MOLGEN500 Mod5(SA) 
lianchen 

Front  Back  
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 HardyWeinberg 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 HardyWeinberg 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.bellshaped
f.regression coefficient
g.relationship between variables
h.correlation coefficient

e.bellshaped
 
genetic variance:
a.additive, dominance, genic interaction
b.distribution around the mean
c.phenotype proportions
d.pleiotropy
e.bellshaped
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 HardyWeinberg 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.bellshaped
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 blueeyed and the population is in HardyWeinberg 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 6cm flowers, from a highly inbred strain, is crossed to a plant with 30cm flowers, also from a highly inbred strain. The F1 have 18cm flowers. F1 × F1 crosses yield F2 plants with flowers ranging from 6 to 30 cm in diameter, in approximately 4cm intervals (6, 10, 14, 18, 22, 26, 30).
Reference: Ref 241
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.bellshaped
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 HardyWeinberg 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 HardyWeinberg 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 diseasecausing 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.bellshaped
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.bellshaped
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 6cm flowers, from a highly inbred strain, is crossed to a plant with 30cm flowers, also from a highly inbred strain. The F1 have 18cm flowers. F1 × F1 crosses yield F2 plants with flowers ranging from 6 to 30 cm in diameter, in approximately 4cm intervals (6, 10, 14, 18, 22, 26, 30).
Reference: Ref 241
An 18cm F1 plant is crossed to a 6cm 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.bellshaped
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.bellshaped
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
 
