Chpt. 22,23,24 Mastering Biology
Given a population that contains genetic variation, what is the correct sequence of the following events under the influence of natural selection?1. Well-adapted individuals leave more offspring than do poorly adapted individuals.2. A change occurs in the environment.3. Genetic frequencies within the population change.4. Poorly adapted individuals have decreased survivorship.
2 → 4 → 1 → 3
Of the 59 matings in the experimental groups, how many were between like-adapted flies (flies adapted to the same medium)?
42
A farmer wishes to develop a strain of high-yield corn that is also resistant to drought. He has the following individuals from the current year's crop:Individual A—Yield: 179 bushels/acre; drought resistance: highIndividual B—Yield: 220 bushels/acre; drought resistance: lowIndividual C—Yield: 185 bushels/acre; drought resistance: mediumIndividual D—Yield: 140 bushels/acre; drought resistance: highIndividual E—Yield: 200 bushels/acre; drought resistance: mediumWhich of the following crosses would produce the highest corn yield with the highest resistance to drought?
A and E
Which of the following organisms could be produced by artificial selection?
A cow that produces a large quantity of milk.
In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of allele a is 0.2. What is the frequency of individuals that are heterozygous for this allele?
0.32
What is the frequency of the A1A2 genotype in a population composed of 20 A1A1 individuals, 80 A1A2 individuals, and 100 A2A2 individuals?
0.4
In peas, a gene controls flower color such that R = purple and r = white. In an isolated pea patch, there are 36 purple-flowering plants and 64 white-flowering plants. Assuming Hardy-Weinberg equilibrium, what is the value of q for this population?
0.80
In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of allele a is 0.1. What is the frequency of individuals with AA genotype?
0.81
Plant species F has a diploid number of 8. Plant species G has a diploid number of 10. What would be the diploid number of an allopolyploid hybrid of species F and species G?
18
Which of the numbers in this tree represents the most recent common ancestor of amphibians and lizards?
2
Which of these conditions are always true of populations evolving due to natural selection?Condition 1: The population must vary in traits that are heritable.Condition 2: Some heritable traits must increase reproductive success.Condition 3: Individuals pass on most traits that they acquire during their lifetime
Conditions 1 and 2
Long necks make it easier for giraffes to reach leaves high on trees, while also making them better fighters in "neck wrestling" contests. In both cases, which kind of selection appears to have made giraffes the long-necked creatures they are today?
Directional selection
Black-bellied seedcrackers have either small beaks (better for eating soft seeds) or large beaks (better for hard seeds). There are no seeds of intermediate hardness; therefore, which kind of selection acts on beak size in seedcrackers?
Disruptive selection
Which type of selection tends to increase genetic variation?
Disruptive selection
Which statement about the beak size of finches on the island of Daphne Major during prolonged drought is true?
Each bird's survival was strongly influenced by the depth and strength of its beak as the drought persisted.
True or false? Heterozygote advantage refers to the tendency for heterozygous individuals to have better fitness than homozygous individuals. This higher fitness results in less genetic variation in the population.
False
Which of the following statements is supported by the data from the control group matings?
Flies were about as likely to mate with flies from different starch-adapted populations as with flies from their own starch-adapted population.
Which of the following are basic components of the Hardy-Weinberg model?
Frequencies of two alleles in a gene pool before and after many random matings
How did Dr. Allison test his hypothesis that sickle cell disease was connected to malaria?
He evaluated blood samples for malaria parasites and the presence of sickle cells. He expanded his study area beyond Kenya to the rest of East Africa to see if malaria and sickle disease were connected.
What genotype frequencies are expected under Hardy-Weinberg equilibrium for a population with allele frequencies of p = 0.8 and q = 0.2 for a particular gene?
The expected genotype frequencies are 0.64, 0.32, and 0.04 for A1A1, A1A2 , and A2A2 , respectively.
What is the frequency of the A1 allele in a population composed of 20 A1A1 individuals, 80 A1A2 individuals, and 100 A2A2 individuals?
The frequency of the A1 allele is 0.3.
Which of the following statements is not a part of the Hardy-Weinberg principle?
The genotype frequencies in the offspring generation must add up to two.
