Download Final Exam Genetics Fall 2011

Final Exam
Genetics
Fall 2011
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1) Because of the mechanism of sex determination, males of many species can be neither homozygous nor
heterozygous. Such males are said to be ________.
A) complementary
B) hemizygous
C) dominant
D) recessive
E) none of the above
1) _____
2) Assume that a man who carries an X-linked gene has children. Assuming normal meiosis and random
combination of gametes, the man would pass this gene to
A) half of his daughters.
B) half of his sons.
C) all of his sons.
D) all of his daughters.
E) all of his children.
2) _____
3) If a typical somatic cell has 64 chromosomes, how many chromosomes are expected in each gamete of
that organism?
A) 64
B) 128
C) 16
D) 8
E) 32
3) _____
4) What term is given to the total genetic information carried by all members of a population?
A) gene pool
B) breeding unit
C) race
D) genome
E) chromosome complement
4) _____
5) When an organism gains or loses one or more chromosomes but not a complete
haploid set, the condition is known as ________.
A) triploidy
B) polyploidy
C) euploidy
D) aneuploidy
E) trisomy
5) _____
6) One form of hemophilia is caused by a sex-linked recessive gene. Assume that a man with hemophilia
marries a phenotypically normal woman whose father had hemophilia. What is the probability that their
first son will have hemophilia?
A) 1/4
B) 1/8
C) 3/4
D) 1/2
E) 1/16
6) _____
7) In small isolated populations, gene frequencies can fluctuate considerably. The term that applies to this
circumstance is
A) natural selection.
B) stabilizing selection.
C) genetic isolation.
D) allelic separation.
E) genetic drift.
7) _____
8) In a population of 100 individuals, 49% are of the NN blood type. What percentage is expected to be MN
assuming Hardy-Weinberg equilibrium conditions?
A) 42%
B) 51%
C) 21%
D) 9%
E) insufficient information to answer this question
8) _____
9) Which of the following is NOT true with regard to the IGF2/H19 locus
A) It is a good example of genomic inprinting
B) Methylation blocks both the insulator and the H19 promoter region
C) H19 is active if it is inherited from the mother
D) IGF2 is inactive if it is inherited from the father
E) None of the above. ALL of the statements are true
9) _____
10) Polydactyly is expressed when an individual has extra fingers and/or toes. Assume that a man with six
fingers on each hand and six toes on each foot marries a woman with a normal number of digits. Having
extra digits is caused by a dominant allele. The couple has a son with normal hands and feet, but the
couple's second child has extra digits. What is the probability that their next child will have polydactyly?
A) 1/2
B) 1/32
C) 3/4
D) 7/16
E) 1/8
10) _____
11) During interphase of the cell cycle
A) DNA recombines.
B) DNA content essentially doubles.
C) RNA replicates.
D) sister chromatids move to opposite poles.
E) the nuclear membrane disappears.
11) _____
12) Which protein class directly controls many of the metabolic reactions within a cell?
A) hydrophilic proteins
B) repressor proteins
C) operator proteins
D) structural proteins
E) enzymes
12) _____
13) What is the name given to the three bases in a messenger RNA that bind to the anticodon of tRNA to
specify an amino acid placement in a protein?
A) protein
B) codon
C) cistron
D) rho
E) anti-anticodon
13) _____
14) Albinism is an autosomal recessive trait in humans. Assume that there are 100 albinos (aa) in a
population of 1 million. How many individuals would be expected to be homozygous normal (AA)
under equilibrium conditions?
A) 10,000
B) 19,800
C) 100
D) 980,100
E) 999,900
14) _____
15) Klinefelter syndrome in humans, which leads to underdeveloped testes and sterility, is caused by which
chromosomal condition?
A) 47, 21+
B) 47, XYY
C) 45, X
D) triploidy
E) 47, XXY
15) _____
16) If 15% of the nitrogenous bases in a sample of DNA from a particular organism is thymine, what
percentage should be cytosine?
A) 35%
B) 70%
C) 40%
D) 30%
E) 15%
16) _____
17) Mutant versions of genes that are normally involved in promoting the cell cycle are known as
A) proto-oncogenes.
B) tumor suppressors.
C) oncogenes.
D) malignant genes.
E) attenuators.
