ch 25
If a population is in Hardy-Weinberg equilibrium, what is not an assumption that can be made about that population? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices
Allelic frequencies of the population are subject to natural selection
A population of rabbits was divided up based upon the color of their fur, represented by a single locus with two alleles (B for the dominant brown allele, and b for the recessive white allele): BB (brown fur) 100 Bb (brown fur) 88 bb (white fur) 25 Calculate the allelic frequencies of the fur color locus for this population of rabbits.
B = 0.68, b = 0.32 Correct! Allelic frequency is the number of one allele (2 × # of homozygotes + 1 × # of heterozygotes) divided by the total number of alleles (2 × # of individuals). The allelic frequency of B = (100 × 2) + (88)/(100 + 88 + 25) × 2
If you have data on genotype frequencies at a locus for a population, what steps would you follow to determine if these genotypes are in Hardy-Weinberg equilibrium? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices
Calculate allele frequencies from the observed genotype frequencies, use the allele frequencies to calculate the expected number of genotypes under Hardy-Weinberg equilibrium, and conduct a chi-square test. Correct! Allele frequencies are used to calculate the expected numbers of each genotype under Hardy-Weinberg equilibrium. The chi-square test allows you to statistically evaluate whether or not the two sets of numbers match.
Changes in a population's overall _____ lead to evolution of that population.
gene pool
which of the following will not increase genetic variation within a population? Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices
genetic drift
In a population of wild horses, individuals with genotypes RR, Rr and rr have on average 5, 10 and 7 offspring, respectively. What is the selection coefficient for heterozygotes?
0 Correct! The fitness (W) of the heterozygotes is the average number of offspring for heterozygotes divided by the average number of offspring produced by the most prolific genotype. Since the heterozygotes produce the most offspring, W = 10/10 = 1. The selection coefficient is then 1 - W, or 1 - 1 = 0.
You are studying a population of prairie dogs who have a unique spotting pattern on their fur. You have determined the genotypes for spotted and non-spotted fur as follows: Genotypes Number observed BB 75 Bb 210 bb 40 What are the frequencies of the genotypes BB, Bb and bb expected under Hardy-Weinberg equilibrium?
0.306, 0.494, 0.120
You are studying a population of prairie dogs who have a unique spotting pattern on their fur. You have determined the genotypes for spotted and non-spotted fur as follows: Genotypes Number observed BB 75 Bb 210 bb 40 If the frequency of the B allele equals p and the frequency of the b allele equals q, what is the frequency of the B allele?
0.553
If the frequency of a particular homozygous recessive disease in a population is 1 in 10,000, what percent of the population is a carrier of the disease?
2%
If the frequency of a particular homozygous recessive disease in a population is 1 in 10,000, what percent of the population is homozygous dominant for the wild-type trait?
98%
If variation of heritable traits is the basis of all evolution, which of the following would not contribute to the evolution of a population?
DNA mutations in somatic cells acquired during adulthood
Consider a population of inbreeding humans, in which the inbreeding coefficient is 0.6. At locus A, there are 215 individuals with genotype AA, 58 with Aa, and 190 with aa. How much will the frequency of heterozygotes decrease after an additional generation of mating?
Exactly! The correct answer is: 30% Correct! The genotypic frequency of heterozygotes will decrease by a factor of 2Fpq with each subsequent generation.
From a sample of individuals the following genotypes were counted for ABO blood types where IA, IB, and i represent different alleles: IAIA (A blood type) 28 IAIB (AB blood type) 10 IBIB(B blood type) 15 IBi (B blood type) 12 IAi (A blood type) 20 ii (O blood type) 15 Calculate the allele frequencies of the ABO blood group locus for this population.
IA = 0.43, IB= 0.26, I = 0.31 Correct! Allelic frequency is the number of one allele (2 × # of homozygotes + 1 × # of heterozygotes of each type) divided by the total number of alleles (2 × # of individuals). The allelic frequency of IA = (28 × 2) + (10 + 20) /(28 + 10 + 15 + 12 + 20 + 15) × 2
A _____ is a group of interbreeding, sexually reproducing individuals that have a common set of genes.
