exam 5
A gene in a randomly-mating population has two alleles (A,a), and 1 in 400 individuals in the population is homozygous recessive (aa). Calculate the frequency of heterozygotes (Aa) in the population.
0.095
A gene in a randomly-mating population has two alleles (A,a), and the allele frequency of A is 0.65. Calculate the frequency of homozygous recessive individuals (aa) in the population.
0.1225
If you examine a population for a particular gene where B represents the dominant allele and b represents the recessive allele, you find that the allele frequencies for this gene are p = 0.3 and q = 0.7. If this population is not evolving, what would be the frequency of the heterozygous genotype?
0.42
In a population of 75 mice, what would be the size of their gene pool for a particular gene?
150
In a population of 100 mice, if the recessive allele frequency is 0.25, how many copies of the recessive alleles are found in the population?
50
Why is gene transfer among bacteria significant to human health?
A gene carrying antibiotic resistance can be transferred among bacteria, decreasing the likelihood that the antibiotic is effective in treating certain diseases.
Select the scenarios that show how an organism's fitness is dependent on the environment. Select the TWO answers that are correct.
A population of field mice in the forest has lower survival rates than the population in the state park. A butterfly living in a wildflower field has higher reproduction rates than the same butterfly living in a wooded area.
All of Darwin's finches came from a single species with a "normal" beak. Which factor can explain the development of the variety of beaks seen in these finches today?
All of these factors help explain the variety of beaks.
Select the statement that describes how fitness and natural selection interact to lead to adaptation.
Alleles well-suited to the environment increase the fitness of organisms, allowing for higher survival and reproduction so that the beneficial alleles are passed on to future generations and increase in incidence in the population over time.
Antibiotic-resistant strains of bacteria tend to first be found in hospitals. Which factor explains why this is the case?
Antibiotics are more likely to be present in hospitals, thus selecting for resistant strains.
Which statement regarding drug-resistant bacteria is false?
Bacteria that are sensitive to antibiotics have a reproductive advantage in all environments.
Despite numerous hardships, Russel Wallace was not deterred, and he almost beat Darwin to publication of his work on evolution. Why does Darwin get most of the credit for the theory of evolution?
Darwin detailed a more complete account of evolution by natural selection in his paper.
Which statement regarding the dating of fossils is false?
Fossils can be dated using a microscope to examine tissue.
Organism XYZ has a DNA sequence of GGTATAGAGT. By examining the sequence of nucleotides below, determine which organism is most closely related to organism XYZ.
GGTATAGAGG
Select the scenarios that describe diversifying selection. Select the TWO answers that are correct.
In a patchy underwater habitat, light-colored oysters blend into the rocks and dark-colored oysters blend into the shadows. In a species of butterfly, both the white- and black-winged adults are toxic to predators, but the gray-winged butterflies are not.
Select the scenarios that describe stabilizing selection. Select the TWO answers that are correct.
In chickens, eggs of intermediate weight show the highest rate of hatching. Cats with short tails do not balance well, and cats with long tails are clumsy.
Darwin's finches came from a mainland species where some individuals were able to move to the islands and then spread from one island to another. Is the genetic diversity of the new population of finches on the Galápagos increased or decreased in relation to the population on the mainland, and what is this an example of?
It decreased their genetic diversity because this represents an example of genetic drift.
What happens to the parent cell during binary fission?
It elongates, replicates its DNA, and divides in two.
A bacterial cell that is resistant to a particular antibiotic may spend a large amount of energy producing the modified proteins that are needed for resistance. In such a case, what would be the effect on this cell's fitness if no antibiotic was present?
Its fitness would be lower than other strains that lack resistance because it is spending energy that the resistant strains can use for other purposes, such as reproduction.
Researchers often use mice to evaluate potential medications for treating human disease. If a medication is successful in the mouse model, it then must be further tested in human clinical trials. Which of the following best explains why clinical trials are necessary?
Mice and humans have only 80% genetic similarity.
Which ancestor of the modern-day horse is also the closest common ancestor to Parahippus?
Miohippus
Which statement about evolution by natural selection is false?
Natural selection is a random change in allele frequencies over generations.
The fossil record indicates that the earliest known ancestor of horses has four toes. Modern horses have only one. Which of the following best explains why this occurred?
