BIO150- Chapter 19

Consider a population with 100 cats. If 72 cats are black and 28 cats are white, what is the phenotypic frequency of black cats?

.72

Regarding a particular trait in a population of painted turtles, 14% of the turtles have the homozygous dominant genotype, 70% are heterozygous, and 16% are homozygous recessive. What is the value of q^2?

0.16

In a population with three genotypes for a particular gene, what is the sum of all the genotype frequencies equal to?

1

If the probability of an individual being Bb is pq and the probability of an individual being bB is qp, what is the total probability that the individual will be heterozygous in this population?

2pq

A characteristic that confers a survival advantage is.. A) likely to also increase reproductive success and, as a consequence, favored by natural selection B) not likely to increase reproductive success and should not be favored by natural selection

A

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? A) genetic variation B) equilibrium C) heterozygosity D) population genetics

A) genetic variation

Select all of the following that increase the chances of genetic drift in a population A) a few individuals of a population become isolated B) only a few individuals contribute gametes to the next generation C) migration into a population occurs D) a population becomes very small E) natural selection is acting upon the population

A, B, and D

Select all of the following that are examples of gene flow A) drifting of gametes of marine animals B) self-pollination among flowering plants C) seeds being blown by the wind far from their origin D) the carrying of pollen by insects over great distances E) migration of animals from one place to another

A, C, D, E

Select all of the following criteria that must be present for natural selection to occur and cause evolutionary change in a population A) Variation must have a genetic basis B) Variation must be the result of environmental differences C) Variation must result in differences in the number of offspring surviving in the next generation D) Variation must exist among individuals

A, C, and D

Select all of the following factors that limit what selection can accomplish A) interactions between genes B) equal allele frequencies C) lack of genetic variation D) pleitropy

A, C, and D

Select which of the following are reasons why a population bottlemeck can lead to genetic drift. A) the gene pool of the surviving members of the population may be different from the original gene pool B) the magnitude of genetic drive increases as population size increases C) very few individuals contribute to the next generation D) small populations are more sensitive to genetic drift

A, C, and D

Select all of the following that could cause a population to deviate from the hardy-weinberg equilibrium A) random mating between individuals of the population B) emigration from the population C) immigration of homozygotes D) natural selection favoring heterozygotes E) reduction to a small population size F) Lack of mutation

B through E

Gene loci have exhibit more than one allele at frequencies greater than would occur due to a mutation are called which of the following? A) Wobbled B) Allelic C) Polymorphic D) Neutral

C) Polymorphic

True or false: If the frequency of allele t in a population is 0.3 and the frequency of the genotype tt in the population is .20, then the population is in Hardy-Weinberg equilibrium

False

True or false: When a population is in Hardy-Weinberg equilibrium, natural selection is occurring.

False

In what type of selection is a phenotype favored based on how common or uncommon it is?

Frequency-dependent selection

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

Gene flow

What are the five agents that can act to produce evolutionary changes in a population?

Genetic drift in small populations, mutations, nonrandom mating, gene flow, and natural selection

What changes in genetic variation in a population are expected after a population bottleneck followed by population growth and a return to the original population size?

Genetic variation will be decreased

After Mendel's work was rediscovered, what scientists explained why a population doesn't always come back to be composed solely of individuals with the dominant phenotype?

Hardy and Weinberg

If population 1 is in Hardy-Weinberg equilibrium such that p = 0.7 and q = 0.3, select all of the following that would result if mating began to occur with the adjacent population 2 in which p = 0.1 and q = 0.9

In population 2, p will increase In population 1, q will increase Population 1 will shift out of Hardy-Weinberg equilibrium

How does genetic drift affect allele frequencies?

It changes allele frequencies randomly

Consider a gene with two alleles, one dominant, and the other recessive. If this population is in Hardy-Weinberg equilibrium with respect to this gene, what would happen to the dominant allele from generation to generation?

Its frequency will remain unchanged.

What is the ultimate source of all new alleles?

