Chapter 27: Population genetics
A gene is present in the form of three alleles in a population, G, g1, and g2. If the frequency of the G allele is 0.6, and the frequency of the g1 allele is 0.2, then what is the frequency of the g2 allele?
0.2 The sum of the frequencies must equal 1.
In a population of frogs, a gene is found in two forms - D, and d. The numbers of individuals with different genotypes for that gene are 30 (DD), 18 (Dd), and 12 (dd). What is the frequency of the heterozygous genotype?
0.30
A gene is found in two forms in a population of plants. The two alleles are denoted as B, and b. You determine that the frequency of the B allele in this population is 0.2. If this population was in a Hardy-Weinberg equilibrium, calculate the probability of a heterozygote in the next generation.
0.32 Calculate 2pq for p=0.2 and q=1-p
You are studying a bird population and a gene that has 2 alleles, A, which is found at a frequency of 0.4, and a, which is found at a frequency of 0.6. If this population was in Hardy-Weinberg equilibrium, what would be the probability of the genotype aa in the next generation?
0.36 The frequency of the aa genotype is q2= 0.6 x 0.6.
Consider a population, for which you know the allele composition of three genes. Gene A has three alleles in the following proportions: A1 - 34.4%, A2 - 30%, A3 - 35.6%. Gene B has two alleles in the following proportions: B1 - 67.1%, B2 - 32.9%. Gene C has two alleles in the following proportions: C1 - 99.2%, C2 - 0.8%. Which of those genes is(are) polymorphic?
A and B only
Which of the following correctly defines a population of sexually reproducing species for the purposes of population genetics? Multiple choice question. A group of individuals that occupy the same area and can interbreed with each other A group of individuals that live in the same general area and their gene pool A group of individuals that occupy the same area and compete for the same resources
A group of individuals that occupy the same area and can interbreed with each other
Consider the following types of changes in DNA: a deletion of part of a gene (A); a duplication of a region in a gene (B); a replacement of one nucleotide with a different one (C). Which of those changes can cause polymorphisms in a population?
A, B, and C
You are studying a very rare disease, which affects only 1 in 40,000 individuals. The disease is caused by a recessive allele, such that only individuals with homozygous recessive genotypes are affected. What is the expected frequency of heterozygous carriers in this population?
About 1% In this problem q2=1/40,000. Use this information to calculate q and p. The frequency of heterozygous carriers is 2pq.
Consider a population of cheetahs, inhabiting a protected area in Africa. In 2012, there were 112 cheetahs in this population. During that year, 60 of those animals reproduced and 48 new cubs were born. What constitutes the gene pool of the new generation made of those 48 new cubs?
All of the alleles of all the genes that were passed from the 60 parents to the 48 new cubs
Consider a population of a hypothetical animal, whose fur color is determined by a single gene, called Col. From the list below choose all conditions that must be met in order for this population to be in Hardy-Weinberg equilibrium for the Col gene. Multiple select question. Animals in the population mate randomly, regardless of their genotype for the Col gene No new mutations in the Col gene No new mutations in any gene No natural selection Low to moderate levels of genetic drift
Animals in the population mate randomly, regardless of their genotype for the Col gene No new mutations in the Col gene No natural selection
You are studying a rare disease, which affects 1 out of 10000 individuals. The disease is caused by a gene with two alleles: D, and d. Individuals with a dd genotype are affected, while individuals with a Dd phenotype are unaffected carriers. What is the expected frequency of unaffected carriers in the population, assuming this gene is in Hardy-Weinberg equilibrium?
Approximately 2% In this problem q2=1/10000. Use this information to calculate q and p. The frequency of heterozygous carriers is 2pq.
If a population is in Hardy-Weinberg equilibrium for a gene with two alleles (G and g), and the frequency of the g allele is very low, we can predict that most of the organisms in this population will have the _____ genotype.
GG
Natural populations are dynamic entities. From the list below choose features of populations that can change from one generation to the next. Multiple select question. Geographic location Species diversity Size Genetic composition
Geographic location Size Genetic composition
Which of the following are factors that can cause a change in the size of a population from one generation to the next? Multiple select question. Predators Natural disasters A new mutation Diseases
Predators Natural disasters Diseases
What is the most common type of polymorphism found in natural populations, including human populations?
SNPs
Which of the following describes a situation, in which the predominant genotype in a population in Hardy-Weinberg equilibrium is the heterozygote? Assume that the gene of interest has only two alleles: G, and g.
The allele frequencies of both G and g are intermediate in value.
