Final Exam - Previous Exam Questions
In a quantitative genetics study of genes influencing body mass in mice, two true-breeding mouse strains that differed sharply in body mass were crossed to produce an F1. The expected genetic variance involved in body mass in the F1 population is expected to be: -0 -greater than 0 but less than that of either parental strain -significantly greater than either parental strain
0
Red green colorblindness is an X-linked recessive disorder that occurs in 10% of males of European descent. Therefore, the frequency of the colorblindness allele is: -0.25 -0.01 -0.1 -<0.001 -0.5
0.1
Although Mendel is considered the father of genetics, genetics as a modern science really got its start in _______ when three researchers independently published findings that essentially confirmed Mendel's conclusions. -1954 -1900 -1924 -1866 -1837 -1888
1900
A minimum of _______ genes (gene, not alleles) are involved in crosses that demonstrate epistasis. -4 -3 -2 -8
2
A eukaryotic cell enters the G1 phase of the cell cycle with 20 chromosomes and 20 pg of DNA. During the G2 phase of the cell cycle, this same cell will have _____ chromosomes and _____ pg of DNA. -20 chromosomes; 10 pg DNA -20 chromosomes; 20 pg DNA -20 chromosomes; 40 pg DNA -20 chromosomes; 0 pg DNA -40 chromosomes; 40 pg DNA -10 chromosomes; 10 pg DNA
20 chromosomes; 40 pg DNA
Species I has 2n = 24 chromosomes. How many chromosomes will be found per cell in a monosomic individual of this species? -25 -48 -23 -12 -24 -36
23
Species I has 2n = 16 chromosomes. How many chromosomes will be found per cell in an autotriploid of this species? -15 -8 -24 -14 -32 -17
24
A diploid cell in the G2 phase of the cell cycle and just about to enter into meiosis contains 100 pg of DNA in its chromosomes. At the end of meiosis II, each daughter cell will contain _______ pg of DNA in its chromosomes. -25 -100 -50 -12.5
25
An individual that develops as an outcome of mitochondrial DNA replacement therapy has a genome composed of DNA derived from _________ individuals. -1 -2 -3 -4
3
Species I has 2n = 18 chromosomes and species II has 2n = 12 chromosomes. How many chromosomes would be present in an allotetraploid derived from these species? -18 -24 -12 -30 -60
30
If you performed a test cross for gene mapping and found that 25% of the offspring were recombinant types, then a reasonable estimate for the true map distance between these genes would be: -37 cM -25 cM -15 cM
37 cM
The human opsin and rhodopsin genes are linked on chromosome 6. Imagine that you measure the genetic map distance between these genes in males and determine this to be 3 cM. Assuming a two-fold higher rate of recombination in females relative to males, what map distance would you find if you repeated this study in females? -1.5 cM -6 cM -3 cM
6 cM
Imagine a quantitative genetic model in which each gene has two alleles that interact additively, with one allele adding nothing to the trait value and the other allele adding one unit to the trait value. Furthermore, in this model there is no influence of environmental variation on phenotype and each possible phenotype can be distinguished from any other. In this hypothetical system, how many different phenotypes would be observed if four genes influenced the trait? -9 -8 -10 -18 -7
9
Imagine a study of heritability that begins with two true-breeding strains that differ sharply in a trait. These strains are crossed to produce an F1. The F1 is then intercrossed to produce an F2. The environmental conditions experienced by individuals in all generations is controlled to be as similar as possible. Which of the following is expected? -The phenotypic variance of the F1 will equal the phenotypic variance of the F2 -The phenotypic variance of the F1 will be greater than the phenotypic variance of the F2 -The phenotypic variance of the F2 will be greater than the phenotypic variance of the F1 -The difference in phenotypic variance between the F1 and the average of the two inbred parental populations estimates the environmental variance
The phenotypic variance of the F2 will be greater than the phenotypic variance of the F1
Assuming a fixed rate of mutation, under mutation/selection balance, the equilibrium frequency of a harmful allele is expected to be highest if the allele is: -an incompletely dominant -a completely recessive allele -a completely dominant allele -the form of dominance is immaterial
a completely recessive allele
Functioning ribosomes are essential for life. Given this, if you wanted to study the function of the ribosome by finding as many mutations as possible that affect the ribosome's operation, the type of mutation you should look for is: -an incompletely dominant mutation -a pleiotropic mutation -a lethal mutation -a conditional mutation -a recessive mutation
a conditional mutation