In Darwin's tree of life, each fork in the tree represents ________.
the most recent common ancestor of the subsequent branches
Which factor is most important for explaining why there are equal numbers of snapping shrimp species on either side of the isthmus?
the relative shortness of time they have been separated
Which of the following statements describes mechanical isolation prezygotic barrier?
two snails have shells that spiral in different directions
If x indicates the fossils of two closely related species, neither of which is extinct, then their remains may be found in how many of these strata?
two strata
Which of the five species, labeled V-Z, is the common ancestor of the fewest number of species?
v
Which of the five common ancestors, labeled V-Z, is the common ancestor of the greatest number of species, both living and extinct?
y
Which one of the following conditions would allow gene frequencies to change by chance?
small populations
Based on the information presented in the accompanying figure, when both finches are found on the same island, what is the most likely factor to determine the difference in beak size?
Competition
In the accompanying diagram, the original population of a species of fish in a small lake that lacks predators is shown at the top. After separation by a land mass, the figure at the bottom left of the diagram shows the resulting change. Each color represents a different species. Allopatric speciation occurs when gene flow is disrupted through physical isolation of the original population. Although generally less common, sympatric speciation can occur among individuals in a population living in the same area, such as seen in the bottom right of the figure. Which of the following scenarios would most likely cause sympatric speciation to occur?
A mutation that resulted in green coloration affected female mate choice.
Which conclusion can be drawn from this evolutionary tree?
A single clade (that is, a group of species that share a common ancestor) can include species that formed by gradualism and other species that formed by punctuated equilibrium.
The Panama Canal was completed in 1914, and its depth is about 50 feet. After 1914, snapping shrimp species from which habitats should be most likely to form hybrids as the result of the canal?
A1 and B1
Which habitats should harbor snapping shrimp species with the greatest degree of genetic divergence from each other?
A5 and B5
Which term describes a trait that increases an individual's ability to survive in a particular environment?
Adaptation
_____ is rapid speciation under conditions in which there is little competition.
Adaptive radiation
Why should we not view lactose intolerance as a disease in adult humans?
Adult humans did not consume dairy products until fairly recently in our evolutionary history.
You sample a population of butterflies and find that 56% are heterozygous at a particular locus. What should be the frequency of the recessive allele in this population?
Allele frequency cannot be determined from this information.
Which of the following statements best explains why modification or change in an organ or tissue during the lifetime of an individual is not inherited?
Characteristics acquired during an organism's life are generally not passed on through genes.
A river could potentially be a geographic barrier that causes allopatric speciation. Which of these organisms is LEAST likely to overcome such a barrier?
small rodents
In 1949, Dr. Tony Allison observed a high frequency of Kenyans carrying the sickle cell allele in coastal areas and near Lake Victoria, but a lower frequency in the highlands. What did he hypothesize?
He hypothesized that there was a connection between malaria and sickle cell disease.
Which term describes the ability of a trait to be passed on to offspring?
Heritability
Among known plant species, which of these have been the two most commonly occurring phenomena that have led to the origin of new species?
sympatric speciation and polyploidy
When dark-colored fur gives mice a 1% competitive advantage and 1% of the population begins with dark fur, in about 1000 years, 95% of the population will have dark fur. Which of the following statements is true?
If dark-colored rock pocket mice had a competitive advantage of 0.1%, it would take longer for 95% of the population to have dark fur.
How does Dr. Allison's work provide an example of natural selection in humans?
In areas with malaria, individuals with one sickle cell allele reproduced at higher rates than those with no sickle cell alleles. In areas without malaria, individuals with two sickle cell alleles reproduced at lower rates than those without sickle cell disease.
A narrow hybrid zone separates the toad species Bombina bombina and Bombina variegata. What is true of those alleles that are unique to the parental species?
The alleles' heterozygosity should be higher among the hybrid toads than in toad populations distant from the hybrid zone.
Starting from the wild mustard Brassica oleracea, breeders have created the strains known as Brussels sprouts, broccoli, kale, and cabbage. Therefore, which of the following statements is correct?
In this wild mustard, there is enough heritable variation to permit these different varieties.
In some populations, 1 in 500 people have sickle cell disease. What reason does the film give for why a potentially deadly, inherited disease is found at such high frequencies?