Mendelian population
_____ can introduce new harmful alleles into a population, while _____ will decrease their frequency.
Mutation; natural selection
A population of cats has the following genotypes for an X-linked coat-color trait (O for the dominant brown allele, o for the recessive orange allele): Brown homozygous females: 30 Brown heterozygous females: 75 Orange females: 10 Brown males: 50 Orange males: 65 What are the allele frequencies in this population?
O = 0.54, o = 0.46 Correct! O = [(30 × 2) + 75 + 50]/{[(30 + 75 + 10) × 2] + 50 + 65}, o = [(10 × 2) + 75 + 65]/{[(30 + 75 + 10) × 2] + 50 + 65}.
From the individuals in your genetics class, the following phenotypes and corresponding genotypes were counted for tasters versus non-tasters of the chemical compound phenylthiocarbamide (PTC), where P and p represent different alleles: PP (severe tasters) 11 Pp (mild tasters) 18 pp (non-tasters) 20 Calculate the genotypic frequencies of the PTC-taste locus for this population. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices
PP = 0.22, Pp = 0.37, pp = 0.41 Genotypic frequency is the number of individuals with a particular genotype divided by the total number of individuals. PP = 11/(11 + 18 + 20), Pp = 18/(11 + 18 + 20), pp = 20/(11 + 18 + 20).
Which of the following is not an assumption of populations exhibiting Hardy-Weinberg equilibrium for a given trait?
The population is undergoing natural selection.
What is a prediction of the Hardy-Weinberg law if the assumptions about the population is correct?
The population's allelic frequencies stabilize.
Genetic drift results in _____ within populations and _____ between populations.
allele frequency changes and loss of genetic variation; genetic divergence
Genetic rescue is when _____.
an inbred population's genetic variation is increased, usually through the introduction of new individuals
In which method of calculating allelic frequency would you not need to know the actual numbers of the different genotypes in the population?
calculating by genotypic frequencies
An individual who is the offspring of two closely related parents will likely have homozygous alleles identical by _____.
descent
True or false? A population in Hardy-Weinberg equilibrium is actively evolving.
fa;se
True or false? Although you can use either numbers of genotypes or frequencies of genotypes to calculated allelic frequencies for a single, somatic allele, you can only use numbers of genotypes to calculated allelic frequencies for X-linked loci and loci with multiple alleles.
false
True or false? An inbreeding population can be in Hardy-Weinberg equilibrium at any time.
false
True or false? When the only change in a population is mutations, change in allelic frequencies happens at a rapid pace.
false
The relative reproductive success of a genotype is known as _____.
fitness
Positive assortative mating for relatedness is also known as _____.
inbreeding
Population genetics makes use of _____, which are simple representations of a process that consists of only a few influential factors.
mathematical models
All genetic variants ultimately arise through _____.
mutation
Occasionally, an allele N1 (frequency = p) mutates to N2 (frequency = q). The rate at which the frequency of N2 changes in the population is a function of the _____.
mutation rate and frequency of N1 (p)
If the assumptions of the Hardy-Weinberg law are met, the genotype frequencies in a population will stabilize after _____ generation(s) of random mating.
one
The study of population genetics and the study of evolution are related for all of the following reasons, except _____.
population geneticists only study populations that are affected by artificial selection
A number of plants and animals regularly inbreed and are successful. What is one positive outcome of inbreeding for these populations?
preservation of co-adapted gene complexes
If humans engaged in negative assortative mating for height, who would short people preferentially mate with?
tall people
When a population is in Hardy-Weinberg equilibrium, the genotypic frequencies are determined by _____.
the allelic frequencies
Allelic frequency can be calculated from _____.
the numbers and frequencies of genotypes
True or false? In a mathematical model, the equation defines the way in which the variables influence the process. Please choose the correct answer from the following choices, and then select the submit answer button. Answer choices
true
True or false? Nonrandom mating alters the frequency of genotypes of a population, but not the frequency of alleles.
true
True or false? You can use the Hardy-Weinberg law to determine whether natural selection or other selection pressures are acting upon a population at any given time.
true