A selection limit is often due to: -an increase in environmental variance -a decrease in additive genetic variance (VA) -an increase in total genetic variance (VG) -a decrease in total genetic variance (VG) -an increase in phenotypic variance (VP)
a decrease in additive genetic variance (VA)
Taken together, the facts that DNA has strands that are arranged in antiparallel orientation and that DNA can only be synthesized in the 5' to 3' direction predict the existence of: -a discontinuous stand of DNA -the need to DNA gyrase -the need for DNA helicase -the need for multiple origins of replication -the need for three differnt bacterial DNA polymerases
a discontinuous stand of DNA
Which of the following is plausible for a norm-of-reaction plot of environmental value (x-axis) versus phenotypic value (y-axis) for a conditional allele? -a straight line with a negative slope -a flat horizontal line -a flat horizontal line at low environmental values with a sharp downturn beginning at a particular environmental value -a vertical line -a straight line with a positive slope
a flat horizontal line at low environmental values with a sharp downturn beginning at a particular environmental value
On a low fat diet, mice with the A1A1 genotype gain more weight than mice with the A2A2 genotype. On a high fat diet, mice with the A1A1 genotype gain less weight than mice with the A2A2 genotype. These results indicate: -pleiotropy -near zero narrow-sense heritability -a genotype-environment interaction -a limited response to selection -near perfect (near a value of 1.0) narrow-sense heritability that approaches 1.0
a genotype-environment interaction
Homozygosity for the completely recessive Tay-Sachs allele leads to death before reaching reproductive age. Given this, the frequency of the Tay-Sachs allele is expected to decrease at the fastest rate in: -a population in which the fitness of the Tay-Sachs homozygotes was 1.0 -a population with a low frequency of the Tay-Sachs allele -a population with a high frequency of the Tay-Sachs allele -a large population
a population with a high frequency of the Tay-Sachs allele
A plot of the number of genes versus genome size that includes a wide variety of eukaryotic organisms is predicted to yield: -a straight line of positive slope formed by tightly-clustered data points -a scatter of points that would yield a regression line with a slope near 0 -a straight line of negative slope formed by tightly-clustered data points
a scatter of points that would yield a regression line with a slope near 0
A triploid variety of a crop plant can be generated by crossing: -a pentaploid variety of the plant with a monoploid (haploid) variety of the plant -a tetraploid variety of the plant with a diploid variety of the plant -a tetrasomic variety of the plant with a disomic variety of the plant -a tetrasomic variety of the plant with a monosomic variety of the plant -a trisomic variety of the plant with a nullisomic variety of the plant
a tetraploid variety of the plant with a diploid variety of the plant
The SRY gene of placental mammals codes for: -a signal receptor -a transcription factor -a signal protein
a transcription factor
Many of the genes needed for mitochondrial function: -are located in the nuclear genome -are located in the mitochondrial genome -are located exclusively in the mitochondrial genome
are located in the nuclear genome
Common units for physical maps are: -centimorgans (cM) -base pairs (bp) -map units (mu)
base pairs
Imbalanced gene dosage is likely to cause the problems associated with all the following EXCEPT: -aneuploidy -chromosome duplications -chromosome inversions -chromosome deletions
chromosome inversions
All new dominant alleles that arise through mutation quickly increase in frequency in subsequent generations. -complete dominance with spots dominant to dots -codominance -incomplete dominance -complete dominance with dots dominant to spots
codominance
Phenylkenonuria (PKU) is a recessive genetic disorder that is due to the inability to metabolize the amino acid phenylalanine. Fortunately, the disease symptoms associated with homozygosity for the the PKU disease allele can be be prevented if homozygotes are placed on a low phenylalanine diet. Therefore, the allele associated with PKU is: -multifactorial -conditional -dominant lethal -polygenic
conidtional
______ + (dNMP)n → (dNMP)n+1 + PPi -
dNTP
The relative risk of homozygosity due to inbreeding is the ratio of the frequency of homozygosity with inbreeding to the frequency of homozygosity with random mating. Imagine that the frequency of an allele, say A1, increases within a population while the strength of inbreeding remains constant. In this situation, the relative risk of homozygosity for A1 due to inbreeding will ______ as the frequency of the A1 allele increases. -decrease -increase -remain the same -may go up or down depending on the dominance relationship between A1 and any other alleles of the A gene
decrease
