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MOLGEN500 Mod5(SA)
lianchen

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negative directional selection: a.Allele frequencies become more similar across populations. b.Generation of new alleles changes allele frequencies very slowly. c.Alleles may disappear from the population simply by chance. d.Allele frequencies do not change. e.The mean trait value decreases from one generation to another.       


The mean trait value decreases from one generation to another


population bottleneck: a.Allele frequencies become more similar across populations. b.Generation of new alleles changes allele frequencies very slowly. c.Alleles may disappear from the population simply by chance. d.Allele frequencies do not change. e.The mean trait value decreases from one generation to another.       


Alleles may disappear from the population simply by chance


Total phenotypic variance can be decomposed into all but one of these components: genetic–environment interaction variance. genetic variance.       environmental variance. Heritability


Heritability


Which of the following polymorphisms is the most efficient for use in population genetics studies? Amino acid sequence polymorphisms Restriction site variation Chromosomal polymorphisms Complete sequence variation Variable number of tandem repeats  


Complete sequence variation


To establish that evolution by natural selection is operating in a population, one must demonstrate variability for a trait, heritability of that trait, differential reproductive success based on that trait, and: continuous change in the environment. progress. random mating. increased complexity of the organism. nothing else.


nothing else.


______________ can cause the same genotype to produce a range of potential phenotypes. Epistasis The inbreeding coefficient Hybrid vigor Environmental effects Heritability


Environmental effects


The heterozygote genotype frequency term for a gene with two alternate alleles A (frequency of p) and a (frequency of q) in the Hardy-Weinberg equation is: p2 q2 2pq (p+q) P+2pq+q2


2pq


gene flow between two island populations: a.Allele frequencies become more similar across populations. b.Generation of new alleles changes allele frequencies very slowly. c.Alleles may disappear from the population simply by chance. d.Allele frequencies do not change. e.The mean trait value decreases from one generation to another.      


a.Allele frequencies become more similar across populations.


genetic drift: a.Allele frequencies become more similar across populations. b.Generation of new alleles changes allele frequencies very slowly. c.Alleles may disappear from the population simply by chance. d.Allele frequencies do not change. e.The mean trait value decreases from one generation to another.      


c.Alleles may disappear from the population simply by chance.


Mutation: a.Allele frequencies become more similar across populations. b.Generation of new alleles changes allele frequencies very slowly. c.Alleles may disappear from the population simply by chance. d.Allele frequencies do not change. e.The mean trait value decreases from one generation to another.       


b.Generation of new alleles changes allele frequencies very slowly.


Human racial differences are produced by A)        multiple genes that affect several traits. B)        a single gene that affects skin color. C)        cultural factors as well as multiple genes that affect several traits. D)        multiple genes that affect skin color.


C)        cultural factors as well as multiple genes that affect several traits.


Any change in a population from Hardy-Weinberg equilibrium can be defined as ______. mutation genetic equilibrium migration evolution natural selection


evolution


QTL mapping requires all of the following except: genetic markers. offspring. a genetic map. a controlled cross. an estimate of homozygosity in the population.


an estimate of homozygosity in the population.


A Mendelian population is defined by individuals interbreeding. inbreeding. evolving. living in close proximity. migrating.


interbreeding.


Which of the following is the fastest way for an enzyme to respond to changing conditions in the cell? A)        altering the enzyme's activity by allostearic effectors (activators or inhibitors) B)        changing the enzyme's compartmentalization or location in the cell C)        covalently modifying the enzyme in the cell (by phosphorylation) D)        controlling the synthesis or degradation of the enzyme in the cell


A)        altering the enzyme's activity by allostearic effectors (activators or inhibitors)


normal distribution a.additive, dominance, genic interaction b.distribution around the mean c.phenotype proportions d.pleiotropy e.bell-shaped f.regression coefficient g.relationship between variables h.correlation coefficient


e.bell-shaped


genetic variance: a.additive, dominance, genic interaction b.distribution around the mean c.phenotype proportions d.pleiotropy e.bell-shaped f.regression coefficient g.relationship between variables h.correlation coefficient 


a.additive, dominance, genic interaction


A gene or a trait is said to be polymorphic if: one form exists in the population. more that one form exists in the population. the allele frequency is ~50:50 for each gene or trait. the allele frequency of one trait is dominant over all others. one allele occurs at a frequency of less than 1%


more that one form exists in the population.


Population genetics is concerned with: how genes produce proteins. how genes confer relative reproductive success on the individuals. whether allele frequencies are changing over time. how genes interact with one another. (b) and (c) above.


(b) and (c) above.


In a normal distribution, 99% of the measurements fall within 1% of the mean. 5% of the mean. plus or minus one standard deviation of the mean. plus or minus two standard deviations of the mean. plus or minus three standard deviations of the mean.


plus or minus three standard deviations of the mean.


