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100
Descent with modification is the best modern definition of what?
Evolution
100
Which mechanism produces variation for evolution by shuffling existing alleles?
Sexual reproduction
100
An earthquake decimates a ground-squirrel population, killing 98% of the squirrels. The surviving population
happens to have broader stripes, on average, than the initial population. If broadness of stripes is genetically
determined, what effect has the ground-squirrel population experienced during the earthquake?
a genetic bottleneck
100
Over time, the movement of people on Earth has steadily increased. This has altered the course of human
evolution by increasing ________.
Gene flow
200
When there is a change in allele frequencies in a population what is occurring?
Microevolution
200
Genetic drift produces variation for evolution when ________.
chance events cause allele frequencies to fluctuate unpredictably
200
The Dunkers are a religious group that moved from Germany to Pennsylvania in the mid-1700s. They do not
marry with members outside their own immediate community. Today, the Dunkers are genetically unique and
differ in gene frequencies, at many loci, from all other populations including those in their original homeland.
Which of the following mechanisms likely explains the genetic uniqueness of this population?
founder effect and genetic drift
200
No two people are genetically identical, except for identical twins. The main source of genetic variation among
humans is
the reshuffling of alleles in sexual reproduction.
300
Which of the following descriptions illustrates phenotype variation caused by environment?
When the diet of caterpillars changes their morphology.
300
Which Hardy-Weinberg condition is affected by population size?
genetic drift
300
In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of allele a is
0.1. What is the frequency of individuals with AA genotype?
0.81
300
what refers to the contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals
Relative fitness
400
What must be present in a population before natural selection can act upon the population?
Genetic Variation
400
What do small populations allow to occur?
Small populations allow gene frequencies to change by chance.
400
In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of allele a is
0.2. What is the frequency of individuals that are heterozygous for this allele?
0.32
400
What are the three modes of selection?
Directional selection favors individuals at one extreme end of the phenotypic range
Disruptive selection favors individuals at both extremes of the phenotypic range
Stabilizing selection favors intermediate variants and acts against extreme phenotypes
500
In the formula for determining a population's genotype frequencies, the "pq" in the term 2pq is necessary
because ________.
heterozygotes have two alleles
500
Homozygotes with two sickle-cell alleles are selected against because of mortality. However, heterozygotes for
sickle-cell allele experience little effects of sickle allele and are more likely to survive malaria. The net effect of
this exposure produced evolutionary change in areas where malaria is endemic by ________.
increasing sickle-cell allele frequency
500
In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of the allele a
is 0.3. What is the frequency of individuals that are homozygous for this allele?
0.09
500
What is this photo an example of?
Sexual dimorphism and sexual selection