Mastering Biology (The Evolution of Populations)

In a population that is in Hardy-Weinberg equilibrium, 64% of the individuals express the recessive phenotype for a particular gene locus. What is the expected frequency of the dominant allele in this population? A) 0.64 B) 0.2 C) 1 D) 0.04 E) 0.8

0.2

In a population that is in the Hardy-Weinberg equilibrium, 64% of the individuals express the recessive phenotype for a particular gene locus. What is the expected frequency of the recessive allele in this population? A) 1 B) 0.36 C) 0.64 D) 0.2 E) 0.8

0.8

In a certain group of people, 4% are born with sickle-cell disease (homozygous recessive). If this group is in Hardy-Weinberg equilibrium, what percentage of the group is heterozygous for the sickle hemoglobin allele? A) 4% B) 2% C) 16% D) 32% E) 8%

32%

Natural selection leads to adaptation, but there are many organisms on Earth that exhibit characteristics that are less than ideal for their environment. Which of the following statements correctly explain(s) this? A) selection can act only on existing variations B) evolution is limited by historical constraints C) all of the listed responses are correct D) adaptations are often compromises E) chance, natural selection, and the environment interact

All of the listed responses are correct.

Which of the following statements correctly describe(s) characteristics of genetic drift? A) all of the listed responses are correct B) it can lead to a loss of genetic variation in a population C) it can cause harmful alleles to become fixed in a population D) it can cause allele frequencies to change at random E) it is significant in small populations

All of the listed responses are correct.

Which of the following statements correctly describes a population in Hardy-Weinberg equilibrium? A) the population is evolving B) allele and genotype frequencies in the population change from generation to generation C) the population exhibits no genetic variation D) allele and genotype frequencies in the population will remain constant from generation to generation E) all of the listed responses are correct

Allele and genotype frequencies in the population will remain constant from generation to generation.

In the context of populations, how do we define evolution? A) evolution is the way in which sexual reproduction can rapidly spread advantageous traits throughout a population B) evolution is a change in a population's allele frequencies over generations C) evolution is always caused by natural selection D) evolution is the tendency for some individuals in a population to leave more offspring than others E) Evolution is the explanation for how organic molecules formed from inorganic molecules

Evolution is a change in a population's allele frequencies over generations.

Stabilizing selection __________. A) usually results in two distinct phenotypes B) occurs only in plants C) favors intermediate variants in a population D) occurs when some individuals migrate to an area with different environmental conditions E) prevent mutations from occurring

Favors intermediate variants in a population

Which of the following statements explains why male peacocks with brightly colored feathers are more prevalent than those with plain colors? A) female peacocks choose the plain-colored males as mates, causing this trait to be more prevalent in the population B) female peacocks choose the showiest males as mates, causing this trait to be more prevalent in the population C) female mate choice is random, and the showier males happen to be chosen by the females as mates D) showy males are larger and kill off the plain-colored males E) male peacocks with showy feathers have no selective advantage over plain-colored males

Female peacocks choose the showiest males as mates, causing this trait to be more prevalent in the population.

Which of the following would seem to be an example fo neutral variation? A) moth coloration B) polymorphism of the Galapagos finches C) human fingerprints D) homozygosity of the cheetah population E) founder effect

Human fingerprints

Which of the following can form entirely new alleles? A) mutation B) natural selection C) genetic drift D) sexual recombination E) the environment

Mutation

All of the following conditions are required for Hardy-Weinberg equilibrium except _______________. A) natural selection B) random mating C) no mutation D) a large population E) no gene flow

Natural selection

Which of the following sets of conditions is required for Hardy-Weinberg equilibrium? A) no mutations, no natural selection, with sexual selection B) random mating, no natural selection, and a large population C) a large population, no mutations, with natural selection D) random mating, a small population, and no mutations E) a large population, random mutations, and no migration of alleles in or out of the population

Random mating, no natural selection, and a large population

Which statement below is true about sexual selection? A) intrasexual selection leads to the deaths of the most unfit males in combat B) Sexual selection can result in sexual dimorphism—marked differences between the sexes in secondary sexual characteristics that are not associated directly with reproduction. C) there is no evidence that intrasexual selection takes place between females D) in most vertebrates, females court the males E) showy secondary sexual characteristics cannot be explained because they break all of the rules of natural selection

Sexual selection can result in sexual dimorphism—marked differences between the sexes in secondary sexual characteristics that are not associated directly with reproduction.