Two highly inbred tobacco plants are crossed. One has dark green leaves. The other has yellow leaves. The F1 have light green leaves. Five hundred progeny from F1 × F1 crosses are analyzed. Their leaves show continuous variation in color, but none has dark green or yellow leaves. What do these data suggest about the number of genes determining this trait? There are 2 genes that determine this trait. There are 3 genes that determine this trait. There are 4 genes that determine this trait. There are more than 4 genes that determine this trait.


There are more than 4 genes that determine this trait.


In a tropical human population in Hardy-Weinberg equilibrium for an autosomal locus determining presence/absence of pigment in the skin, the frequency of albinism (aa) is 1 in 10,000. The frequency of heterozygotes is approximately: 1 in 50 1 in 100 1 in 1000 1 in 75 1 in 25


1 in 50


Inbreeding in populations that are normally outbreeding leads to which of the following? A smaller population A higher rate of mutation A higher rate of genetic drift More individuals affected by rare diseases An increase in the frequency of heterozygotes


More individuals affected by rare diseases


Covariance: a.additive, dominance, genic interaction b.distribution around the mean c.phenotype proportions d.pleiotropy e.bell-shaped f.regression coefficient g.relationship between variables h.correlation coefficient


h.correlation coefficient


Mutation: a.All genetic information within a Mendelian population b.The mean trait value decreases from one generation to another c.Any change in allele frequencies within a population d.Probability of alleles being identical by descent e.Alleles may disappear from the population simply by chance f.Movement of genes g.Generation of new alleles


g.Generation of new alleles


The probability that two alleles are identical by descent is the __. a. coalescent b. inbreeding coefficient c. panmictic constant d. outcrossing rate e. relatedness


b. inbreeding coefficient


If 64% of the people in a population are blue-eyed and the population is in Hardy-Weinberg equilibrium, what is the percentage of heterozygotes in the population? 32% 36% 16% 20% It cannot be determined from these data.


32%


Which of the following is a concern of population genetics? How the cell copies its DNA How many people have color blindness in Utah How proteins fold under different pH conditions What causes sickle cell anemia? Why is cancer a difficult disease to treat?


How many people have color blindness in Utah


Which of the following is NOT a feature of Darwin's theory of natural selection? A)              A population adapts to its environment due to the variable reproductive success of individuals. B)         There is no heritable variation among individuals. C)         Individuals with poor fitness never produce offspring. D)         A and B E)         B and C


E)         B and C


Flower diameter in sunflowers is a quantitative trait. A plant with 6-cm flowers, from a highly inbred strain, is crossed to a plant with 30-cm flowers, also from a highly inbred strain. The F1 have 18-cm flowers. F1 × F1 crosses yield F2 plants with flowers ranging from 6 to 30 cm in diameter, in approximately 4-cm intervals (6, 10, 14, 18, 22, 26, 30). Reference: Ref 24-1 The number of different genes influencing flower diameter in this plant is 3. 4. 5. 6. 7.


3.


Which statement is true regarding heritability and continuous variation? Heritability measures the degree to which genes determine phenotype. As the number of gene loci that affect a trait increases, the proportion of extreme version of the trait also increases. The total variance used to calculate heritability measures all the variance in a population. A heritability value of 0.8% of the total variance is due to differences in the environment. A low heritability score means that genes are less influential than environment in determining phenotypic variation.


A low heritability score means that genes are less influential than environment in determining phenotypic variation.


Regression: a.additive, dominance, genic interaction b.distribution around the mean c.phenotype proportions d.pleiotropy e.bell-shaped f.regression coefficient g.relationship between variables h.correlation coefficient


g.relationship between variables


Inbreeding coefficient: a.All genetic information within a Mendelian population b.The mean trait value decreases from one generation to another c.Any change in allele frequencies within a population d.Probability of alleles being identical by descent e.Alleles may disappear from the population simply by chance f.Movement of genes g.Generation of new alleles


d.Probability of alleles being identical by descent


Human albinism is an autosomal recessive trait. Suppose that you find a village in the Andes where 1/4 of the population is albino. If the population size is 1000 and the population is in Hardy-Weinberg equilibrium with respect to this trait, how many individuals are expected to be heterozygotes? 50 250 300 500 750


500


Which of the following is NOT an example of nonrandom mating? positive assortative mating inbreeding outbreeding panmixis negative assortative mating  


panmixis


In this figure, we have plotted the time to maturity at a range of temperatures for three different genotypes. What concept does this figure illustrate?     a norm of reaction genotype by environment interactions genotypic variation phenotypic variation all of the above


all of the above


Evolution occurs: only through natural selection. only when the environment is changing. only via natural selection, genetic drift, migration, or mutation. only via natural selection, genetic drift, migration, or mutation. by altering physical traits but not behavioral traits.


only via natural selection, genetic drift, migration, or mutation.