17) _____
18) Trisomy 21, or Down syndrome, occurs when there is a normal diploid chromosomal complement but
one (extra) chromosome 21. While there is reduced fertility in both sexes, females have higher fertility
than males. Van Dyke et al. (1995. Down Syndrome Research and Practice 3(2):65—69) summarize data
involving children born of Down syndrome individuals. Given the fact that conceptuses with 48
chromosomes (four #21 chromosomes) are not likely to survive early development, what percentage of
surviving offspring would be expected to have Down syndrome if both parents have Down syndrome?
A) One-half of the surviving offspring would be expected to have Down syndrome.
B) Two-thirds of the surviving offspring would be expected to have Down syndrome.
C) None of the surviving offspring would be expected to have Down syndrome.
D) One-third of the surviving offspring would be expected to have Down syndrome.
E) All the children would be expected to have Down syndrome.
18) _____
19) The basic structure of a nucleotide includes the following components:
A) base, sugar, and phosphate.
B) mRNA, rRNA, and tRNA.
C) tryptophan and leucine.
D) amino acids.
E) phosphorus and sulfur.
19) _____
20) A recessive allele in tigers causes the white tiger. If two normally pigmented tigers are mated and
produce a white offspring, what percentage of their remaining offspring would be expected to have
normal pigmentation?
A) about 90%
B) 50%
C) 25%
D) about 66%
E) 75%
20) _____
21) Introns are known to contain termination codons (UAA, UGA, or UAG), yet these codons do not
interrupt the coding of a particular protein. Why?
A) Introns are removed from mRNA before translation.
B) These triplets cause frameshift mutations, but not termination.
C) More than one termination codon is needed to stop translation.
D) Exons are spliced out of mRNA before translation.
E) UAA, UGA, and UAG are initiator codons, not termination codons.
21) _____
22) An intron is a section of
A) carbohydrate that serves as a signal for RNA transport.
B) protein that is clipped out post-translationally.
C) RNA that is removed during RNA processing.
D) DNA that is removed during DNA processing.
E) transfer RNA that binds to the anticodon.
22) _____
23) In an analysis of the nucleotide composition of double-stranded DNA to see which bases are equivalent
in concentration, which of the following would be true?
A) A = C
B) A = G and C = T
C) A + C = G + T
D) A + T = G + C
E) Both B and C are true.
23) _____
24) Trisomy 21, or Down syndrome, occurs when there is a normal diploid chromosomal complement but
one (extra) chromosome 21. While there is reduced fertility in both sexes, females have higher fertility
than males. Van Dyke et al. (1995. Down Syndrome Research and Practice 3(2):65—69) summarize data
involving children born of Down syndrome individuals. Assume that children are born to a female with
Down syndrome and a normal 46-chromosome male. What proportion of the offspring would be
expected to have Down syndrome?
A) One half of the offspring would be expected to have Down syndrome.
B) Two-thirds of the offspring would be expected to have Down syndrome.
C) One-third of the offspring would be expected to have Down syndrome.
D) None of the offspring would be expected to have Down syndrome.
E) All the children would be expected to have Down syndrome.
24) _____
25) Consanguineous (blood relatives) marriages leads to
A) inbreeding.
B) gene pools.
C) an increase in heterozygosity as a rule.
D) sibling species.
E) hybrid vigor.
25) _____
26) A class of mutations that results in multiple contiguous (side-by-side) amino acid changes in proteins is
probably caused by the following type of mutation:
A) transversion.
B) recombinant.
C) frameshift.
D) base analog.
E) transition.
26) _____
27) Nutritional mutations can be defined as
A) those mutations caused by site-specific mutagenesis.
B) those mutations that do not allow an organism to grow on minimal medium, but do allow the
organism to grow on complete medium.
C) those mutations that change the composition of the medium.
D) those mutations belonging to the group called prototrophs.
E) all strains that are not auxotrophic.
27) _____
28) The genetic material DNA consists of basic subunits called
A) mitochondria.
B) centrioles.
C) nucleotides.
D) lysosomes.
E) none of the above
28) _____
29) There are a number of mechanisms that operate to maintain genetic diversity in a population. Why?
A) Greater genetic diversity increases the chances of haploidy.
B) Diversity may better adapt a population to inevitable changes in the environment.
C) Homozygosity is an evolutionary advantage.
D) Genetic diversity helps populations avoid diploidy.
E) Diversity leads to inbreeding advantages.
29) _____
30) The discipline within evolutionary biology that studies changes in allele frequencies is known as
A) population genetics.
B) consanguineous.
C) hybrid vigor.
D) genetics.
E) cytogenetics.
30) _____
31) The immediate product of transcription is
A) a carbohydrate.
B) an amino acid.
C) a protein.
D) a phospholipid.
