ap bio un7

The cladogram shown below depicts an accepted model of the evolutionary relationships among selected species. The amino acid at position 104 in the beta-hemoglobin protein for each of these four organisms is listed below. The validity of the cladogram is best supported by molecular evidence for which of the following changes in the amino acid composition of the beta-hemoglobin protein during the evolution of these species?

Arginine to leucine at position X on the cladogram.

Data regarding the presence or absence of five derived traits in several different species are shown in the table below. Which of the following cladograms provides the simplest and most accurate representation of the data in the table?

the first cladogram option.

The TAS2R38 gene encodes a receptor protein that influences the ability to taste bitterness. The gene has two alleles, a dominant, wild-type allele that enables an individual taster to taste bitterness and a recessive, mutant allele that interferes with the ability of an individual nontaster to taste bitterness. Three single nucleotide mutations in the coding region of the TAS2R38 gene are associated with the nontaster allele. The nucleotides present at the three positions are shown in the table below. A cladogram representing the evolutionary relatedness of selected primates is shown below. In a sample of 2,400 people, 1,482 were found to have the dominant taster phenotype. Assuming that the population is in Hardy-Weinberg equilibrium, approximately how many individuals in the sample are expected to be heterozygous for TAS2R38?

1,133.

The TAS2R38 gene encodes a receptor protein that influences the ability to taste bitterness. The gene has two alleles, a dominant, wild-type allele that enables an individual taster to taste bitterness and a recessive, mutant allele that interferes with the ability of an individual nontaster to taste bitterness. Three single nucleotide mutations in the coding region of the TAS2R38 gene are associated with the nontaster allele. The nucleotides present at the three positions are shown in the table below. A cladogram representing the evolutionary relatedness of selected primates is shown below. Which of the following scientific questions will best help researchers determine when the nontaster allele arose in the evolutionary history of the selected primates?

Does the nontaster allele exist in any nonhuman primate populations?

There are autotrophic and heterotrophic organisms found in Bacteria, Archaea, and Eukarya.

There are autotrophic and heterotrophic organisms found in Bacteria, Archaea, and Eukarya.

Researchers studying the evolutionary relationships of three species of snails collected the data shown in Table 1. Table 1. Comparison of selected characteristics of three snail species … Which of the following data sets is most likely to provide reliable information about the evolutionary relationships among these three snail species?

Trophic level and DNA analysis.

A scientist is attempting to provide support for the hypothesis that RNA was the first genetic material. Which of the following would be a workable alternate hypothesis?

RNA can be observed to self-replicate without the assistance of proteins, while DNA always requires protein-based enzymes to replicate.

Many species of corals are threatened by the increasing temperatures and decreasing pH of ocean waters. One species, Stylophora pistillata, has been found to thrive in water that is warmer and has a lower pH than the water that corals typically thrive in. Additionally, researchers have found that the tolerance for the new water conditions is heritable. Which of the following statements best explains the changes seen in S. pistillata in response to the changing water conditions?

The corals adaptation is an example of natural selection because the tolerance is in response to a changing environment and has a genetic basis.

A group of researchers claim that chance events play an important role in the evolution of populations. To test their claim, they monitored 12 populations of E. coli for 10,000 generations under the same environmental conditions. They found that although all 12 populations were exposed to the same environmental pressures, each population had differentiated from one another genetically after 10,000 generations. Which of the following statements includes a reasonable refinement that researchers could use in repeating the experiment?

Start each population with genetically identical bacterial cells from a single culture to make sure that the initial genetic variation in all of the populations was exactly the same.

The figure shows a phylogenetic tree of various members of the order Proboscidea, which includes modern elephants. Which of the following claims is best supported by the information in the figure?

The common ancestor of the African elephant and the mastodon is the Palaeomastodon.

Evolutionary fitness is measured by

reproductive success.

Catalase is a protein enzyme that catalyzes the breakdown of hydrogen peroxide H2O2 into water and oxygen gas in the cells of many living organisms. Students used an online database, which used the structure of catalase from different species, to generate the phylogenetic tree shown in Figure 1. Which of the following student claims is best supported by the data provided?

Cattle and sheep are separated by only one node, and they are separated from the other organisms by more than one node.

All of the following are examples of prezygotic genetic isolating mechanisms EXCEPT

The progeny of a cross between two different lizard species fail to develop properly.

Scientists studying the evolution of bears analyzed the phylogenetic relationship among several extant bear species using 27 mitochondrial DNA mtDNA genomes. In addition to the five extant bear species, three genomes from an extinct species of cave bear were examined. The scientists constructed the phylogenetic tree Figure 1. Which of the following statements best explains the characteristics of two species that are on the same branch of the phylogenetic tree in Figure 1?