A hurricane hits a small island, killing all but a few members of a bird population. This is an example of __________. A) the bottleneck effect B) the founder effect C) random mating D) gene flow E) natural selection

The bottleneck effect

In the Hardy-Weinberg equation, 2pq represents ______________. A) the expected frequency of the homozygous recessive genotype B) the expected frequency of the heterozygous genotype C) the expected frequency of the dominant allele D) the expected frequency of the recessive allele E) the expected frequency of the homozygous dominant genotype

The expected frequency of the heterozygous genotype

In the Hardy-Weinberg equation, q^2 represents _____________________. A) the expected frequency of the homozygous recessive genotype B) the expected frequency of the dominant allele C) the expected frequency of the heterozygous genotype D) the expected frequency fo the homozygous dominant genotype E) the expected frequency of the recessive allele

The expected frequency of the homozygous recessive genotype

A storm separates a small number of birds in a migrating population. These birds end up at a destination different from where they usually migrate and establish a new population in this new area. This is an example of __________. A) the bottleneck effect B) gene flow C) mutation D) the founder effect E) natural selection

The founder effect

At what level does gene variability quantify genetic variation? A) species B) population C) individual D) whole-gene E) molecular

Whole-gene

Which of the following is the best example of gene flow? A) wind blows pollen from one population of plants to another and cross-fertilization occurs B) an earthquake results in the formation of a canyon, splitting a population of toads apart C) genes are shuffled by the crossing over of chromosomes during meiosis D) a fire drastically reduces the size of a white-tailed deer population. The remaining individuals spread out throughout the remaining forest E) a small population of humans colonizers a newly formed island

Wind blows pollen from one population of plants to another and cross-fertilization occurs.

The gene pool of a population consists of _______________. A) only the gene loci that are heterozygous B) all of the genes in a single organism C) all copies of every type of allele at every locus in all members of the population D) only the gene loci that exhibit variation within the population E) all of the genes in the females of a population F) only the gene loci that are homozygous

all copies of every type of allele at every locus in all members of the population

Which type of selection maintains stable frequencies of two or more phenotypic forms in a population? A) neutral variation B) balancing selection C) directional selection D) stabilizing selection E) heterozygote advantage

balancing selection

Antibiotic resistance in bacteria is an example of which of the following? A) disruptive selection B) macroevolution C) stabilizing selection D) directional selection E) Hardy-Weinberg equilibrium

directional selection

A population of squirrels is preyed on by small hawks. The smaller squirrels can escape into burrows. The larger squirrels can fight off the hawks. After several generations, the squirrels in the area tend to be very small or very large. What process is responsible for this outcome? A) disruptive selection B) Hardy-Weinberg equilibrium C) stabilizing selection D) balancing selection E) directional selection

disruptive selection

Which type of mutation plays the most important role in increasing the number of genes in the gene pool? A) point mutation B) mutations are so rare that there are no mutations that an have such an important effect C) duplication D) rearrangement of gene loci E) changes in nucleotide sequence

duplication

Sexual recombination includes the shuffling of chromosomes in __________ and fertilization. A) genetic drift B) meiosis C) mutation D) natural selection E) mitosis

meiosis

Point mutations in noncoding regions of DNA result in ____________. A) population variation B) protein variability C) none of the listed responses is correct D) neutral variation E) phenotypic variation F) gene variability

neutral variation

No two people are genetically identical, except for identical twins. The main source of genetic variation among human individuals is ______________. A) new mutations that occurred in the preceding generation B) geographic variation within the population C) environmental effects D) the reshuffling of alleles in sexual reproduction E) genetic drift due to the small size of the population

the reshuffling of alleles in sexual reproduction