E) RNA.
31) _____
32) Assume that you are told that a particular organism, Drosophila, has the XO chromosome complement.
You are also told that the autosomal complement is a normal 2n. You know that in humans the XO
complement is female determining. Would you be correct in assuming that the Drosophila sex for XO is
also female?
A) No, the chromosomal basis for sex determination in Drosophila and humans is very different.
B) Yes, because sex determination in humans and insects is essentially the same.
C) Yes, the presence of an X chromosome determines a female in both organisms.
D) No, sex determination in Drosophila is dependent on presence or absence of the Y chromosome.
E) No, it takes two X chromosomes to produce a female in humans and a Y chromosome to produce
a male in Drosophila.
32) _____
33) The mosaic of red and white eye facets in D. melanogaster caused by positional effect variegation (PEV) is
due to
A) Variation in the stopping point of the spread of heterochromatin
B) The acetylation of nucleosomes near the promoter for the red eye gene.
C) Genomic inprinting
D) Random inactivation of one X chromosome into a barr body
E) None of the above
33) _____
34) The genetic code is said to be triplet, meaning that
A) there are three bases in mRNA that code for an amino acid.
B) there are three amino acids per base in mRNA.
C) there may be three ways in which an amino acid may terminate a chain.
D) there are three "nonsense" triplets.
E) none of the above
34) _____
35) In humans, the genetic basis for determining the sex "male" is accomplished by the presence of ________.
A) one X chromosome
B) a balance between the number of X chromosomes and the number of haploid
sets of autosomes
C) a portion of the Y chromosome
D) high levels of estrogen
E) multiple alleles scattered throughout the autosomes
35) _____
36) In many species, there are two representatives of each chromosome. In such species, the characteristic
number of chromosomes is called the ________ number. It is usually symbolized as ________.
A) haploid, 2n
B) diploid, n
C) diploid, 2n
D) haploid, n
E) none of the above
36) _____
37) Two formal terms used to describe categories of mutational nucleotide substitutions in DNA are called
A) transversions and transitions.
B) sense and antisense.
C) euchromatic and heterochromatic.
D) base analogs and frameshift.
E) error prone and spontaneous.
37) _____
38) Assume that 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 black and 3 albino offspring were produced. What genetic
explanation would apply to these data?
A) Albino = recessive; black = dominant..
B) Albino = dominant; black = incompletely dominant.
C) Albino and black = codominant
D) Albino = recessive; black = recessive
E) none of the above
38) _____
39) Considering the structure of double-stranded DNA, what kinds of bonds hold one complementary
strand to the other?
A) covalent
B) hydrogen
C) ionic
D) van der Waals
E) hydrophobic and hydrophilic
39) _____
40) Hemizygosity would most likely be associated with which of the following?
A) X-linked inheritance
B) sex-limited inheritance
C) incomplete dominance
D) trihybrid crosses
E) codominance
40) _____
41) What types of phenotypic ratios are likely to occur in crosses when dealing with a single gene pair
where all the genotypic combinations are of equal viability?
A) 12:3:1, 9:7
B) 1:2:1, 3:1
C) 2:3, 1:2
D) 1:4:6:4:1, 1:1:1:1
E) 9:3:3:1, 27:9:9:9:3:3:3:1
41) _____
42) With incomplete dominance, a likely ratio resulting from a monohybrid cross would be ________.
A) 1:2:2:4
B) 9:3:3:1
C) 1:2:1
D) 3:1
E) 3:3
42) _____
43) A recessive gene for red-green color blindness is located on the X chromosome in humans. Assume that
a woman with normal vision (her father is color-blind) marries a color-blind male. What is the
likelihood (give a percentage) that this couple's first son will be color-blind?
A) 100%
B) 50%
C) 0%
D) 75%
E) 25%
43) _____
44) For an individual with the XXY chromosomal composition, the expected number of Barr bodies in
interphase cells is
A) two
B) three
C) zero
D) one
E) variable
44) _____
45) The primary structure of a protein is determined by
A) hydrogen bonds formed between the components of the peptide linkage.
B) pleated sheets.
C) the sequence of amino acids.
D) a series of helical domains.
E) covalent bonds formed between fibroin residues.
45) _____
46) One form of hemophilia is caused by a sex-linked recessive gene. Assume that a man with hemophilia
marries a phenotypically normal woman whose father had hemophilia. What is the probability that they
will have a daughter with hemophilia? (Note: In this problem you must include the probability of having
a daughter in your computation of the final probability.)