Their mtDNA genomes share more similarities with each other than with the mtDNA genomes of other species on the tree.

Geologic events such as mountain building can directly affect biodiversity. The SinoHimalayan fern, Lepisorus clathratus is widely distributed on the QinghaiTibetan plateau. If geologic events lead to a series of new mountain ranges that divide the plateau into several discrete valleys, which of the following best describes how the L. clathratus population would be affected?

Geographic isolation will create separate gene pools, leading to speciation over time.

Excess intracellular iron is toxic to cells iron-induced toxicity. Ferritin is an intracellular iron storage protein that binds excess iron. The presence of ferritin can protect cells from iron-induced toxicity. In an experiment to investigate the effects of dietary iron intake on ferritin synthesis, rats were given food containing different amounts of iron. Subsequently, the levels of ferritin protein in the liver were measured. Based on the data in Figure 1, the concentration of iron in the control diet used in the investigation is most likely within which of the following ranges?

3540 mgkg.

Excess intracellular iron is toxic to cells iron-induced toxicity. Ferritin is an intracellular iron storage protein that binds excess iron. The presence of ferritin can protect cells from iron-induced toxicity. In an experiment to investigate the effects of dietary iron intake on ferritin synthesis, rats were given food containing different amounts of iron. Subsequently, the levels of ferritin protein in the liver were measured. Based on the data in Figure 1, which of the following conclusions about dietary iron and ferritin synthesis is best supported by the data?

Maximum activation of ferritin synthesis occurs at dietary iron concentrations of 75 mgkg or greater.

Excess intracellular iron is toxic to cells iron-induced toxicity. Ferritin is an intracellular iron storage protein that binds excess iron. The presence of ferritin can protect cells from iron-induced toxicity. In an experiment to investigate the effects of dietary iron intake on ferritin synthesis, rats were given food containing different amounts of iron. Subsequently, the levels of ferritin protein in the liver were measured. After a search of nucleotide sequence databases, researchers identified an IRE in the 5 untranslated region of a gene encoding aconitase, an enzyme involved in the Krebs cycle. Which of the following pieces of experimental evidence best supports the claim that the synthesis of aconitase is controlled by a mechanism similar to ferritin regulation?

The relative amount of aconitase protein increases in the presence of high levels of iron.

The appearance of a fertile, polyploid individual within a population of diploid organisms is a possible source of a new species. If this individual is capable of reproducing to form a new population, scientists would consider this to be an example of

sympatric speciation.

Scientists investigated the role that beak depth plays in the ability of one species of seed-eating finch to reproduce. The scientists calculated the average beak depth of finches in mating pairs and then observed whether or not the pairs produced at least one offspring that survived to the next season. Based on the data in Figure 1, which of the following best describes the concept illustrated?

Parental pairs with a specific beak depth had the highest reproductive fitness.

Scientists are studying several populations of finches on neighboring islands in the South Pacific. Previous genetic analysis has shown that a single gene controls tail-feather length in the finch populations and that the allele for long tail feathers is dominant to the allele for short tail feathers. On two separate islands, the scientists recorded the number of finches with long tail feathers and the number of finches with short tail feathers. If the two finch populations are each in Hardy-Weinberg equilibrium and are isolated from each other, then which of the following graphs correctly displays the relative genotype frequencies?

the third graph option.

Researchers examined the ability of cultures of the bacterium Pseudomonas aeruginosa to adapt to the antibiotics ceftazidime and avibactam when they are administered together. All of the antibiotic-resistant mutants were missing three genes. It is known that one of these three genes makes wild-type P. aeruginosa susceptible to the two antibiotics. However, the researchers do not know which gene it is. Which of the following experiments would specifically determine which gene is responsible for ceftazidime-avibactam sensitivity in P. aeruginosa?

Perform gene knockout targeted mutation of either, or, or the gene on separate cultures of the wild-type P. aeruginosa. For each individual mutant, determine whether or not ceftazidime-avibactam resistance has occurred.

Cods and icefish are the only orders of fish that include species that produce antifreeze proteins in their blood. Based on the cladogram in Figure 1, which of the following scenarios describes the most likely evolutionary history of antifreeze protein synthesis in fish?

Antifreeze proteins arose twice, once in the cod lineage and once in the icefish lineage.

In a certain flock of sheep, 4 percent of the population has black wool and 96 percent has white wool. Assume that the population is in Hardy-Weinberg equilibrium. What percentage of the population is homozygous for white wool?

64.