Mutation

What evolutionary process is occurring if individuals with certain genotypes mate with each other more commonly than would be expected on a random basis?

Nonrandom mating

What hypothesis would you investigate if you observed a population that had a higher frequency of homozygotes than the predicted Hardy-Weinberg equation?

Nonrandom mating was occurring

why was genetic variation within natural populations a puzzle to darwin and other scientists in the 19th century?

Segregation of alleles among progeny of hybrids was not understood, genetic variants were expected to be diluted to the point of disappearing in future generations, and scientists thought that selection should always favor optimal form

How can the founder effect cause a previously rare genetic disorder to become common in the new population?

The allele frequencies in the founding members of the population differ from the allele frequencies in the original large population

What is population genetics?

The study of the properties of genes in populations

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 _____

allele frequency

The bottleneck effect occurs when allele frequencies change due to..

an even that drastically reduces population size

frequency-dependent selection favors phenotypes which...

are rare or common

Why does selection occur?

because some individuals in a population possess more favorable phenotypes than others

what is the founder effect?

changes in allele frequencies that result from the colonization of a new location by a small group of individuals from a larger population

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

directional selection

Darwin, along with many earlier naturalists, proposed that diversity among living things was produced by the process of ____

evolution

The accumulation of differences in species that causes new species to arise from existing ones is a process called...

evolution

True or false: Darwin was the first to propose that diversity of life arose from the evolution of species

false

The Hardy-Weinberg equation assumes that...

gametes combine randomly

What evolutionary process is occurring when individuals belong to adjacent populations mate with each other?

gene flow

Multiple ____ genes are usually responsible for most traits

genes

Evolution can result from any process that changes the ______ composition of a population

genetic

What evolutionary mechanism results in random changes in allele frequencies from one generation to the next?

genetic drift

A key assumption of evolution by natural selection is that populations contain ______, which can be described as alternative alleles for a trait

genetic variation

Assortative mating changes ___ frequences but does not change ______ frequences.

genotype; allele

A situation where individuals with two different alleles at a gene locus are favored over individuals with two of the same alleles at the locus is called ____ advantage

heterozygous

which theory proposes that variation among individuals is created by experience, not by pre-existing genetic differences?

inheritance of acquired characteristics

The scientist Jean-Baptiste Lamarck, proposed that changes aquired by individuals during their lifetimes were passed on to offspring, a theory called __________ of acquired __________

inheritance; characteristics

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

When the heterozygous advantage exists, how would you describe the fitness of the heterozygous genotype?

it has higher fitness than either homozygote

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

it maintains genetic variation in a population

If blending inheritance occurred when mixing a purple-flowered plant with a white-flowered plant, what color flowers would be produced?

light purple

Darwin referred to evolution as "descent with ___"

modification

Darwin proposed that the mechanism of evolution is

natural selection

In a population that is in Hardy-Weinberg equilibrium, proportions of genotypes are...

not changing

In the Hardy-Weinberg equation, the allele frequencies of a gene can be represented by...

p and q

For a gene with two alleles, B and b whose frequencies are p and q respectively, the probability that an individual receives a B allele from its mother and a B allele from its father is....?

p^2

What is the correct version of the Hardy-Weinberg equation for genotype frequencies in a population equilibrium?

p^2 + 2pq + q^2 = 1

Selection occurs because some individuals in a population have more favorable ______ than others in the same population and leave more progency than others

phenotypes

A gene locus that has more than one allele at a frequency significantly greater than would be predicted due to mutation alone is called a ____ gene locus

polymorphic

If a gene has two alleles, R and r, the frequency of the R allele can be designated as p and the frequency of the r allele can be designated as...

q

the amount of genetic variation present in naturally occurring populations is..

significant

The changes in allele frequencies that occur due to the colonization of a new location by a small group of individuals is called..

the founder effect

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

the rate at which mutations occur is low

what is fitness?

the relative likelihood that a phenotype will produce the most offspring

True or false: The Hardy-weinberg equation assumes that gametes combine with one another randomly with respect to their genotypes

true