A) 1/16
B) 1/4
C) 1/8
D) 1/2
E) 3/4
46) _____
47) In a certain breed of dog, the alleles B and b determine black and brown coats respectively. However,
the allele Q of a gene on a separate chromosome is epistatic to the B and b color alleles resulting in a
gray coat (q has no effect on color). If animals of genotype B/b ; Q/q are intercrossed, what phenotypic
ratio is expected in the progeny?
A) 9 gray, 3 brown, 4 black
B) 1 black, 2 gray, 1 brown
C) 9 black, 6 brown, 1 gray
D) 9 black, 4 gray, 3 brown
E) 12 gray, 3 black, 1 brown
48) In sweet peas the allele C is needed for color expression (c results in no color i.e. white). The precise
color expressed is determined by the alleles R (red) and r (blue). A cross between certain red and blue
plants resulted in progeny as follows:
3/8 red
3/8 blue
1/4 white
What were the genotypes of the plants crossed?
A) C/C ; R/R x C/c ; R/r
B) C/c ; r/r x C/C ; R/r
C) C/c ; R/r x C/c ; R/r
D) C/c ; R/r x C/c ; r/r
E) c/c ; R/r x C/c ; R/r
49) In Drosophila the eye color peach is determined by an autosomal recessive allele p. On another
chromosome the autosomal recessive s suppresses peach, restoring the wild-type red eye color. When
two pure-breeding red strains 1 and 2 are intercrossed, the F1 is also red. However when the F1 is
backcrossed to strain 1, the progeny show 3/4 red and 1/4 peach flies. The genotype of the strain 1
must have been
A) p+/p+ ; s+/s+
B) p+/p ; s/s
C) p/p ; s+/s+
D) p+/p ; s+/s
E) p/p ; s/s
50) In mice the allele for color expression is C (c = albino). Another gene determines color (B = black and
b = brown). Yet another gene modifies the amount of color so that D = normal amount of color and d =
dilute (milky) color. Two mice that are C/c ; B/b ; D/d are mated. What proportion of progeny will be
dilute brown (assume complete dominance at each locus)?
A) 9/16
B) 3/64
C) 9/64
D) 1/4
E) 3/16
51) Drosophila eyes are normally red. Several purple-eyed strains have been isolated as spontaneous
variants (mutants) and the purple phenotype has been shown to be inherited as a Mendelian autosomal
recessive in each case. To investigate allelism between these different purple mutations, two purpleeyed pure strains were crossed. If the purple mutations are in different genes (that is they are not
allelic), the F1 is expected to be
A) all red
B) all purple
C) 3/4 red, 1/4 purple
D) 1/2 red, 1/2 purple
E) 1/4 red, 3/4 purple
52) In Drosophila, segmentation genes function in a sequential manner in the following order:
A) gap, segment-polarity, pair-rule.
B) pair-rule, transdeterminal, gap.
C) transdeterminal, gap, pair-rule.
D) gap, pair-rule, segment-polarity.
E) segmentational, helical, spherical.
53) Mutations that eliminate a contiguous region in the Drosophila embryo's segmentation pattern are due
to the effect of
A) homeodomains.
B) gap genes.
C) compartment genes.
D) linkage genes.
E) segment genes.
54) The anterior to posterior gradient of HB-M (Hunchback) protein is controlled by…
a. Tethering nos (nanos) mRNA posteriorly in the oocyte
b. Tethering hb (hunchback) mRNA anteriorly
c. Tethering bcd (bicoid) mRNA anteriorly
d. Releasing HB-M protein across the intercellular space from “nurse cells” anteriorly
e. Tethering HB-M protein anteriorly in the oocyte
55) The process by which totipotent stem cells become more and more specialized is called….
a. Specialization
b. Canalzation
c. Fate refinement
d. Fate maintenance
e. None of the above
56) Genes that respond to products produced by the gap genes in order to determine the specific
characteristics a segment will have are called…
a. Cardinal genes
b. Homeotic genes
c. Pair rule genes
d. Segment polarity genes
e. Maternal effects genes
57)
Compounds A, B, and C are found in the same biochemical pathway in corn. Two homozygous plants
are crossed; one made only compound A and the other made only compound B. The F1 of these two
homozygotes made A, B, and C.
The F2 plants were of the following types and frequencies:
9/16 were able to make A, B, and C;
3/16 were able to make only A;
3/16 were able to make only B;
1/16 made none of the three compounds.
Which pathway below best describes the relation of A, B, and C?