Individuals with one sickle cell allele are protected from malaria and do not have sickle cell disease, thus keeping the allele in the population.
If the finch G. fortis established a population on Los Hermanos, based on the information shown in the graph, what would you predict would happen to the beak depth of G. fuliginosa over time?
The beak depth would decrease.
The sequence of events illustrated in this figure results in a fertile hybrid plant called an allopolyploid. Which of the following statements is the most complete description of an allopolyploid?
It contains more than two sets of chromosomes, which are derived from two species.
What role does nondisjunction play in the formation of a fertile allopolyploid hybrid?
It doubles the chromosome number in the hybrid.
Why is the enzyme lactase necessary to digest dairy products?
Lactase breaks down lactose into smaller molecules that can be absorbed by the cells that line the small intestine.
Most people are lactose intolerant as adults, but nearly everyone produces sufficient lactase as an infant. However, in some cases, genetic mutations can occur that make an infant lactose intolerant. From an evolutionary perspective -- over thousands of years -- why would lactose intolerance in infants be very rare in the population?
Lactose intolerant infants could not digest breast milk and therefore usually died, never having the chance to pass the mutation on to their children.
Which pair of chickens should a farmer breed to produce larger chickens?
Large hen, large rooster
What do these comparisons suggest about when natural selection favored left-mouthed individuals over right-mouthed individuals?
Left-mouthed individuals were selected for when right-mouthed individuals were more common, and vice versa.
This phylogenetic tree illustrates the evolutionary relationships of tetrapods and was constructed using both anatomical and DNA sequence data. Using evidence from this tree, which statement most accurately reflects the relationship of mammals to birds and amphibians?
Mammals are more closely related to birds because they share a more recent common ancestor.
Gametes from two plant species combine and produce a haploid zygote, and that zygote develops into a haploid, hybrid plant. Why is the hybrid plant sterile?
Meiosis cannot occur. The cells do not contain homologous chromosomes.
The restriction enzymes of bacteria protect the bacteria from successful attack by bacteriophages, whose genomes can be degraded by the restriction enzymes. The bacterial genomes are not vulnerable to these restriction enzymes because bacterial DNA is methylated. This situation selects for bacteriophages whose genomes are also methylated. As new strains of resistant bacteriophages become more prevalent, this in turn selects for bacteria whose genomes are not methylated and whose restriction enzymes instead degrade methylated DNA. Over the course of evolutionary time, what should occur?
Methylated and nonmethylated strains should be maintained among both bacteria and bacteriophages, with ratios that vary over time.
For 1981, 1987, and 1990, how does the frequency of left-mouthed breeding adults compare to the frequency of left-mouthed individuals in the entire population?
Most of the breeding adults had the opposite phenotype of that which was most common in the population.
Which of the following evolutionary forces could create new genetic information in a population?
Mutation
What does Dr. Carroll mean when he says, "while mutation is random, natural selection is not"?
Natural selection acts on traits. Mutations for advantageous traits are more likely to be passed on to the next generation. Natural selection favors some mutations.
Which of the following statements about natural selection is true?
Natural selection favors individuals that reproduce more than others.
Is this population in Hardy-Weinberg equilibrium?
No; there are more homozygotes than expected.
The peppered moth provides a well-known example of natural selection. The light-colored form of the moth was predominant in England before the Industrial Revolution. In the mid-19th century, a dark-colored form appeared. The difference is produced by a dominant allele of one gene. By about 1900, approximately 90% of the moths around industrial areas were dark colored, whereas light-colored moths were still abundant elsewhere. Apparently, birds could readily find the light moths against the soot-darkened background in industrial areas and, therefore, were eating more light moths. Recently, use of cleaner fuels has greatly reduced soot in the landscape, and the dark-colored moths have been disappearing. Should the two forms of moths be considered separate species?
No; they still can interbreed.
Which of the following evolutionary forces consistently results in adaptive changes in allele frequencies?
Selection
Compare sickle cell disease and malaria.
Sickle cell disease and malaria are both potentially lethal diseases.
