Deck 16: How Populations Evolve

Question 1

Which of the following is/are a biological "population?"

A) all of the corn plants in a cornfield
B) all of the variable-colored ladybird beetles of the species Harmonia axyridis in a forest
C) all male and female English sparrows that reside in your community
D) all of the human population of a rural western town
E) All of the choices are correct.

Answer 1

E

Question 2

Which statement is NOT true about the Founder Effect?

A) It is a form of genetic drift.
B) It produces a high frequency of some rare alleles in a small isolated population.
C) Founding members contain a tiny fraction of the alleles found in the original population.
D) The Founder Effect occurs when a population is subjected to near extinction and then recovers so that only a few alleles are left in survivors.

Answer 2

D

Question 3

A random alteration in the sequence of DNA nucleotides that provides a new variant allele is

A) gene mutation.
B) polymorphism.
C) gene frequency.
D) disruption.

Answer 3

A

Question 4

All the members of a single species that occupy a particular area at the same time are known as a

A) subspecies.
B) gene pool.
C) population.
D) group.
E) sub-population.

Question 5

Which of the following would change the allele frequencies of a population?

A) DNA is stable from generation to generation and does not change, so allele frequencies do not change.
B) Tall people in a population preferentially marry other tall people and do not marry people who are short or average height.
C) A population on an island remains isolated and no one leaves or moves onto the island.
D) All of the answer choices would change allele frequencies of a population.

Question 6

A student proposes that left-handedness is a recessive trait that is therefore hidden in much of the human population. A survey of a class of 36 students finds that 27 (0.75) are right-handed and 9 (0.25) are left-handed. Using the Hardy-Weinberg formula, what would the expected genotypes and allele frequencies be in this theoretical population?

A) 0.75 homozygous dominant and 0.25 homozygous recessive, and a 3-to-1, right-to-left handed allele ratio in the population.
B) 0.25 homozygous dominant, 0.50 heterozygous, and 0.25 homozygous recessive, and a 0.75 dominant allele frequency and a 0.25 recessive allele frequency.
C) 0.25 homozygous dominant, 0.50 heterozygous, and 0.25 homozygous recessive, and a 0.5 allele frequency for each allele.
D) 0.50 homozygous dominant, 0.25 heterozygous, and 0.25 homozygous recessive, and a 0.5 allele frequency for each allele.
E) They cannot be estimated using these limited data.

Question 7

Variations within a population are maintained by

A) mutation.
B) genetic recombination due to fertilization.
C) gene flow.
D) All of the choices are correct.

Question 8

The recessive allele for sickle cell anemia is more prevalent in regions of Africa where malaria is prevalent, than it is in regions where there is no malaria. This is due to a

A) heterozygous advantage.
B) Founder Effect.
C) frequency dependent selection.
D) bottleneck effect.

Question 9

What is the term used to describe the changes in allele frequencies of a population over generations?

A) genetic drift
B) founder effect
C) microevolution
D) directional selection

Question 10

Which of the following is true about genetic drift?

A) It is more likely to occur in a large population than in a small population.
B) It may lead to an allele's becoming fixed in a population when its alternative allele is lost from the population.
C) It increases the number of heterozygotes in a population.
D) It increases the frequency of rare alleles in a population.

Question 11

Our domesticated honey bee-originally from Europe-is slow to sting, requires abundant flower nectar, gets up late in the morning, and stores much honey but only produces enough new brood to swarm once a year. Because the European honey bee was performing poorly as a honey producer in South America, the African subspecies was imported in a breeding experiment. The African honey bee formed small nests, foraged earlier and on smaller nectar sources, produced less honey stores and more brood, swarmed four or five times a year, and was fast to sting. However, when the African queens escaped, the two populations interbred and the African genotype spread several hundred miles north each year. Surprisingly, a hundred miles behind the expanding range of the African honey bees, the European and hybrid strains died out and the bees were essentially 100 percent African. How would this be explained in evolutionary genetics terms?

