Bio 11a ch 20.1, 20.4 20.6-20.8

Let's say you inoculate four agar plates, each containing a different antibiotic (A, B, C, and D), and you add a swab from a lesion taken from a patient. After incubating the plates, you observe that plate A has only a few colonies, while the others all have many colonies. How do you interpret the results?

Bacteria in the patient's sample are susceptible to antibiotic A but not B, C, and D

The source of all genetic variation is mutation, a random change in the nucleotide sequence of an organism's

DNA

Many 19th century scientists believed that natural selection always favored an optimal form, and therefore would tend to reduce or eliminate which of the following?

Genetic variation

Which of the following best describes the mechanism of action of the antibiotic streptomycin?

It disrupts protein synthesis in nonresistant bacteria.

By favoring different phenotypes at different times, oscillating selection acts in which way?

It maintains genetic variation in a population.

Evolutionary change within a population can result from which of the following?

Mutations Migration Natural selection

phenotype

characteristic of an organism that can be observed and measured

inoculate

introducing microorganisms into a culture medim.

Which of the following is the source of new, novel alleles in a population?

mutation

Mutation

random change in the DNA sequence of an organism

gene pool

the complete set of genes in a given population of organisms

New mutations are not a major factor affecting the allele frequencies in a population because

the rate at which new mutations occur is low

For a population to be in Hardy-Weinberg equilibrium,

there must be no migration into or out of the population.

In a sample population of people, 36% have the recessive trait of "free" earlobes (q2). What is the frequency of the dominant allele for attached earlobes, p?

.40

In a population, 25% of individuals exhibit albinism which is a lack of production of the pigment melanin. It is caused by two recessive allele (q2). What is the frequency of the recessive allele (g) in this population?

.50

In a population of seahorses, red seahorses on average produce 125 offspring and brown seahorses produce 75 offspring. What is the fitness of the brown phenotype?

0.6

The most fit phenotype is assigned a fitness value of ______.

1

In a species of rodent, white coat color is recessive to the dominant brown color. In a population of 100 individuals, 16 are white and 84 are brown. Of the 84 brown ones, how many are expected to be heterozygous (2pq)?

48

Which evolutionary mechanism changes genotype frequencies but does not change allele frequencies?

Assortative mating

How does an antibiotic act as a selective agent in promoting bacterial resistance?

Bacteria with a random mutation that allows resistance to that antibiotic are able to survive exposure and reproduce, passing the resistance mutation on to subsequent generations of bacteria.

Why does selection occur?

Because some individuals in a population possess more favorable phenotypes than others.

Which type of selection favors individuals at one extreme of a phenotypic range who have greater reproductive success in a particular environment?

Directional selection

Selection against intermediate-sized beaks in African black-bellied seedcracker finches is an example of which of the following?

Disruptive selection

Which type of selection acts to eliminate individuals which are intermediate on a phenotypic range?

Disruptive selection

What conclusion can be drawn from the observation that a population is not in Hardy-Weinberg equilibrium?

Evolutionary forces are affecting the population.

Which of the following is true of evolutionary forces in natural populations?

Evolutionary forces can alter allele frequencies in natural populations

Which of the following agents of evolutionary change occurs when alleles move from one population to another?

Gene flow

Even though a population in true Hardy-Weinberg equilibrium cannot exist, how can using the equation be useful?

It can be used to detect changes in gene frequencies in a population over time.

How does genetic drift affect allele frequencies?

It changes allele frequencies randomly

all of the following processes that can cause changes in allele or genotype frequencies in populations.

Mutations Natural selection Genetic drift Gene flow Nonrandom Mating

For natural selection to occur, there must be some preexisting genetic variation in a population

Natural selection does not create the variation. Instead, it impacts individuals differently based on their genotype.

If we find evidence that a population is experiencing changes in allele frequencies from one generation to the next, we say that this population is which of the following?

Not in Hardy-Weinberg equilibrium

In Northeastern South America, which of the following is the main predator in streams found just below waterfalls?

Pike cichlids

What type of selection affects traits that influence an individual's chances to find a mating partner or be chosen as a mating partner?

Sexual selection

Genetic drift has a greater impact on which of the following?

Small populations

Which type of selection favors individuals with intermediate phenotypes and selects against individuals with extreme phenotypes?

Stabilizing selection

an antibiotic that can be used to kill bacteria by inhibiting protein synthesis, but bacteria can develop resistance to streptomycin.

Streptomycin

Which of the following apply to the development of streptomycin resistance in E. coli?

The E. coli population has genetic variation. The selective agent is streptomycin. The mutation resulting in streptomycin resistance is random.

If 10 Typica moth and 90 Carbonaria moth were released into a polluted forest what would happen over several generations?

The Typica moth population would decline. The Carbonaria moth population would have a reproductive advantage in the polluted forest. The recessive allele frequency would decrease each generation.

The most fit phenotype produces, on average, which of the following?

The greatest number of surviving offspring

What is gene flow?

The movement of alleles into or out of a population.

Select the conditions that must be met for a population to be in Hardy-Weinberg equilibrium.

The population is very large. Mating is random. No new mutations occur.

What is fitness?

The relative likelihood that a genotype will contribute to the gene pool of the next generation

What does it mean for a population to be in Hardy-Weinberg equilibrium?

There are no changes in gene frequencies from one generation to the next.

Which describes male guppies located below South American waterfalls where predation is high?

They exhibit drab coloration.