Which of the following is true concerning gene interaction and epistasis? -gene interaction occurs when genes at two or more loci work together to control two or more different phenotypes -gene interaction is a special form of epistasis -different forms of epistasis involving two genes can result in modified versions of the 9:3:3:1 dihybrid phenotypic ratio -few traits are the result of gene interaction
different forms of epistasis involving two genes can result in modified versions of the 9:3:3:1 dihybrid phenotypic ratio
The traits that Mendel studied were____ traits. -epistatic -non-discrete -discontinuous -quantitative -pleiotropic
discontinuous
When considering haploinsufficiency, the mutant allele is expected to behave as a ______ allele. -codominant -polygenic -recessive -dominant
dominant
Many chromosome structural changes begin with: -nondisjunction of chromosomes at meiosis II -double-stranded breaks in DNA -nondisjunction of chromosomes at meiosis I -nondisjunction of chromosomes at either meiosis I or meiosis II -errors during transcription
double-stranded breaks in DNA
Most pseudogenes arise from: -non-reciprocal translocations -duplication and divergence -inversion heterozygosity -reciprocal translocations -deletion heterozygosity
duplication and divergence
Classic Turner syndrome is associated with an X0 aneuploid karyotype. In rare cases, Turner syndrome occurs in people who are 45X/46XY genetic mosaics. In these rare cases, the event that led to this form of aneuploidy likely occurred: -during meiosis I of spermatogenesis (sperm development) -during meiosis II of oogenesis (egg development) -during mitosis early in development of a male embryo -during meiosis I of oogenesis (egg development) -during meiosis II of spermatogenesis (sperm development) -during mitosis early in development of a female embryo
during mitosis early in development of a male embryo
The probability of fixation for a particular allele due to genetic drift is: -equal to the square root of the initial allele -equal to the square of the initial allele frequency -is independent of the initial allele frequency -equal to the final frequency of the allele -equal to the initial frequency of the allele
equal to the initial frequency of the allele
A polygenic trait is a trait that is determined by one gene with many different alleles. true or false?
false
A sex-influenced trait is a trait that is expressed in one sex but not the other. true or false?
false
All new dominant alleles that arise through mutation quickly increase in frequency in subsequent generations. true or false?
false
Cytosine and 5-methyl cytosine possess different base-pairing properties. true or false?
false
Distances on both genetic maps and physical maps are based on the frequency of recombination between pairs of genes. true or false?
false
Dominant alleles of a gene are always more common than recessive alleles of a gene. true or false?
false
For a genetic marker to be useful, for example, in genomewide association studies, there must be an organism-level phenotype associated with each allele of the genetic marker. true or false?
false
Humans have an exceptionally large eukaryotic genome. true or false?
false
IQ measured in adults has a narrow sense heritability of 0.7 - 0.8. Based on this, it can be concluded that 70% - 80% of a particular adult's IQ score is due to the person's genotype for alleles that act in an additive manner. true or false?
false
Imagine two human populations, both with high narrow sense heritability for adult body weight. One population has an average adult weight of 64 kg and the other population has an average adult weight of 78 kg. From this information, it is clear that that there are genetic differences contributing to the difference in adult body weight between these populations. true or false?
false
In Drosophila, one autosomal allele that determines gray body color is completely dominant to another allele for yellow body color. Therefore, allele for gray body color is expected to be completely dominant to the allele for yellow body color for all other traits influenced by this gene. true or false?
false
In all vertebrates, females are the homogametic sex and males are the heterogametic sex. true or false?
false
Mendel's principles of segregation and independent assortment apply to the vast majority of species in existence on Earth today. true or false?
false
Modern molecular studies support Sturtevant's hypothesis that the frequency of crossing over is constant at all points along a chromosome. true or false?
false
Most genome-wide association studies report finding one or two genetic variants that account for almost all the variation (for example, developing or not developing a particular disease) in whatever phenotype is being investigated. true or false?
false
One of the strongest lines of evidence for the bacteria origin of mitochondria is that mitochondria can be grown and maintained with relative ease outside of eukaryotic cells. true or false?