A) Gene flow is not occurring and therefore these are two separate species.
B) This is a natural consequence of the Hardy-Weinberg equilibrium.
C) Obviously the African bee genes are dominant over the European honey bee alleles.
D) Gene flow is occurring between these subspecies but the African bee is "ecologically better suited".
E) This can be understood as a classic case of genetic drift.

Question 12

Which of these conditions is NOT among the requirements of the Hardy-Weinberg equilibrium of allele frequencies in a population?

A) small population with genetic drift
B) no net migration of alleles into or out of the population
C) no net mutations
D) no selection of one genotype over another
E) random mating population

Question 13

If the mutation rate of individual genes is taken to be about one in 100,000 genes per cell cycle across many organisms, we might expect evolution to proceed at a consistent rate for various forms of life. Which factor could make the accumulation of gene mutations faster or slower among different organisms?

A) Organisms with more genes will likely have more mutations per generation.
B) More selection of mutations can occur in a shorter period of time for bacteria that replicate each twenty minutes than for humans with a (roughly) 20-year generation span.
C) Organisms vary in the proportion of DNA that is active and in the percent of loci that have multiple alleles.
D) All of the choices are correct.

Question 14

Mutations that result in resistance to specific antibiotics in bacterial organisms occur

A) only when the bacteria are exposed to the drug to which they become resistant.
B) more often when the bacteria are exposed to the drug.
C) at any time, even when the bacteria are not exposed to the drug.
D) only when the bacteria are exposed to radiation or other mutagens.

Question 15

Which statement is NOT true about natural selection?

A) Directional selection occurs when one extreme phenotype is favored over another different extreme phenotype.
B) Stabilizing selection favors an intermediate phenotype over either of the extreme phenotypes.
C) Disruptive selection favors both of the extreme phenotypes over the intermediate phenotype.
D) Directional selection leads to improved selection in a stable environment.
E) Disruptive selection leads to polymorphism, favoring different forms of the same species.

Question 16

If the Hardy-Weinberg equilibrium is met, what is the net effect?

A) evolution leading to a population better adapted to an unchanging environment
B) evolution leading to a population better adapted to a changing environment
C) very slow and continuous evolution with no increased adaptation
D) no evolution because the alleles in the population remain the same

Question 17

A certain species of butterfly varies in color from white to dark blue. The birds found in the same area feed on the white or lightly colored butterflies, leaving butterflies that are darkly colored. This may result in what type of selection?

A) stabilizing selection
B) disruptive selection
C) directional selection

Question 18

The most common source of genetic variation in sexually reproducing organisms is

A) mutation.
B) recombination of alleles through meiosis and fertilization.
C) duplication of chromosomes.
D) duplication of genes.

Question 19

If two adjacent populations of the same species show gene flow, then the two populations will

A) become more similar in their gene pools.
B) become isolated from each other.
C) develop into different species.
D) adapt to different conditions and become separate.

Question 20

What do the Founder Effect and the Bottleneck Effect have in common?

A) both the Founder Effect and the bottleneck effect result from mutation
B) both the Founder Effect and the bottleneck effect result from increase gene flow
C) both the Founder Effect and the bottleneck effect are examples of disruptive selection
D) both the Founder Effect and the bottleneck effect occur by chance

Question 21

Scientists have studied, in detail, the evolution of the peppered moth, Biston betularia, over the last two hundred years. The peppered moths rest on tree trunks and are a tempting treat for birds in the area. In the mid -1800's the trees in their England habitat were covered with lichens, which are a light, grayish - green color. Although color variations occurred, the vast majority of the moths were light-colored. Because their light coloration effectively camouflaged them against the lichens-covered trees, they were not as easily seen by birds as darker colored moths. The light colored moths flourished.
The environment changed, as the Industrial Revolution progressed. By 1900, the lichens had died and trees were coated with soot due to the industrial pollution. The lighter colored moths were no longer 'hidden' in their environment, and in fact, were easily seen by their predators. Their numbers dwindled. At the same time, the darker-colored moths flourished because of their ability to hide on the darkened trees.
As environmental standards have been implemented, environmental conditions have shifted, allowing lichens to grow on tree trunks.
a. What type of selection is this?
b. What is the agent of selection?
c. What alleles were favored in the clean environment? The polluted environment?

