CH 23 MASTERING BIO

Arrange the following in order from most general to most specific. 1 natural selection 2. microevolution 3. intrasexual selection 4. evolution 5. sexual selection 4, 2, 1, 3, 5 1, 4, 2, 5, 3 4, 2, 1, 5, 3 4, 1, 2, 3, 5

4, 2, 1, 5, 3

Which statement about variation is true? All nucleotide variability results in neutral variation. All phenotypic variation is the result of genotypic variation. All genetic variation produces phenotypic variation. All new alleles are the result of nucleotide variability.

All new alleles are the result of nucleotide variability.

Different finch species have beaks of different shapes and sizes. What do these beak differences tell us? Different finch beak shapes are evidence that all Galápagos finches share a common ancestor. Different finch beak shapes are evidence that individual birds changed their beaks so that they could feed efficiently. Different finch beak shapes are evidence that finch species adapted to different environments over many generations. Different finch beak shapes are evidence that several finch species with different beak types came to the Galápagos Islands from the mainland.

Different finch beak shapes are evidence that finch species adapted to different environments over many generations.

Which statement about the beak size of finches on the island of Daphne Major during prolonged drought is true? Each bird that survived the drought produced only offspring with deeper, stronger beaks than seen in the previous generation. The frequency of the strong-beak alleles increased in each bird as the drought persisted. Each bird's survival was strongly influenced by the depth and strength of its beak as the drought persisted. Each bird evolved a deeper, stronger beak as the drought persisted.

Each bird's survival was strongly influenced by the depth and strength of its beak as the drought persisted.

Which of the following are basic components of the Hardy-Weinberg model? Allele frequencies, number of individuals in the population Frequencies of two alleles in a gene pool before and after many random matings Allele frequencies in a subset of the population Allele frequencies, phenotype frequencies

Frequencies of two alleles in a gene pool before and after many random matings

One of the following is NOT a source of genetic variation. genetic drift alteration of gene number or position sexual reproduction mutation rapid reproduction

Genetic Drift

How does diploidy help to preserve genetic variation? See Concept 23.4 (Page 498) View Available Hint(s) It helps individual organisms make a greater contribution to the gene pool of the next generation. It fosters the exchange of genes between different populations. It allows recessive alleles that may not be favored in the current environment to be preserved in the gene pool by propagation in heterozygotes. It allows the frequency of a recessive allele in a population to be predicted under certain conditions. It restricts the gene pool by chance events such as floods or other catastrophic events.

It allows recessive alleles that may not be favored in the current environment to be preserved in the gene pool by propagation in heterozygotes.

What is true of microevolution? See Concept 23.1

It is the kind of evolution that can change the relative abundance of a particular allele in a gene pool over the course of generations.

Genetic evidence supports which of the following explanations for the presence of 13 different finch species on the Galápagos islands? Each of the 13 species migrated to the islands at different times over the years. Many years ago, more than 13 different species of birds migrated to the islands. The current 13 finch species are the only species that survived. The 13 species have existed on the Galápagos islands since the islands first formed. Many years ago, a small population of a single finch species migrated to the islands and evolved into the current 13 species.

Many years ago, a small population of a single finch species migrated to the islands and evolved into the current 13 species.

In 1986, a nuclear power accident in Chernobyl, USSR (now Ukraine), led to high radiation levels for miles surrounding the plant. The high levels of radiation caused elevated mutation rates in the surviving organisms, and evolutionary biologists have been studying rodent populations in the Chernobyl area ever since. Based on your understanding of evolutionary mechanisms, which of the following most likely occurred in the rodent populations following the accident? Mutations caused major changes in rodent physiology over time. Mutation caused genetic drift and decreased fitness. Mutation caused the fixation of new alleles. Mutation led to increased genetic variation.

Mutation led to increased genetic variation.

Part complete The fruit fly Drosophila melanogaster has an allele that confers resistance to DDT and similar insecticides. Laboratory strains of D. melanogaster have been established from flies collected in the wild in the 1930s (before the widespread use of insecticides) and the 1960s (after 20 years of DDT use). Lab strains established in the 1930s have no alleles for DDT resistance. In lab strains established in the 1960s, the frequency of the DDT-resistance allele is 37%. Which statement is correct? The evolutionary fitness associated with the heritable trait of DDT resistance changed once DDT use became widespread. Resistance to DDT evolved in some fruit flies in order to allow them to survive. Alleles for DDT resistance arose by mutation during the period of DDT use because of selection for pesticide resistance.