Offspring with genetic mutations resulting in fewer toes were more likely to survive and reproduce.
Which statement expresses the only way to prevent the evolution of new antibiotic-resistant bacteria?
Stop using antibiotics entirely.
Which statement is false?
The 13 different species of finches flew to the Galápagos Islands and separated themselves in response to different food environments.
Which of the following must be true if a population is undergoing evolution? Select the TWO answers that are correct.
The allele frequency of the population is changing over time. The gene pool is changing over the course of generations.
Chimpanzees exhibit 99% genetic similarity to humans. Cows share approximately 80% of their DNA sequence with humans. Scientists can predict the relative age of a common ancestor using DNA sequences. Which of the following statements regarding molecular clocks is true?
The common ancestor of chimpanzees and humans lived more recently than the common ancestor of cows, chimpanzees, and humans.
Which of the following is an example of nonadaptive evolution? Select the TWO answers that are correct.
The gene pool of a drastically reduced population of northern elephant seals is vulnerable to chance events. A mutation causes an increase in the incidence of antibiotic sensitivity in a population of Staphylococcus aureus.
Which statement is NOT a reason why homologous structures may look very different when comparing two different species?
The homologous structures may have arisen independently in the two species that are closely related.
Select the statement that describes how an organism's fitness level and environment relate to one another.
The more suitable an environment is for an organism's phenotype, the higher the organism's fitness level.
Select the explanation for why a phenotype is selected for in the first environment but selected against in the second environment.
The phenotype leads to higher rates of survival and reproduction in the first environment but lower rates of both in the second environment.
Which scenario would represent a situation that reduces the effect of genetic drift?
The population is very large.
Isabella is studying two populations of butterflies that live on opposite sides of a large lake. According to the biological species concept, which of the following would indicate that these two populations represent two separate species? Select the TWO answers that are correct.
The population of butterflies north of the lake breed in early spring, whereas the population south of the lake breeds in late summer. For sperm transfer in mating, the clasping organs of the males in one population are not suitable for holding onto the abdomen of the females in the other population.
If you examine a natural population of bacteria, it is common to find some antibiotic-sensitive and some antibiotic-resistant strains, even if the population has never been exposed to any antibiotic. Which explanation could account for this situation?
The resistant strain developed as a mutation and had no negative effect on fitness.
If you examine the gene pool of a population that is evolving due to genetic drift, what do you predict will occur with the allele frequencies?
There is no way to tell how p or q will change.
Which statements are true for both genetic bottlenecks and the founder effect? Select the TWO answers that are correct.
They both happen by chance. They both result in a smaller gene pool.
In addition to the beak differences, which statement indicates that the different finch populations found throughout the Galápagos Islands have experienced speciation?
They can no longer interbreed.
Which feature did Tiktaalik possess that were not possessed by earlier vertebrates?
a flexible wrist
Which change in the evolutionary history of horses is documented by the fossil record?
a gradual decrease in the number of toes
Which scenario would be LEAST likely to result in a fossil?
a jellyfish that dies and slowly floats to the ocean floor
An organism's fitness depends on its _____.
ability to survive and reproduce
The development and spread of a new gene for antibiotic-resistance in a population of bacteria that are exposed to that antibiotic would mean that trait is a(n) _____.
adaptation
Evidence that the Earth was much older than originally thought reached Darwin in numerous ways. Which of the following helped influence Darwin to believe in an ancient Earth?
all of these
Which condition can lead to two populations becoming different species?
all of these
Which factor is going to affect how natural selection acts on a given group of organisms?
all of these
Which factor may prevent most people from developing more than minor skin blemishes when they have a staph infection?
all of these
Which of these influences allele frequencies in a population?
all of these
Which process has been shown to contribute to the evolution of antibiotic resistance in S. aureus?
all of these
Why is the evolution of antibiotic resistance in bacteria happening so quickly?
all of these
The proportion of alleles present in a gene pool is called the _____ and is an important tool in measuring evolutionary changes.
allele frequency
The collection of _____ in a population constitutes that population's gene pool.
alleles
What is an effect of gene flow?
an increase in the variety of alleles within the gene pool of a population
Why aren't human populations evolving to produce immune systems that are able to fight off MRSA and other "superbugs"?