Question 22

Over the course of millions of years various environments have changed. As grasslands slowly took the place of forests the inhabitants were forced to adapt or they went extinct. During this time period the horse evolved from a small cat sized creature to the size of the modern horses we see today. This is an example of which type of natural selection?

A) directional
B) disruptive
C) stabilizing
D) The horse did not undergo any type of Natural Selection during the course of its evolution.
E) The horse has not been on the Earth for millions of years.

Question 23

In a population, the allele frequency for red flower color remained at 0.7 and the allele frequency for white flower remained at 0.3 for six generations. This ____ an example of a Hardy-Weinberg equilibrium in that ___________.

A) is not, evolution occurred
B) is, evolution did not occur
C) is, evolution occurred
D) is not, evolution did not occur

Question 24

Natural selection can maintain genetic variation by favoring heterozygous genotypes. In equatorial Africa, the best genotype to have for hemoglobin is heterozygous (HbA / HbS). In the United States of America, there is no advantage to the heterozygous genotype. HbA codes for normal hemoglobin, whereas HbS codes for an abnormal hemoglobin that causes red blood cells to become distorted in shape (sickle cell). Explain why the heterozygous state is advantageous in Africa, but not in the USA. What has happened to the sickle cell allele in Africa? What has happened to the sickle cell allele in the United States?

Question 25

Social research indicates that a person is most likely to marry someone from the same village or city, or a high school or college classmate. Therefore, the Hardy-Weinberg equilibrium does not apply well to human populations because

A) allelic changes in one direction are balanced by changes in the opposite direction.
B) there is no directional trend in selection of mates since most individuals marry someone.
C) individuals are not pairing up by chance across the whole population.
D) this increases gene flow.
E) we accumulate adaptive traits that improve the population.

Question 26

Amish populations in Lancaster County, Pennsylvania have high rates of a rare form of dwarfism. The recessive allele that codes for this disorder is found in 1 of 14 individuals in this Amish population, in contrast to 1 in 1,000 in the general population. In Ohio, an Amish population suffers with higher than normal rates of cystic fibrosis and a host of other genetic diseases so rare that some have not yet been named. What factors have caused such severe genetic problems in these two communities?

Question 27

Which of the following is required for natural selection to occur in a population?

A) variation in the population
B) inheritance of variation through genetic differences
C) differential reproduction so that the more fit individuals have more offspring that survive to reproduce
D) accumulation of adaptive traits so that they increase in the population
E) All of the choices are required.

Question 28

In the case of the peppered moths in England, when Kettlewell set up cameras to document that more white or black moths were eaten by birds on clean or sooty trees, he was verifying which factor involved in evolution by natural selection?

A) The organisms vary in traits and that these traits may be acquired during a lifetime.
B) The variation is inherited.
C) More young are born than can survive, so there will always be competition.
D) Some individuals are better adapted to a particular environment than other individuals.

Question 29

Define and give an example of assortative mating. Will this affect genotype frequencies? If so, predict how genotype frequencies will be affected in a population if assortative mating persists.

Question 30

The black bellied seed cracker, Pyrenestes, is a West African finch. Within the same geographic region, two subspecies of the finch are found. One subspecies has a large beak, which is efficient at cracking the hard seeds of the sedge, Scleria verrucosa. The other subspecies has a small beak, which is more efficient at eating the soft seeds of the sedge, Scleria goossensii. What type of selection occurred to produce this situation? Explain what a population distribution graph would look like that would depict this type of selection.

Question 31

The northern elephant seal was hunted almost to extinction during the 18^th and 19^th centuries. Less than 100 seals were left to contribute to the gene pool of their future generations. Since the early 20^th century, the elephant seals have been protected by law in both the U.S. and Mexico. Over 100,000 seals now inhabit the western shores of North America, all related to the small population that survived the slaughter of hunters.
Scientists fear the elephant seals may be more susceptible to disease and pollution due to a ______.