In a population in Hardy-Weinberg equilibrium, what will be the proportion of matings between homozygotes? p2 + 2pq P4 p4 + q4 p4 + q4 + 2p2q2 4p2q2


p4 + q4 + 2p2q2


Which of the following is NOT an explanation as to why dominant disease-causing genes exist in populations? A)        The genes exert their effects late in life, beyond reproductive age. B)        Despite the genes' effects, individuals stay healthy enough to reproduce. C)        The genes are masked and therefore are passed only through carriers. D)        The genes may be the result of new mutations.


C)        The genes are masked and therefore are passed only through carriers.


Evolution: a.All genetic information within a Mendelian population b.The mean trait value decreases from one generation to another c.Any change in allele frequencies within a population d.Probability of alleles being identical by descent e.Alleles may disappear from the population simply by chance f.Movement of genes g.Generation of new alleles


c.Any change in allele frequencies within a population


A measure of the dispersion of a continuous distribution.


variance


In a human population, the genotype frequencies at one locus are 0.5 AA, 0.4 Aa, and 0.1 aa. The frequency of the A allele is: 0.20 0.32 0.50 0.70 0.90


0.70


variance: a.additive, dominance, genic interaction b.distribution around the mean c.phenotype proportions d.pleiotropy e.bell-shaped f.regression coefficient g.relationship between variables h.correlation coefficient


b.distribution around the mean


gene pool: a.All genetic information within a Mendelian population b.The mean trait value decreases from one generation to another c.Any change in allele frequencies within a population d.Probability of alleles being identical by descent e.Alleles may disappear from the population simply by chance f.Movement of genes g.Generation of new alleles


a.All genetic information within a Mendelian population


Genetic correlation a.additive, dominance, genic interaction b.distribution around the mean c.phenotype proportions d.pleiotropy e.bell-shaped f.regression coefficient g.relationship between variables h.correlation coefficient


d.pleiotropy


Which of the following evolutionary forces does NOT change allele frequencies? nonrandom mating mutation selection drift migration


nonrandom mating


Distributions A and B in the figure below have   the same mean and the same variance. different means and different variances. the same mean, but different variances. different means, but the same variance.


different means and different variances.


Flower diameter in sunflowers is a quantitative trait. A plant with 6-cm flowers, from a highly inbred strain, is crossed to a plant with 30-cm flowers, also from a highly inbred strain. The F1 have 18-cm flowers. F1 × F1 crosses yield F2 plants with flowers ranging from 6 to 30 cm in diameter, in approximately 4-cm intervals (6, 10, 14, 18, 22, 26, 30). Reference: Ref 24-1 An 18-cm F1 plant is crossed to a 6-cm plant. What is the probability of an offspring with one additive allele, if all genes that influence this trait are unlinked? 1/3 1/4 1/6 3/8 1/16


3/8


Which of the following statistical term is a not measure of central tendency? The Mean The Mode The Median Correlation All of the above


Correlation


If mating occurs solely between relatives, eventually what will happen to the population? It will become completely heterozygous. It will remain in equilibrium. It will become polymorphic for all shared traits. It will become completely homozygous. The individuals in the population will have more dominant alleles.


It will become completely homozygous.


Slope: a.additive, dominance, genic interaction b.distribution around the mean c.phenotype proportions d.pleiotropy e.bell-shaped f.regression coefficient g.relationship between variables h.correlation coefficient


h.correlation coefficient


Knowing the ___________ of a trait has great practical importance because it allows statistical predictions regarding the phenotypes of offspring to be made on the basis of the parent's _____________. a. variance b. inbreeding coefficient c. phenotype d. heritability e. genotype


heritability, phenotype


Rapid changes in allelic frequencies by __ take place in populations that are __. a. mutation b. evolving c. inbred d. small e. genetic drift


genetic drift, small


The cumulative contribution made by all the genes that contribute to a quantitative trait.


additive effect


Migration tends to __genetic variation between subpopulations and __ genetic variation within each subpopulation. a. increase b. not change c. reduce d. standardize e. invert


reduce, increase


What effect does mutation have on genetic variation?


It increases or creates it.


Frequency distribution: a.additive, dominance, genic interaction b.distribution around the mean c.phenotype proportions d.pleiotropy e.bell-shaped f.regression coefficient g.relationship between variables h.correlation coefficient


c.phenotype proportions


migration: a.All genetic information within a Mendelian population b.The mean trait value decreases from one generation to another c.Any change in allele frequencies within a population d.Probability of alleles being identical by descent e.Alleles may disappear from the population simply by chance f.Movement of genes g.Generation of new alleles


f.Movement of genes


The continuous distribution of quantitative traits is attributed to the fact that traits are influenced both by ______________ and by _____________ factors. a. environmental b. dominance c. measurement error d. many loci e. human error


many loci, environmental


A major difference between Mendelian and quantitative traits is in _______________ small differences between average phenotypes compared to differences between individuals within genotypes large differences between average phenotypes compared to differences between individuals within genotypes that statistical properties of Mendelian traits are better understood that statistical properties of quantitative traits are better understood there are no differences between them


small differences between average phenotypes compared to differences between individuals within genotypes