From a study of soapberry bugs (Jadera haematoloma), a similar theme emerges that reflects the process of natural selection that Charles Darwin observed in the Galapagos finches. In order for soapberry bugs to feed, their "beak" length must match the depth of seeds in the balloon vine fruit. In central Florida, the native balloon vine has become rare and the Goldenrain tree, an introduced species from Asia, has become the main food source for soapberry bugs. Carroll and Boyd (1992) compared beak lengths of soapberry bug populations that fed on the native balloon vine in southern Florida with central Florida populations that fed on the Goldenrain tree, whose seeds are much closer to the fruit surface than the seeds of the plump balloon vine fruit. The researchers compared these data with the average beak length in museum specimens collected from the two areas before the Goldenrain tree was introduced (indicated by the red arrows). Which of the following suggestions is most likely true regarding the results of this study?
Soapberry bugs with shorter beaks had a selective advantage in Central Florida because they were better able to feed on Goldenrain fruits.
Small Aristelliger lizards have difficulty defending territories, but large lizards are more likely to be preyed upon by owls. Which kind of selection acts on the adult body size of these lizards?
Stabilizing selection
Women often have complications during labor while giving birth to very large babies, whereas very small babies tend to be underdeveloped. Which kind of selection is most likely at work regarding the birth weight of babies?
Stabilizing selection
What can you conclude about the lungfish lineage based on this tree?
The most recent common ancestor of lungfishes and amphibians did not have an amnion.
The following question is based on information from Frank M. Frey, "Opposing Natural Selection from Herbivores and Pathogens May Maintain Floral-Color Variation in Claytonia virginica (Portulacaceae)," Evolution 58(11), 2004: 2426-37.Claytonia virginica is a woodland spring herb with flowers that vary from white to pale pink to bright pink. Slugs prefer to eat pink-flowering over white-flowering plants (due to chemical differences between the two), and plants experiencing severe herbivory are more likely to die. The bees that pollinate this plant also prefer pink to white flowers, so that Claytonia with pink flowers have greater relative fruit set than Claytonia with white flowers. A researcher observes that the percentage of different flower colors remains stable in the study population from year to year. Given no other information, if the researcher removes all slugs from the study population, what do you expect to happen to the distribution of flower colors in the population over time?
The percentage of pink flowers should increase over time.
If a person has two normal copies of the hemoglobin allele, which statements are true?
The person is susceptible to malaria.The person is homozygous at the hemoglobin locus.
Predict what will happen to the frequency of the sickle cell allele in areas where malaria has been eradicated.
The sickle cell allele will decrease in frequency.
Which of the following statements is best supported by the data on matings in the experimental groups?
The starch-adapted flies and maltose-adapted flies are not different species, but a reproductive barrier is forming between the populations. Submit
How do lactase supplements help people who are lactose intolerant?
The supplements provide the enzyme that breaks down the lactose in dairy products.
Most causes of speciation are relatively slow, in that they may take many generations to see changes, with the exception of _____.
polyploidy
Modern cetaceans, the taxonomic group that includes whales, dolphins, and porpoises, evolved from land mammals. However, it has only been within the past few decades that transitional fossils have been found that have shed light on cetacean hindlimb reduction. DNA data suggest that cetaceans are most closely related to Hippos, which are even-toed ungulates. Other even-toed ungulates include deer, pigs, camels, and cows. Which statement describes most accurately how the early cetacean,Pakicetus, fossil ankle bones shown in the figure supports the hypothesis that cetaceans are closely related to even-toed ungulates?
The two humps on the bottom end of the Pakicetus ankle bone is a distinguishing feature shared with other even-toed ungulates.
In a bell-shaped curve, the x-axis (horizontal direction) of the graph represents which of the following?
The value of a particular characteristic; characteristics of an organism can include such traits as size and color.
Why do dark-colored rock pocket mice on dark lava flows have white bellies?
There is no selection for dark bellies by visual predators.
A similar control experiment was performed with flies adapted to maltose, and similar results were obtained. What were these control experiments testing?
These control experiments tested whether flies were more likely to choose mates from their own population than from another population adapted to the same medium.
Why did dark-colored rock pocket mice first appear in a population of light-colored rock pocket mice?
They have a genetic mutation that affects their fur color.
Lactose intolerance in infants is more common in the population today than it was a hundred years ago. Why?