A) heterozygous advantage
B) disruptive type of selection
C) Founder Effect
D) Bottleneck Effect

Question 32

What is the relative biological fitness of an individual who is heterozygous for sickle-cell disease who lives in Central Illinois vs. an individual who is heterozygous and lives in South Africa?

Question 33

If early Viking explorers in Greenland and North America had survived and become the main ancestors of early North American settlers, rather than the mixture of immigrants from across Europe and other continents, today there would be a much higher incidence of Nordic traits in the U.S. population. Such a scenario would demonstrate

A) gene flow from continent to continent.
B) the bottleneck effect.
C) genetic drift among the original Viking explorers.
D) directional selection.
E) the Founder Effect.

Question 34

A dominant allele is found in a population with a frequency of 0.8. As the environment begins to change, the dominant allele is not favored. Scientists find that the frequency of the dominant allele decreases by half each generation. What are the allele, genotype and phenotype frequencies before and one generation after the population begins to change. Is Hardy-Weinberg equilibrium maintained?

Question 35

While we have seen how natural selection and the use of pesticides can lead to the development of resistant varieties of insects, two economically important flies, the Mediterranean fruit fly (Medfly) and the screwworm fly, can be driven to local extinction by the continuous release of sterile flies of those species. The critical factor is that the female of these species only mates once. But which of the following is/are also necessary for sterile release to work?

A) The target species is truly just one species.
B) The insect can be raised artificially in large numbers.
C) The insects to be released can be sterilized with radiation without affecting their ability to attract a mate in the wild.
D) All of the choices are correct.

Question 36

A population was surveyed to determine the percentage of individuals with detached earlobes and attached earlobes. 16% of the population was found to have attached earlobes, a trait coded for by a recessive allele. Calculate the allele, genotype and phenotype frequencies of the population, assuming Hardy-Weinberg equilibrium is maintained.

Question 37

The difference in temperature preference between two populations of Daphnia water fleas is due to a mutation. The original population prefers temperatures near 20 $\degree$ C, while the mutant population prefers temperatures between 25 $\degree$ C and 30 $\degree$ C. Predict how natural selection might affect the geographical distribution of these two populations.

Question 38

Hospital data shows that human infants born with an intermediate birth weight have a better chance of survival than those that weigh much less or much more than usual. Larger than normal babies may have a difficult delivery, while smaller than normal babies may not be fully developed. What type of selection is occurring? Is the variability in birth weight in human populations increasing or decreasing? Explain what the normal population distribution would look like on a scale of 1 - 20. Explain what the distribution would look like after many generations and indicate the phenotype selected.

Question 39

Explain why male baboons have evolved to be larger than the females of the species?

Question 40

Scientists have studied, in detail, the evolution of the peppered moth, Biston betularia, over the last two hundred years. The peppered moths rest on tree trunks and are a tempting treat for birds in the area. In the mid -1800's the trees in their England habitat were covered with lichens, which are a light, grayish - green color. Although color variations occurred, the vast majority of the moths were light-colored. Because their light coloration effectively camouflaged them against the lichens-covered trees, they were not as easily seen by birds as darker colored moths. The light colored moths flourished.
The environment changed, as the Industrial Revolution progressed. By 1900, the lichens had died and trees were coated with soot due to the industrial pollution. The lighter colored moths were no longer 'hidden' in their environment, and in fact, were easily seen by their predators. Their numbers dwindled. At the same time, the darker-colored moths flourished because of their ability to hide on the darkened trees.
As environmental standards have been implemented, environmental conditions have shifted, allowing lichens to grow on tree trunks.
Describe what the initial normal population curve would look like before pollution. Describe what the population curve would look like after the Industrial Revolution and indicated what phenotype was favored.