In a laboratory experiment, researchers placed guppies in three different types of pools: no predation, low predation, and high predation. Researchers hypothesized that predation is a selective force and that large, brightly colored guppies are more conspicuous to predators. Based on that, what would you predict the guppies will look like in the pool with high predation after 10 generations?

They should be smaller and not very brightly colored

What is the purpose of the sterile spreader?

To uniformly disperse bacterial cells across the surface of the agar plate. Spreading the bacteria out will allow individual colonies to form.

Natural selection has 3 requirements:

Variation must exist in the population. The variation must be transmissible to the next generation. The variation must lead to differences in reproductive success.

Select all of the following criteria that must be present for natural selection to occur and cause evolutionary change in a population.

Variation must have a genetic basis. Variation must exist among individuals. Variation must result in differences in the number of offspring surviving in the next generation.

Natural selection occurs when

a new genetic variation occurs that allows individuals to have a reproductive and survival advantage.

agar plate

a plastic petri plate filled with a thick gelatinous media used to culture/grow bacteria

colony

a single original bacterial cell dividing to become a visible collection of identical bacteria

reproductive success

ability of an individual in a population to survive, reproduce and pass on genetic traits to the next genetic traits to the next generation

The term heterozygote ________refers to situations in which heterozygotes are more fit then either homozygotes.

advantage

Genetic variation in a population results from evolutionary forces that cause changes in

allele frequencies

on which of these plates should we expect to see colonies of e coli growing after incubation

antibiotic-resistance e coli on streptomycin-negative plate antibiotic-resistant E.coli on streptomycin-positive plate antibiotic nonresistance e coli on streptomycin negative plate

Incubate

bacteria typically grown in ideal conditions for a period of time to allow reproduction and colony formation

When researchers raised guppies in laboratory pools with high levels of predation, the guppies in those aquariums

became smaller and drab in coloration as a result of natural selection after about 10 generations.

Suppose that a population of finches migrates to a small island where most of the seeds are large. On the island, birds with large beaks are more likely to survive, and over time, the mean beak size of the population increases. This is an example of a type of natural selection known as _________selection.

directional

Natural selection

drives evolution when certain environmental factors cause differences in the reproductive success of individuals with particular genotypes.

population in ______is not evolving; the allele ratios stay the same.

equilibrium

the change of heritable characteristics in a species over multiple generations through the process of natural selection.

evolution

In natural populations, most genes

exhibit variation.

What term quantifies reproductive success of a phenotype?

fitness

Sexual selection influences

fitness. mating success. mate choice.

In _________- __________selection, the fitness of a phenotype depends on the proportion of individuals in the population that have that phenotype.

frequency - dependent

Mutations happen during normal DNA replication or through unrepaired damage to DNA

from physical or chemical causes.

Natural populations exhibit significant phenotypic and_____ variation.

genetics or genotypic

Assortative mating changes ______ frequencies but does not change ______ frequencies.

genotype; allele

Consider a gene with two alleles, A1 and A2. If the fitness of A1A2 individuals is higher than the fitness of both A1A1 and A2A2, we are observing

heterozygote advantage.

According to the theory of blending Inheritance, offspring were expected to be phenotypically _______relative to their parents, which would dilute any new genetic variants.

intermediate

Hardy-Weinberg equilibrium requires that the population size is ______and that mating is________

large random

What is the ultimate source of all new alleles?

mutation

Changes in allele frequencies within a population may result from________ , which are changes in the nucleotide sequences of an organism's DNA.

mutations

Which of the following mechanisms of change in gene frequencies is responsible for the antibiotic resistance of E. coli in this experiment?

natural selection

When a population is in Hardy-Weinberg equilibrium

no natural selection is occurring.

Ground finches with large bills are favored during times of drought, while ground finches with small bills are favored during times when water is abundant. This is an example of

oscillating selection

hardy-Weinberg law

population allele and genotype frequencies do not change over time unless acted upon by evolutionary agents

Mutations leading to antibiotic resistance are

random events that lead to genetic variation.

Though useful mutations are rare events, given the large numbers of bacteria, a few will have developed

resistance mechanisms

Natural selection in bacteria occurs when a genetic mutation provides a reproductive advantage over organisms

that do not have the mutation.

reproductive success

the ability of an individual in a population to survive, reproduce and pass genetic traits to the next generation

Two agar plates, one containing the antibiotic streptomycin and one without antibiotics, are inoculated with E. coli. After incubation, the streptomycin negative plate has many bacterial colonies, while the streptomycin positive plate has only a few colonies. Samples of the colonies from the positive plate are placed on another positive plate, and after incubation many colonies grow. In this experiment, what is the selective agent?

the antibiotic streptomycin

Evolution

the change of heritable characteristics in a species over multiple generations through the process of natural selection.

genetic varation

the differences in DNA sequences between individuals

In frequency-dependent selection

the fitness of a phenotype depends on its frequency in the population.

genotype

the genetic makeup of an organism

natural selection

the mechanism that brings about adaptation of organisms to the environment as evolution occurs

population

the members of a species that live in a defined geographical area that can breed with each other

True or false: Genetic drift, mutations, and nonrandom mating are three agents that can act to produce evolutionary changes in a population.

true

allele

variation of genes often inherited in pairs

could overuse of unnecessary antibiotics result in a population of antibiotic resistant bacteria?

yes, because the antibiotic would select for any bacteria resistant to the antibiotic allowing only them to survive