Today there are alternatives to breast milk, such as lactose-free formula and soy milk, so lactose intolerant infants can survive. Submit
Which of the following are testable hypotheses that could explain the researchers' data? Select all that apply.
Traits that help individuals avoid being hit by cars have evolved through natural selection in the cliff swallow population.Scavenger population sizes have increased, and more road-killed swallows get eaten before they can be found.The population size of cliff swallows living near roads has decreased over time.
True or false? The Hardy-Weinberg model makes the following assumptions: no selection at the gene in question; no genetic drift; no gene flow; no mutation; random mating.
True
Over long periods of time, many cave-dwelling organisms have lost their eyes. Tapeworms have lost their digestive systems. Whales have lost their hind limbs. How can natural selection account for these losses?
Under particular circumstances that persisted for long periods, each of these structures presented greater costs than benefits.
In the lab, Nachman examined dark mice from two different populations living hundreds of miles apart. The mice looked nearly identical. Their dark color was caused by two different genes. What does this tell you?
Under very similar conditions, natural selection can favor very similar adaptations.Dark fur color evolved independently on each lava flow.Two completely different mutations in two separate genes can generate the same phenotype.There are at least two genes involved in creating dark mouse fur.
HIV's genome of RNA includes the code for reverse transcriptase (RT), an enzyme that acts early in infection to synthesize a DNA genome off of an RNA template. The HIV genome also codes for protease (PR), an enzyme that acts later in infection by cutting long viral polyproteins into smaller, functional proteins. Both RT and PR represent potential targets for antiretroviral drugs. Drugs called nucleoside analogs (NA) act against RT, whereas drugs called protease inhibitors (PI) act against PR.Which of the following treatment options would most likely avoid the evolution of drug-resistant HIV (assuming no drug interactions or side effects)?
Use moderate doses of NA and two different PIs at the same time for several months.
Mutations are always __________.
a change in an individual's DNA
In 1983, a population of dark-eyed junco birds became established on the campus of the University of California, San Diego (UCSD), which is located many miles from the junco's normal habitat in the mixed-coniferous temperate forests in the mountains. Juncos have white outer tail feathers that the males display during aggressive interactions and during courtship displays. Males with more white in their tail are more likely to win aggressive interactions, and females prefer to mate with males with more white in their tails. Females have less white in their tails than do males, and display it less often. (Pamela J. Yeh. 2004. Rapid evolution of a sexually selected trait following population establishment in a novel habitat. Evolution 58[1]:166-74.)The UCSD campus male junco population tails were, on average, 36% white, whereas the tails of males from nearby mountain populations averaged 40-45% white. If this observed trait difference were due to a difference in the original colonizing population, it would most likely be due to ________.
a founder effect
Mass extinctions create conditions that promote _____.
adaptive radiation
The appearance of an evolutionary novelty promotes _____.
adaptive radiation
The different finch species found on the Galápagos Islands probably arose as a result of _____.
adaptive radiation
Feathers either play a role, or may have played a role, in _____.
all of these
Which of the following lineages are not nested within the reptiles?
amphibians
According to the biological species concept, for speciation to occur, ________.
at least one gene, affecting one reproductive barrier, must change
When should a lactase supplement be taken in order to be most effective, and why?
at the same time the dairy product is consumed, so that the lactase will be in contact with the lactose
Which of the various species concepts distinguishes two species based on the degree of genetic exchange between their gene pools?
biological
If biological species are defined in terms of reproductive compatibility, the formation of a new species hinges on ________.
reproductive isolation
In a very large population, a quantitative trait has the following distribution pattern. If there is no gene flow, the curve shifts to the left or to the right, and the population size consequently increases over successive generations, which of the following is most likely occurring?
directional selection
Three-spined stickleback fish (Gasterosteus aculeatus) show substantial heritable variation in gill-raker length related to differences in their diets. Longer gill rakers appear to function better for capturing open-water prey, while shorter gill rakers function better for capturing shallow-water prey. Which of the following types of selection is most likely to be found in a large lake (open water in the middle and shallow water around the sides) with a high density of these fish?
disruptive selection
How many distinct species, both living and extinct, are depicted in this tree?