The evolutionary fitness associated with the heritable trait of DDT resistance changed once DDT use became widespread.

Which of the following statements is not a part of the Hardy-Weinberg principle? If allele frequencies in a population are given by p and q, then genotype frequencies will be given by p 2, 2pq, and q 2 for generation after generation. The genotype frequencies in the offspring generation must add up to two. When alleles are transmitted according to the rules of Mendelian inheritance, their frequencies do not change over time. Even if allele A1 is dominant to allele A2 , it does not increase in frequency.

The genotype frequencies in the offspring generation must add up to two.

Which statement correctly describes the role of chance in evolution? An allele that increases evolutionary fitness cannot be lost from a population by chance events. Evolution by natural selection proceeds by an accumulation of changes that occur by chance. The ultimate source of new alleles is mutation, random changes in the nucleotide sequences of an organism's DNA

The ultimate source of new alleles is mutation, random changes in the nucleotide sequences of an organism's DNA

Microevolutions occur when ________. gene flow evenly transfers alleles between populations changes in allele frequencies in a population occur over generations individuals within all species vary in their phenotypic traits a bird has a beak of a particular size that does not grow larger during a drought

changes in allele frequencies in a population occur over generations

Use the following information to answer the question below. In those parts of equatorial Africa where the malaria parasite is most common, the sickle-cell allele constitutes 20% of the β hemoglobin alleles in the human gene pool. In the United States, the parasite that causes malaria is not present, but it is present in African-Americans whose ancestors were from equatorial Africa. What should be happening to the sickle-cell allele in the United States, and what should be happening to it in equatorial Africa? stabilizing selection; disruptive selection disruptive selection; stabilizing selection directional selection; disruptive selection directional selection; stabilizing selection

directional selection; stabilizing selection

What situation most likely explains the occasional high frequency of certain inherited disorders among human populations established by a small population? gene flow mutation nucleotide variability founder effect bottleneck effect

founder effect

Part complete 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 likely explains the genetic uniqueness of this population? mutation and natural selection heterozygote advantage and stabilizing selection founder effect and genetic drift population bottleneck and Hardy-Weinberg equilibrium

founder effect and genetic drift

Allele frequencies in a gene pool may shift randomly and by chance. What is this random shift called? genetic drift gene flow directional selection

genetic drift

Which Hardy-Weinberg condition is affected by population size? no mutation genetic drift gene flow selection

genetic drift

In the formula for determining a population's genotype frequencies, the "2" in the term 2pq is necessary because _____. heterozygotes have two alleles the population is diploid heterozygotes can come about in two ways the population is doubling in number

heterozygotes can come about in two ways

In the formula for determining a populations genotype frequencies, the "pq" in the term 2pq is necessary because _____. the population is doubling in number heterozygotes can come about in two ways the population is diploid heterozygotes have two alleles

heterozygotes have two alleles

Genetic variation ________. tends to be reduced when diploid organisms produce gametes is created by the direct action of natural selection must be present in a population before natural selection can act upon the population arises in response to changes in the environment

must be present in a population before natural selection can act upon the population

The original source of all genetic variation is _____ mutation recombination natural selection sexual reproduction independent assortment

mutation

Which of the following evolutionary forces could create new genetic information in a population? View Available Hint(s) Mutation Nonrandom mating Selection Genetic drift

mutation

What is the only evolutionary mechanism that consistently leads to adaptive evolution? the bottleneck effect neutral variation natural selection genetic drift gene flow Submit

natural selection

Part complete If individuals tend to mate within a subset of the population, there is ________. no genetic drift no gene flow no selection no random mating

no random mating

The higher the proportion of loci that are "fixed" in a population, the lower are that population's ________. nucleotide variability and average heterozygosity average heterozygosity nucleotide variability chromosome number

nucleotide variability and average heterozygosity

Which of the following evolutionary forces consistently results in adaptive changes in allele frequencies? View Available Hint(s) Selection Inbreeding Mutation There is no evolutionary force that results in adaptive changes in allele frequencies.

selection

According to the Hardy-Weinberg theorem, the frequencies of alleles in a population will remain constant if _____ is the only process that affects the gene pool. immigration genetic drift mutation sexual reproduction sexual selection

sexual reproduction

Which one of the following conditions would allow gene frequencies to change by chance? large population small populations gene flow mutation

small pop.

True or false? The Hardy-Weinberg model makes the following assumptions: no selection at the gene in question; no genetic drift; no gene flow; no mutation; random mating. True False

true