Chapter 23: Population Genetics (Book Questions) Flashcards
(49 cards)
The study of genes and genotypes in a population is called ___________ ___________
Population genetics
The _________ __________ of a population consists of all of the alleles for every gene in the population.
Gene pool
In a population, only individuals who ________ contribute to the gene pool of the next generation.
reproduce, breed, or procreate
Geographic isolation can divide a species into discrete populations because ______.
Multiple choice question.
it prevents natural selection from acting on the populations
it prevents the populations from exchanging alleles
it causes different mutations to occur in the separated populations
it prevents the populations from exchanging alleles
Some genetic changes make some individuals in a population become better suited to their environment and therefore more likely to survive and reproduce. This phenomenon is termed __________.
adaptation
What term refers to the presence of two or more variants for a given character in a population?
Multiple choice question.
Adaptation
Equilibrium
Polymorphism
Mutation
Polymorphism
If 99% or more of its alleles are identical, a gene is said to be ______; and it is ____________ if at least two alleles occur at a frequency greater than 1%.
monomorphic; polymorphic
The number of copies of an allele in a population divided by the total number of all alleles for that gene in a population is the ______.
Multiple choice question.
allele frequency
genotype frequency
frequency of heterozygosity
SNP frequency
allele frequency
The genotype frequency is calculated by dividing the number of individuals in a population who have a particular ______ by the total number of ______ in that population.
Multiple choice question.
genotype; individuals
genotype; genotypes
allele; genotypes
allele; alleles
genotype; individuals
If a population of mammals moves from a warm geographic location to a colder geographic location, individuals with a(n) ______ such as thicker fur might be more likely to survive and reproduce in the new environment due to ______.
Multiple choice question.
vestigial structure; natural selection
adaptation; natural selection
adaptation; artificial selection
vestigial structure; artificial selection
adaptation; natural selection
The frequency at which homozygotes and heterozygotes occur within a population can be described by ______.
Multiple choice question.
genotype frequencies
relative fitness of a genotype
allele frequencies
SNP frequency per gene
genotype frequencies
The reason why allele frequencies is not the right answer is because allele frequencies describe the frequencies of individual alleles (e.g., A or a). Genotype frequencies describe the frequencies with with combinations of alleles, or genotypes, occur (e.g., AA, Aa, or aa).
In four-o’clock plants, flowers with the genotype CRCR are red, flowers with the genotype CRCW are pink, and flowers with the genotype CWCW are white. A population of four-o’clocks consists of 30 plants with red flowers, 10 plants with pink flowers, and 60 plants with white flowers. What is the frequency of the CR allele in this population?
Multiple choice question.
- 65
- 20
- 70
- 35
0.35
Ooooo
For the first part of the equation, you need to count all instances of Cr… That means, 10 + 60 because CRCR has two of the alleles in question.
10 + 30 + 30 = 70
Divided by the total amount of alleles in the population
(30 x 2) + (10 x 2) + (60 x 2) = 200
70/200 = .35
In a diploid species, how many copies of a given allele are present in an individual who is heterozygous for the gene?
Multiple choice question.
2
0
4
1
1
Not two because a heterozygote has two copies of the genes, bot only one copy of each allele.
The allele frequency is calculated by dividing the number of copies of a specific ______ in a population by the ______ for that gene in that population.
Multiple choice question.
genotype; total number of individuals
allele; total number of individuals
allele; total number of all alleles
genotype; total number of all genotypes
allele; total number of all alleles
In radishes, genotype RR is red, genotype Rr is purple, and genotype rr is white. In a population of radishes consisting of 100 red radishes, 100 purple radishes, and 300 white radishes, what is the frequency of the genotype rr?
Multiple choice question.
- 33
- 25
- 70
- 60
0.60
The number of individuals with a particular genotype in a population divided by the total number of individuals in a population is the ______.
Multiple choice question.
polymorphism frequency
Hardy-Weinberg equilibrium
allele frequency
genotype frequency
genotype frequency
Consider a population of 100 four o’clock flowers. In this population, 55 flowers are red and have the genotype CRCR, 20 flowers are pink and have the genotype CRCW, and 25 flowers are white with the genotype CWCW. The frequency of the CR allele in this population is ________%.
65
Consider a population of flowers in which the genotype CRCR produces red flowers, CRCW produces pink flowers, and CWCW produces white flowers. If the frequency of the CR allele is 0.2 and the frequency of the CW allele is 0.8, what is the frequency of the red flower genotype?
- 40
- 20
- 32
- 04
.04
The frequency of the homozygous genotype, CRCR, when the frequency of allele is known; just square the allele frequency in question.
.2 x .2 or .2^2 = .04
A diploid homozygous individual has ______ copies of the given allele.
Multiple choice question.
0
4
2
1
2
A particular gene segregates two alleles, and the dominant allele has a frequency of 0.9. What is the frequency of the recessive allele?
Multiple choice question.
- 3
- 9
- 5
- 1
0.1
Remember: p + q = 1
This can be used if one allele frequency is known.
The Hardy-Weinberg equation states for a gene exists in two alleles and the genotypes can be found.
The MN blood group in humans is determined by two alleles of a single gene. In a population containing 90 individuals with genotype MM and blood group M, 80 individuals with genotype MN and blood group MN, and 30 individuals with genotype NN and blood group N, what is the frequency of the genotype MN?
Multiple choice question.
- 40
- 80
- 70
- 65
.40
90 = MM genotype
80 = MN genotype
30 = NN genotype
A student proposes that left-handedness is a recessive trait. A survey of a class of 36 students finds that 27 (0.75) are right-handed and 9 (0.25) are left-handed. If this population is in Hardy-Weinberg equilibrium, what are the genotypic and allele frequencies?
Multiple choice question.
- 75 homozygous dominant and 0.25 homozygous recessive, and a 3-to-1, right-to-left handed allele ratio in the population
- 25 homozygous dominant, 0.50 heterozygous, and 0.25 homozygous recessive, and a 0.5 allele frequency for each allele
- 50 homozygous dominant, 0.25 heterozygous, and 0.25 homozygous recessive, and a 0.5 allele frequency for each allele
They cannot be estimated using these limited data.
p^2 + 2pq + q^2 = 1
p + q = 1 (.75 + .25 = 1)
Reason: The frequency of left-handed individuals represents q2 in the Hardy-Weinberg equation. Taking the square root of 0.25 = 0.5 = q. Since p + q = 1, p = 0.5. Then use the equation to find the frequencies of the genotypes.
Correct Answer: 0.25 homozygous dominant, 0.50 heterozygous, and 0.25 homozygous recessive, and a 0.5 allele frequency for each allele
Consider a gene that segregates two alleles, A and a, with allele frequencies given by p and q, respectively. The frequency of the aa genotype will be ______ if the population is in Hardy-Weinberg equilibrium.
q2
2pq
p2
pq
q
q2
Reason: No. 2pq is the expected frequency of the Aa genotype.
Reason: No. p2 is the expected frequency of the AA genotype.
Reason: No. q is the frequency of the a allele. The aa genotype has two a alleles, so its frequency is q X q, or q2.
Suppose plants with the genotype FRFR produce red flowers, plants with the genotype FRFW produce pink flowers, and plants with the genotype FWFW produce white flowers. If the frequency of the FR allele is 0.2 and the frequency of the FW allele is 0.8, what is the frequency of pink flowers?
Multiple choice question.
- 50
- 32
- 04
- 16
0.32