false
Over many cell divisions, replicative segregation of chloroplasts in cells that are heteroplasmic is likely to lead to a population of cells with a very similar mixture of chloroplast genotypes. true or false?
false
Pleiotropy occurs when one trait is influenced by many different genes. true or false?
false
Roughly half the cells in a woman lack the paternal copy of the X chromosome and the other half of the cells lack the maternal copy of the X chromosome. true or false?
false
The chromosome theory of inheritance was based on the observations that chromosomes contain DNA and that genes are composed of DNA. true or false?
false
The term "homologous chromosomes" means that the chromosomes are identical in their size, shape, and DNA sequence. true or false?
false
The process of gene duplication and divergence produces: -gene families -pericentric chromosome inversion heterozygosity -reciprocal gene translocations -Robersonian translocations -paracentric chromosome inversion heterozygosity -haploinsufficiency
gene families
What process works to slow the genetic divergence of separate subpopulations? -gene flow -mutation -genetic drift -natural selection -inbreeding
gene flow
Deletion heterozygosity often results in: -non-reciprocal translocations -haploinsuffciency -monosomy -reciprocal translocations -uniparental disomy -diparental disomy
haploinsuffciency
In mammals, Y linked genes are: -heterozygous -hemizygous -homozygous
hemizygous
Imagine studying two sets of nucleosomes. In the first set, there is about 150 bp of DNA tightly associated with the histone proteins of the nucleosome core. In the second set of nucleosomes, there is about 167 bp of DNA associated with the histone proteins of the nucleosome core. The most likely explanation of this difference is: -CenH3 is present in the first set of nucleosomes, but absent from the second set -CenH3 is present in the second set of nucleosomes, but absent from the first set -the first set of nucleosomes is being held at a higher temperature than the second set of nucleosomes -histone H1 is present in the first set of nucleosomes, but absent from the second set -histone H1 is present in the second set of nucleosomes, but absent from the first set
histone H1 is present in the second set of nucleosomes, but absent from the first set
The human lactase gene is autosomal and encodes an enzyme that is secreted into the small intestine to break down the sugar lactose. Imagine that there are two alleles of the lactase gene, one a wild type allele that encodes active enzyme, and the other a loss-of-function allele that fails to produce any enzyme. Focusing on the phenotype of the amount of lactase enzyme present in the small intestine, what type of dominance is predicted for these two alleles? -complete dominance with the wild type allele dominant to the mutant allele -incomplete dominance -codominance -complete dominance with the mutant allele dominant to the wild type allele
incomplete dominance
Hoxd13 is an important regulatory protein that acts in the nuclei of animal cells. A loss-of-function allele of the Hoxd13 gene is likely to be __________ to the functional allele of the gene. -codominant -recessive -incompletely dominant -incompletely penetrant
incompletely dominant
A discrete trait that is controlled by one gene with two alleles can be converted into a continuous trait by: -increasing the genotypic variance associated with each genotype -increasing the phenotypic variance associated with each genotype -decreasing the genotypic variance associated with each genotype -decreasing the phenotypic variance associated with each genotype
increasing the phenotypic variance associated with each genotype
Which of the following is critical for the formation of secondary structures in RNA? -3' to 5' polarity -antiparallel alignment of strands from different RNA molecules -5' to 3' polarity -intramolecular complementarity between nitrogenous bases
intramolecular complementarity between nitrogenous bases
DNA at the centromeres of multicellular eukaryotes: -is non protein-coding and has a conserved (similar) sequence across species -is protein-coding and does NOT have a conserved (similar) sequence across species -is protein-coding and has a conserved (similar) sequence across species -is non-coding and does NOT have a conserved (similar) sequence across species
is non-coding and does NOT have a conserved (similar) sequence across species
Mutation is a critically important force of evolution because: -it reduces the genetic diversity within a population -it exerts powerful selective pressures -it is the source of new alleles in a species -it causes rapid fluctuations in allele frequency between generations
it is the source of new alleles in a species
Mitotic aneuploidy can result from detachment of a chromosome from a spindle fiber during anaphase. In this case, the expectation is that of the two daughter cells, one will be ______ and the other will be _______. -diploid; trisomic -diploid; triploid -diploid; diploid -monosomic; diploi -monosomic; trisomic
monosomic; diploid
A trait that is influenced by many genes and by the environment is a _______ trait. -polygenic -multifactorial -pleiotropic -discontinuous -phenocopy