Question 41

While studying gull egg laying abilities a researcher noted that the birds laid an average of 7 - 9 eggs per clutch at the beginning of the study. After studying the population for 15 generations the researcher noted that the birds now laid an average of 3- 4 eggs per clutch. What type of natural selection is occurring in the population of gulls? rev: 12_12_2013_QC_42519

A) stabilizing
B) directional
C) disruptive
D) There is no selection occurring in this population.

Question 42

The Founder Effect is an example of genetic drift in which rare alleles occur at a higher frequency in a population isolated from the general population.

Question 43

The bottleneck effect is thought to be responsible for the loss of genetic variability in a species.

Question 44

Which of the following conditions is necessary to maintain the Hardy-Weinberg equilibrium?

A) random mating
B) mutations
C) sexual selection
D) gene flow
E) genetic drift

Question 45

Another student proposes that handedness could just as easily be passed to children by how the parents carry the child and interact with it, a learning process that may perpetuate from the parents' handedness. Assuming all parents and children are expressing their "true handedness," the occurrence of which case below would cast the most serious doubt on a simple genetic basis for handedness, with left-handedness recessive?

A) Two right-handed parents have a left-handed child.
B) Two left-handed parents have a right-handed child.
C) Left-handed parents only have left-handed children.
D) Right-handed parents only have right-handed children.
E) None of the choices are correct.

Question 46

An allele becomes the most common allele in a population by becoming the dominant allele.

Question 47

What is the most plausible explanation for why the male of most bird species have elaborate plumage and mating rituals?

A) sexual selection
B) genetic mutations
C) gene flow
D) natural selection

Question 48

Which of the following conditions is not necessary to maintain the Hardy-Weinberg equilibrium?

A) large gene pool
B) no migration
C) mutation
D) random mating
E) no selection

Question 49

Which genotype is most likely to survive in a region of the world that contains malaria?

A) homozygous recessive for hemoglobin shape
B) heterozygous for hemoglobin shape
C) homozygous dominant for hemoglobin shape
D) all genotypes have the same potential for survival in a region that contains malaria

Question 50

British land snails are an example of disruptive selection. In the grassy fields, the light-banded snails escape bird predators. In the darker forest, the dark snails survive and the light-banded snails are eaten. The different colored snails have the opportunity to interact and breed across the British landscape. Why doesn't this "disruptive selection" eventually lead to two separate species?

A) There is no reproductive isolation to prevent gene flow.
B) They are already two separate species, and the intermediate forms are hybrids.
C) The color forms are probably not genetically determined.
D) There must be some unknown factor producing an equal stabilizing selection "to hold the species together."
E) This will result in the formation of two species if given long enough time.

Question 51

Which of the following reflect(s) the likely presence of (a) gene mutation(s)?

A) Fruit flies subjected to intense radiation produce a wider array of variable offspring.
B) A chemical leaking from the surface of an old abandoned coal mine alters a regulatory gene so that a cricket nymph develops an extra set of eyes.
C) The bacteria that cause gonorrhea, a common sexually transmitted disease, have previously been killed by penicillin; however, after continuous usage of the antibiotic, penicillin-resistant strains are now becoming prevalent.
D) Radiation causes an alteration in a DNA nucleotide sequence, which is discovered when mapped, but which appears to be neither increasing nor decreasing in successive generations.
E) All of the choices are correct.

Question 52

A population of organisms that reproduce asexually without gametes from other individuals will display more variation than a population that reproduces sexually. This results in a greater likelihood of the population evolving.

Question 53

Gene mutation occurs at any time, without respect to the mutation's adaptive value or benefit to the organism.

Question 54

The Hardy-Weinberg equilibrium is usually met in populations in changing environments.

Question 55

Which of the following examples will help maintain diversity within a population?

A) lack of mutations within the population
B) random mating
C) absence of migration
D) natural selection

Question 56

What type of selection is occurring in a population if the distribution graph shifts from the left end of the spectrum to the far right end?

A) directional
B) stabilizing
C) disruptive
D) Populations do not undergo selection, they are fixed.