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