of homologous chromosomes
2. chromosome movement to opposite poles
3. dyad formation
4. side by side alignment of nonhomologous chromosomes
9.
An allele is
1. a type of cell.
2. a dominant trait.
3. a form of a gene.
4. an imaginary concept.
10.
In each one of Mendel's dihybrid crosses,
1. partial dominance was observed.
2. the phenotypes in the F1 generation segregated in a 3:1 ratio.
3. three distinct phenotypes were observed in the F1 generation.
4. the phenotypes in the F2 generation segregated in a 9:3:3:1 ratio.
11.
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
12.
Regarding the cross in question 11 above, the most common genotype among the
offspring should occur at what frequency?
1. 1/4
2. 1/8
3. 1/2
4. 1/16
13.
Regarding the cross in question 11 above, how many distinct genotypes should appear
among the offspring?
1. 4
2. 16
3. 9
4. 8
14.
In tigers, a recessive allele causes a white tiger (virtual absence of fur pigmentation). If
two phenotypically normal tigers are mated and produce a white offspring, what percentage of all
their offspring is expected to be white?
1. 75%
2. 25%
3. 50%
4. about 66%
15.
Tight curly hair is caused by a dominant gene in humans. This trait is rare among
northern Europeans. If a curly-haired northern European marries a person with straight hair,
what proportion of their offspring would be expected to have curly hair?
1. 1/4 curly
2.100% curly
3. 3/4 curly
4. 1/2 curly
16.
A black guinea pig crossed with an albino guinea pig produced 5 black offspring. When
the albino was crossed with a second black one, 4 blacks and 3 albinos were obtained. What is
the best explanation for this genetic situation?
1. albino is recessive, black is dominant
2. albino and black are codominant
3. albino is dominant, black is incompletely dominant
4. albino is recessive, black is recessive
17.
Gray seed color in peas is dominant to white. Assume that Mendel conducted a series of
experiments where plants with gray seeds were crossed among themselves and the following
progeny were produced: 302 gray and 98 white. What is the most probable genotype of each
parent and what genotypic and phenotypic ratios are expected in the progeny? Assume the
following symbols: G= gray and g = white.
1. GG X
2. Gg X
3. gg X
4. Gg X
gg; genotypic = 3:1, phenotypic = 1:2:1
Gg; genotypic = 3:1, phenotypic = 9:3:3:1
Gg ; genotypic = 1:2, phenotypic = 3:1
Gg; genotypic = 1:2:1, phenotypic = 3:1
18.
The fundamental Mendelian process which involves the separation of contrasting genetic
elements into gametes is called
1. discontinuous variation.
2. independent assortment.
3. segregation.
4. dominance or recessiveness.
19.
What is the probability that in an organism with a haploid number of 10 that a sperm will
be formed that contains no chromosomes whose centromeres were derived from maternal
homologs?
1. (1/2)10
2.(1/10)2
3. 210
4. None of the above.
20.
What Mendel referred to as "unit factors" of inheritance are now referred to as:
1. genes.
2. nuclei.
3. sperm.
4. chromosomes.
21.
Consider the pedigree below for a rare trait:
The trait illustrated by the pedigree is most likely
1. sex-linked recessive.
2. sex-linked dominant.
3. autosomal recessive.
4. autosomal dominant.
22. The pedigree below shows the telltale signs of what kind of inheritance?
1.
2.
3.
4.
sex-linked recessive.
sex-linked dominant.
autosomal recessive.
Y-linked.
23.
In the cross AABbCc x AaBbCc, 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
24.
With 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
25.
A situation where there are more than two alternative forms of a given gene would be
called
1. multiple alleles
2. incomplete dominance
3. hemizygosity
4. codominance
26.
Hemizygosity would most likely be associated with which of the following?
1. X-linked inheritance
2. codominance
3. sex-limited inheritance
4. incomplete dominance
27.
A condition in which one gene pair influences the expression of another gene pair is
called
1. codominance.
2. epistasis.
3. dominance.
4. recessiveness.
28.
In a disputed parentage case, the child is blood type O while the mother is blood type A.
What blood type would exclude a male from being the father?
1. O
2. A
3. B
4. AB
29.
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
30.
When "reciprocal crosses" yield different results for the F1 and F2 generations, this is a
sign of
1. sex-linked inheritance.
2. y-linked inheritance.
3. the fact that Mendel's principles are false.
4. codominance.
31.
Color blindness is a recessive sex-linked trait. If a colorblind woman has children with a
colorblind man, then
1. each daughter has a 50% chance of being colorblind.
2. no sons or daughters will be colorblind.
3. each son has a 50% chance of being colorblind.
4. all sons and daughters will be colorblind.
32.
When two genes fail to assort independently, the term normally applied is
1. dominance and/or recessiveness
2. Mendelian inheritance
3. discontinuous inheritance
4. linkage
33.
Which statement is true?
1. double crossovers are usually more frequent than single crossovers along a given
interval of a chromosome.
2. single crossovers are usually more frequent than double crossovers along a given
interval of a chromosome.
3. double crossovers between homologous chromosomes are impossible.
4. only an even number of crossovers may occur during meiosis.
34.
Even when crossing over always occurs between two genes on the same chromosome, the
upper limit for recovery of recombinant gametes in the long run is:
1. 10%
2. 25%
3. 50%
4. 100%
35.
Examine the following data for crossing over among the alleles a b and c for three genes:
allele pair:
a,b
b,c
a,c
percent recombination
between the pair:
25
5
20
Based on this data, what is the order of the three genes on a genetic map?
1. a b c
2. a c b
3. c a b
4. there's no way to tell.
36.
Genetic distance within a given chromosome
1. cannot exceed 100 cM.
2. is measured in centiMorgans.
3. cannot be determined.
4. none of the above
37.
Assume that a cross is made between AaBb and aabb plants and the offspring fall into
approximately equal numbers of the following groups: AaBb, Aabb, aaBb, aabb. These results
are consistent with
1. independent assortment
2. incomplete dominance
3. hemizygosity
4. complete linkage
38.
Assume that a cross is made between AaBb and aabb plants and all the offspring are
either AaBb or aabb. These results are consistent with
1. incomplete dominance
2. independent assortment
3. complete linkage
4. codominance
39.
Assume that a cross is made between AaBb and aabb plants and the offspring occur in
the following numbers: 106 AaBb, 48 Aabb, 52 aaBb, 94 aabb. These results are consistent with
1. linkage with approximately 33 map units between the two gene loci
2. 100% recombination
3. linkage with 50% crossing over
4. independent assortment
40.
A female fruit fly heterozygous for three linked mutant alleles a,b,c, (genotype AaBbCc)
is crossed with a male fly that is homozygous recessive for all three mutant alleles. If the
phenotypes of the most common offspring are ABC and abc and the least common offspring are
aBC and Abc, then the order of the genes a b c on the chromosome is:
1. a b c
2. b a c
3. b c a
4. not enough information to tell.
That
wasn’t
too bad.
QUESTION NUMBER
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
CORRECT ANSWER
4
3
3
3
1
2
2
1
3
4
1
1
3
2
4
1
4
3
1
1
4
1
3
3
1
1
2
4
2
1
4
4
2
3
2
2
1
3
1
2