because the rate of human evolution is much slower than bacterial evolution
An individual who carries staph but isn't sick is referred to as _____.
colonized
Fossils are generally going to be more useful for studying animals that lived in or near water (e.g., streams, lakes, oceans, etc.) because _____.
dead animals that fall into water are more likely to be in conditions that allow fossilization
The variation in shape and function of the forelimb in tetrapods is a result of _____.
different environments leading to the evolution of different types of limbs
Which of the following does NOT contain structures homologous to the human arm?
dragonfly wing
Darwin observed finches on the Galapagos and compared them to finches back home in England. Species of finch are distinguishable by the different size and shape of their beaks. This suggested to Darwin that _____.
finch beaks have changed over time to match the food source that they depend on
In the Galapagos Islands, which of the following would have prevented the evolution of the many different species of finches?
frequent migration of finches between the islands
The forelimb of a chicken and a primate contain many of the same bones arranged in the same order. This is an example of _____.
homology
What can we learn about vertebrate evolution from Tiktaalik that we did not know before?
how vertebrates evolved tetrapod limbs
The offspring produced between the mating of a tiger and a lion, a liger, which is unable to reproduce, is an example of which form of reproductive isolation?
hybrid infertility
Inbreeding can lead to a decrease in genetic diversity and _____.
inbreeding depression
The Tiktaalik fossil, which dates back 375 million years, is considered a transitional fossil because _____.
it displays features found on both aquatic and land-dwelling species.
Which sequence places Tiktaalik in the correct evolutionary order?
lobe-finned fish, Tiktaalik, tetrapods
If bacteria reproduce through asexual reproduction, how does genetic variation occur? Select TWO that apply.
mutations gene transfer
Some portions of DNA function as a kind of evolutionary clock when comparing two different species because _____.
mutations accumulate at a known rate
In the late Devonian era, the seas began to recede and the land became more fertile. These environmental changes resulted in the emergence of land-dwelling vertebrates. Some animals are better able to survive and reproduce under changing environmental conditions. This is an example of:
natural selection
What is the evolutionary process called that causes antibiotic-resistant bacteria to increase and antibiotic-sensitive bacteria to decrease in an environment where antibiotics are present?
natural selection
All of these statements are true regarding S. aureus EXCEPT:
nearly 1% of the U.S. population is colonized with S. aureus.
Which of these is NOT an example of adaptive evolution?
none
Although all organisms share the same four nucleotides, it is the _____ of these nucleotides that makes each species unique.
sequence
A transitional fossil should _____.
share some similarity with species that lived before it and some similarity with species that lived after it.
A bacterial cell with which modification might be resistant to antibiotics such as methicillin?
the ability to produce an enzyme that breaks down the antibiotic
Which of the following is an example of gene flow?
the carriage of seeds between two separate urban forests by wildlife such as squirrels and rats that travel back and forth between the two
In strains of bacteria that are not resistant to beta-lactams, which part(s) of the bacterial cells are disrupted by the antibiotic?
the cell walls
Which of the following could result in the founder effect?
the establishment of a small colony of nonhuman primates on an isolated island off the coast of Africa
When Darwin compared the giant armadillo and sloth fossils to the living animals in Argentina, he found that _____.
the giant sloth and armadillo fossils bore a striking resemblance to the much smaller sloths and armadillos indigenous to the area
Natural selection is the idea that _____.
the natural environment selects for favorable traits and those favorable traits are passed on to the next generation of offspring
You examine a population and note that its allele frequencies for a particular gene are p = 0.55 and q = 0.45. If you came back and examined the population after several generations and found that the values for p and q had not changed, which statement would be false for this gene given this information alone?
the population is evolving
Which changes in a bacterial cell might reduce the effectiveness of beta-lactam antibiotics?
the presence of enzymes that are able to break down the antibiotic
Shubin and Daeschler specifically traveled to Ellesmere Island to hunt for fossils because _____.
the rocks on the island were of the right age to contain transitional vertebrate fossils.
Inheritance of acquired characteristics, called Lamarkianism, is based on the idea that _____.
traits that an organism acquires over the course of its lifetime can be passed on to offspring
What is the result of binary fission?
two daughter cells with genetic material identical to that of the parent cell