multifactorial
Which of the following typically accounts for a correlated genetic response that limits the response to selection? -loss of additive genetic variance -pleiotropy -a decrease in environmental variance -an increase in environmental variance -loss of total genetic variance
pleiotropy
A likely function of t-loop DNA is to: -serve as a template for RNA polymerases -create euchromatin -provide an internal template for the enzyme that catalyzes the synthesis of repetitive DNA sequences at the ends of chromosomes -prevent the ends of chromosomes from being recognized as substrates for DNA repair enzymes
prevent the ends of chromosomes from being recognized as substrates for DNA repair enzymes
When using a Punnett square, once entries to the tops and sides of the square have been completed, filling in the blank central cells of the square represents the biological process or processes of: -segregation -segregation and independent assortment -random fertilization -segregation, independent assortment, and random fertilization -independent assortment
random fertilization
Male-limited precocious puberty is an autosomal dominant trait that is expressed only in males. Therefore, male-limited precocious puberty is a ______ trait. -sex-limited -sex-influenced -sex-linked -Y-linked -X-linked
sex-limited
One seriously considered hypothesis for the rarity of mitochondrial heteroplasmy is: -that a bottleneck for mitochondria occurs during oogenesis or early development -that there is a frequent loss of homoplasmy in early development -the maternal inheritance of mitochondrial traits -the high rate of mutation of mitochondrial genes
that a bottleneck for mitochondria occurs during oogenesis or early development
Imagine that you discover an E. coli mutant with the following phenotype: In one section of a daughter DNA molecule produced from replication of a parent molecule, the newly synthesized DNA is present as a long continuous strand, but in the corresponding section of the other daughter DNA molecule, the newly synthesized DNA is present in short (~ 1000 nucleotide) pieces. What gene is most likely altered by mutation in this mutant E. coli strain? -the DNA polymerase III gene -the DNA helicase gene -the DNA ligase gene -the primase gene -the topoisomerase gene
the DNA ligase gene
The formation of a fertile allopolyploid typically involves: -the type of chromosome doubling seen in autopolyploid formation -the type of chromosome reduction seen in the formation of a fertile autopolyploid -hybridization between two related species that leads in one step to the formation of a fertile allopolyploid
the type of chromosome doubling seen in autopolyploid formation
Imagine a population that begins with a significant amount of heterozygosity. This population goes through multiple generations of inbreeding, but does not show any evidence of inbreeding depression. This could occur if: -there were few harmful recessive alleles in the gene pool (the entire set of alleles for this population) -the inbreeding coefficient was near 1.0 -there was a low rate of mutation that slowed the production of harmful alleles -there was a high rate of mutation resulting in the generation of recessive alleles
there were few harmful recessive alleles in the gene pool (the entire set of alleles for this population)
According to the orignal Lyon hypothesis, an XO woman (a woman with only one X chromosome) should have a normal phenotype. true or false?
true
Along a chromosome, the same strand of DNA serves as a template for the leading strand in some regions and serves as a template for the lagging strand in other regions. true or false?
true
Genomewide association studies examine many individuals to look for associations between a trait of interest and one or more genetic markers such as single nucleotide polymorphisms. true or false?
true
In almost all cases, when a fertile allopolyploid plant forms, the allopolyploid is a new species. true or false?
true
In humans, chromosome 21, the chromosome associated with Down syndrome, is NOT especially prone to undergoing nondisjunction during meiosis. true or false?
true
Mitosis can occur in a diploid or haploid cell. In contrast, meiosis can occur beginning with a diploid cell but not beginning with a haploid cell. true or false?
true
One explanation for incomplete penetrance of a genotype is that there are environmental differences experienced by different individuals who share a genotype at a particular locus. true or false?
true
One explanation for variable expressivity of a particular genotype is that many phenotypes are controlled by more than one gene. true or false?
true
Over multiple generations, inbreeding leads to most individuals in the inbred population having identical homozygous genotypes at autosomal loci. true or false?
true
The division of organisms as prokaryotic or eukaryotic does NOT reflect the evolutionary relationships of the major divisions of life. true or false?
true
The frequency of an allele can be determined accurately if the frequency of each genotype is known. However, the frequency of a genotype cannot always be determined accurately if the frequency of each allele is known. true or false?
true