eleven
Cystic fibrosis is a genetic disorder in homozygous recessives that causes death during the teenage years. If 9 in 10,000 newborn babies have the disease, what are the expected frequencies of the dominant (A1) and recessive (A2) alleles according to the Hardy-Weinberg equation?
f(A1) = 0.9700, f(A2) = 0.0300
The restriction enzymes of bacteria protect the bacteria from successful attack by bacteriophages, whose genomes can be degraded by the restriction enzymes. The bacterial genomes are not vulnerable to these restriction enzymes because bacterial DNA is methylated. This situation selects for bacteriophages whose genomes are also methylated. As new strains of resistant bacteriophages become more prevalent, this in turn selects for bacteria whose genomes are not methylated and whose restriction enzymes instead degrade methylated DNA. The outcome of the conflict between bacteria and bacteriophage at any point in time results from _____.
frequency-dependent selection
What does the biological species concept use as the primary criterion for determining species boundaries?
gene flow
Based on this tree, which of the following groups of organisms is most closely related to crocodiles?
hawks
Structures as different as human arms, bat wings, and dolphin flippers contain many of the same bones, which develop from similar embryonic tissues. These structural similarities are an example of _____.
homology
Which postzygotic barriers prevent formation of hybrids beyond the first generations?
hybrid breakdown
In which country would you most likely find a higher incidence of lactase persistence?
in a Scandinavian country where people historically raised dairy cattle and made cheese
After the drought of 1977, researchers hypothesized that on the Galápagos Island Daphne Major, medium ground finches with large, deep beaks survived better than those with smaller beaks because they could more easily crack and eat the tough Tribulus cistoides fruits. A tourist company sets up reliable feeding stations with a variety of bird seeds (different types and sizes) so that tourists can get a better look at the finches. Which of these events is now most likely to occur to finch beaks on this island?
increased variation in beak size and shape over time
HIV's genome of RNA includes the code for reverse transcriptase (RT), an enzyme that acts early in infection to synthesize a DNA genome off of an RNA template. The HIV genome also codes for protease (PR), an enzyme that acts later in infection by cutting long viral polyproteins into smaller, functional proteins. Both RT and PR represent potential targets for antiretroviral drugs. Drugs called nucleoside analogs (NA) act against RT, whereas drugs called protease inhibitors (PI) act against PR.Which mechanism produces variation for evolution by shuffling existing alleles?
sexual reproduction
It has been observed that organisms on islands are different from, but closely related to, similar forms found on the nearest continent. This is taken as evidence that ____.
island forms are descended from mainland forms
An amnion is a shared homologous characteristic for which of the following lineages?
mammals crocodiles
Generation-to-generation change in the allele frequencies in a population is _____.
microevolution
Genetic variation ________.
must be present in a population before natural selection can act upon the population
Which of the following are causes of evolutionary change?
mutation natural selection gene flow genetic drift
In 1983, a population of dark-eyed junco birds became established on the campus of the University of California, San Diego (UCSD), which is located many miles from the junco's normal habitat in the mixed-coniferous temperate forests in the mountains. Juncos have white outer tail feathers that the males display during aggressive interactions and during courtship displays. Males with more white in their tail are more likely to win aggressive interactions, and females prefer to mate with males with more white in their tails. Females have less white in their tails than do males, and display it less often. (Pamela J. Yeh. 2004. Rapid evolution of a sexually selected trait following population establishment in a novel habitat. Evolution 58[1]:166-74.)The UCSD campus male junco population tails are about 36% white, whereas the tails of males from nearby mountain populations are about 40-45% white. The founding stock of UCSD birds was likely from the nearby mountain populations because some of those birds overwinter on the UCSD campus each year. Population sizes on the UCSD campus have been reasonably large, and there are significant habitat differences between the UCSD campus and the mountain coniferous forests; UCSD campus has a more open environment (making birds more visible) and a lower junco density (decreasing intraspecific competition) than the mountain forests. Given this information, which of the following evolutionary mechanisms do you think is most likely responsible for the difference between the UCSD and mountain populations?
natural selection
The higher the proportion of loci that are "fixed" in a population, the lower are that population's ________.
nucleotide variability and average heterozygosity
How can reproductive barriers form sympatric populations while their members remain in the same geographic area?
polyploidy