How is the allele frequency of a population calculated?
The number of copies of the allele in the population is divided by the total number of all the alleles for the same gene in the population.
How can we calculate the frequency of a specific genotype in a population?
The number of individuals with this genotype in the population is divided by the total number of individuals in the population.
Which of the following are conditions that must be met in order for a population to be in Hardy-Weinberg equilibrium for a specific gene of interest? Multiple select question. The population must be large enough so that no genetic drift is occurring. All of the different genotypes (with respect to the gene of interest) must have equal reproductive success (no selection). No new mutations should be appearing in the gene of interest. Immigration and emigration rates must be equal, resulting in no net movement of organisms.
The population must be large enough so that no genetic drift is occurring. All of the different genotypes (with respect to the gene of interest) must have equal reproductive success (no selection). No new mutations should be appearing in the gene of interest.
The _____ _____ of a population consists of all of the alleles of every gene in all of the individuals of that population.
allele frequency
A population would be described as being in ______ if a high chi-square value is obtained when testing whether the allele and genotype frequencies are in Hardy-Weinberg equilibrium.
disequilibrium
When the hypothesis that the allele and genotype frequencies are in Hardy-Weinberg equilibrium is rejected, it can be stated that the population is in
disequilibrium
The Hardy-Weinberg equilibrium is a mathematical expression which predicts that, when certain requirements are met, the allele and genotype frequencies of a gene in a population ______.
do not change over the course of many generations
The Hardy -Weinberg equilibrium is used as a null hypothesis, i.e., if a population is in Hardy-Weinberg equilibrium, then ______.
evolutionary change is not occurring in this population
Population genetics is concerned with the ______.
extent of genetic variation within a group of individuals
In order to derive the Hardy-Weinberg equation, the two scientists assumed that ______ population's gene pool.
gametes are independently chosen at random from the
Consider a population and a gene that has two alleles in this population, designated as D and d. If you divide the number of individuals with the genotype DD by the total number of individuals in the population, you will calculate the ______.
genotype frequency of the DD genotype
A large, healthy, natural population typically exhibits a ______ level of SNPs.
high
The change in a population's gene pool from one generation to the next is known as ______.
microevolution
Which of the following is an accurate depiction of the Hardy-Weinberg equation for a gene with two alleles?
p2 + 2pq + q2 = 1
In population genetics, a gene that exists as two or more alleles in a population is a(n) ______ gene, while one that exists predominantly as a single allele is a(n) ______ gene.
polymorphic; monomorphic
Most of the traits in a healthy natural population exhibit some level of variation, or _____, that is, they are found in two or more forms.
polymorphism
When scientists study populations, they typically observe high levels of variation in many of the traits that characterize a species. In genetics, variations in traits at the population level are known as ______.
polymorphisms
In genetics, a _____ of a sexually reproducing species consists of a group of individuals of that species, which occupy the same region, and can successfully interbreed with each other.
population
The genetics field that is concerned with the extent of genetic variation within a group of individuals and changes in that variation over time is _____ genetics.
population
A change in one nucleotide in a gene is also known as a _____ -nucleotide _____ , or, SNP.
single-nucleotide polymorphism (SNP)
Microevolution is best described as ______.
the change in a population's gene pool from generation to generation
In a population of lizards, a gene is found in two forms, B, and b. The number of animals with the three possible genotypes for this gene is as follows: BB - 24; Bb - 42; bb - 9. What is the frequency of the B allele in this population?
0.6
You are studying a population and a gene within that population with two alleles, M and m. After determining the genotypes of all the individuals in the population you calculate the observed and expected numbers of individuals for the three genotypes as follows. Observed individuals: MM - 200; Mm 123; mm - 14. Expected individuals: MM - 202; Mm - 117; mm - 17. What is the Chi-square value calculated based on these observations?
0.86 (O-E)^2 / E
The sum of the frequencies of all of the alleles of a particular gene in a population is always
1
You are studying a population and a gene within that population with two alleles, H and h. After determining the genotypes of all the individuals in the population you calculate the observed and expected numbers of individuals for the three genotypes as follows. Observed individuals: HH - 87; Hh - 145; hh - 68. Expected individuals: HH - 75; Hh - 150; hh - 75. What is the Chi-square value calculated based on these observations?
2.74
Consider a population and a gene that has two alleles in this population, designated as E and e. If you divide the number of all the copies of the e allele in the population by the total number of copies of both alleles (E and e) in the population, you will calculate the ______.
allele frequency of the e allele