A)
B)
C)
D)
E)
58)
In Neurospora, a linear biochemical pathway synthesizes an amino acid Z. E1, E2, and E3 are
enzymes that catalyze the three reactions.
E1 E2 E3
WXY Z
Null mutants for the enzyme E2 gene will grow on minimal medium supplemented with compounds
A) W or X
B) Y or Z
C) W or X or Y or Z
D) Z only
E) W only
59) In the absence of arabinose, the araC protein represses the ara operon by binding to
A) araI
B) araO
C) araI and araO
D) araI and araA
E) araO and araA
60) RNA polymerase binds to
A) Repressor gene
B) Promoter
C) Operator
D) Permease gene
E) Lactose
61)
When two genes fail to assort independently, the term normally applied is
A)
B)
C)
D)
E)
62)
discontinuous inheritance
dominance and/or recessiveness
tetrad analysis
linkage
Mendelian inheritance
In order for proper development to take place in eukaryotes it is necessary to…
a. Create a population of identical cells
b. Give a group of cells polarity (asymmetry)
c. Create a mechanism for cell-cell communication
d. Develop ways to “fix” the fate of a cell once it is determined
e. All of the above
63) In drosophila the dorsal ventral axis is established by…
a. Tethering mRNA for the spz (spaetzle) gene ventrally in the oocyte
b. Tethering mRNA for the dl (dorsal) gene dorsally in the oocyte
c. Having follicle cells along the dorsal side of the syncytium release active DL protein to diffuse across
the intercellular space
d. Having follicle cells along the ventral side of the syncytium release SPZ protein to diffuse across the
intercellular space
e. All of the above
64) Which of the following is NOT true regarding the formation of the germ line in animals
a. In D. melanogaster it is determined by the sperm entry point
b. It is a good example of a binary fate decision
c. It is determined by the distribution of P granules in C. elegans
d. It is determined by the distribution of Polar Granules in D. melanogaster
e. The process results in the formation of Pole Cells in D. melanogaster
65) Which of the following is NOT true with regard to the mechanisms of epigenetic gene regulation
a. It can be accomplished by moving the nucleosome down a DNA strand
b. It can be accomplished by moving the nucleosome from one DNA molecule to another
c. It can be accomplished by restructuring the nucleosome
d. It can be accomplished by “methylation” of cytosine
e. None of the above. ALL of the above statements are true
66) What is the general function of the consensus sequence called the GC box? What is its sequence?
A)
B)
C)
D)
E)
terminator; CAAT
promoter; CAAT
terminator; GGGCGG
attenuator; GGGCGG
promoter; GGGCGG
67) Two modular elements that appear upstream from RNA polymerase II transcription start sites
a. enhancers and telomeres
b. microsatellites and transposons.
c. TATA and CAAT.
d. rDNA and nucleolar organizers.
e. TTAA and CCTT.
68)
E. coli is able to use foods other than glucose in the absence of available glucose, because
falling levels of glucose cause an increase of
A) cAMP
B) CAP
C) lactase
D) glu operons
E) tRNA
69)
Enhancers are
A) proteins located adjacent to promoters
B) distant sites where regulatory proteins bind
C) expediters of RNA polymerase capture
D) proteins that bind with repressors, deactivating them
E) a bacterial form of promoters
70)
Proteins
A)
B)
C)
D)
E)
71)
that block the passage of RNA polymerase are called:
operons
activators
repressors
enhancers
promoters
In the DVD “Ghost in you Genes” Angelman’s syndrome is caused by a deletion on…
a. The paternal chromosome 15
b. The maternal chromosome 15
c. Chromosome 15 of either sex
d. The X chromosome
e. The Y chromosome
72)
Hereditary information can be passed from one generation through…
a. Changes in the DNA code
b. Changes in the degree of methylation of the DNA
c. Changes in the histone packaging of DNA
d. Epigentic changes
e. All of the above
73)
Expression of the genes you possess could be affected by….
a. Maternal care or lack thereof
b. The diet of your grandparent (feast or famine)
c. Pesticides in the environment
d. Smoking
e. All of the above
74)
Your DNA code (sequence of nucleotides) can be changed readily by…
a. Common chemicals in the environment
b. Caffeine
c. UV radiation
d. The quality of your nutrition
e. All of the above
75)
Positive assortative mating…
a. Is the opposite of inbreeding
b. Is the preference for individuals with a particular similar phenotype
c. Can be brought about by dispersal of animals before they reach maturity
d. Can be brought about by self incompatibility (sterility)
e. All of the above