The food web above represents feeding relationships in a biological community near a deep-sea hydrothermal vent. Hydrothermal vents are geysers on the seafloor that gush super-heated, mineral-rich water. The seawater surrounding hydrothermal vents typically contains carbon dioxide CO2, molecular hydrogen H2, hydrogen sulfide H2S, and methane CH4. Sunlight, however, fails to reach the seafloor where deep-sea hydrothermal vents are located. Researchers are investigating the evolutionary relationships among organisms found near deep-sea hydrothermal vents and similar organisms found closer to the ocean surface. Which of the following scientific questions is most relevant to the investigation?

What are the nucleotide sequences of ribosomal RNA genes that are found in the genomes of the different species?

Many scientists claim that the synthesis of the first organic molecules from inorganic precursors was possible because of the highly reducing atmosphere found on primitive Earth. Which of the following is an appropriate null hypothesis that could be used when investigating the claim?

The synthesis of organic molecules from inorganic molecules is possible under current atmospheric oxygen levels as well as those found on primitive Earth.

Figure 1. Effectiveness of Insecticides 1 and 2. Of the following, which is the best next step for the researchers to best determine the long-term effectiveness of these insecticides with regards to the development of resistance?

Continue treating the three insect populations with the same insecticides and determine whether their efficiency declines significantly after several generations.

The wing of a bat, the flipper of a whale, and the forelimb of a horse appear very different, yet detailed studies reveal the presence of the same basic bone pattern. These structures are examples of

homologous structures.

Figure 1. A hypothesized phylogenetic relationship among some members of the Hawaiian honeycreeper bird family. One hypothesized phylogenetic relationship among selected members of the Hawaiian honeycreeper bird family is shown in Figure 1. Based on the phylogenetic tree, birds in which of the following pairs share the most recent common ancestor?

L. caeruleirostris and H. virens.

A particular gene has two alleles, a dominant allele and a recessive allele. The frequency of allele is 0.55. If the population is in Hardy-Weinberg equilibrium with respect to the gene, then what is the expected frequency of genotype ?

0.495.

Dr. Robert Hazen has worked to develop a hypothesis that explains the origin of life on Earth. His work has focused on hydrothermal vents, which are cracks in the ocean floor. In order to provide evidence that these vents may be areas where life originated, which of the following states a null hypothesis Hazen might have used to begin his research?

Chemosynthetic organisms can best develop in the hydrothermal environment, manufacturing nutrients for other living things to feed on.

High blood cholesterol hypercholesterolemia, HC can lead to cardiovascular problems such as atherosclerosis and heart attack. Exercise and monitoring of diet can often control cholesterol levels however, in certain cases HC is inherited as an autosomal dominant disease caused by a mutation in a single gene. A man with high cholesterol levels is about to marry a woman whose total cholesterol levels are also higher than average. A physician has suggested they get tested for the allele. Which of the following is a valid ethical question concerning the test?

How important are the results of the test to the couples health, since they already know they have HC?

A group of people whose ancestors immigrated to North America 200 years ago have certain allele frequencies that differ significantly from those in surrounding populations in the United States. Which of the following is the most likely explanation for the difference in allele frequencies?

Reproductive isolation.

A scientist is studying the impact of mutagens on genetic variation in mice. In an experiment, the scientist creates two groups of twenty highly inbred mice… Which of the following is the most reasonable prediction about the results of the experiment?

The group given the mutagen will have greater variation in food digestion efficiency after several generations.

Based on the data in the table, which of the following lizard species are most closely related?

Species E and species D.

A scientist is studying a population of lizards with three different color phenotypes… To test the hypothesis that the population is at Hardy-Weinberg equilibrium, the scientist performed a chi-square test. Which of the following values is closest to the chi-square value the scientist calculated?

23.1.

Lobe-finned fishes were present in the oceans of the world approximately 400 million years ago. The first tetrapods vertebrates that had limbs and could move on land date to about 365 million years ago. One hypothesis states that early tetrapods evolved from lobe-finned fishes. Which of the following is the best plan for testing the hypothesis?

Comparing the arrangements of bones in the fins of lobe-finned fishes and limbs of the earliest tetrapods.

Gaucher disease type 1 GD1 is a recessive genetic disease that affects 1 in 900 individuals in a particular population. GD1 is caused by a mutation in the enzyme glucocerebrosidase. Assuming the population is in Hardy-Weinberg equilibrium, calculate the frequency of the wild-type nonmutant allele for the enzyme glucocerebrosidase.

0.967.

A researcher uses the protocol shown in Figure 1 to isolate a eukaryotic gene for the purpose of genetically engineering bacteria to synthesize the corresponding protein. Which of the following best predicts why the recombinant bacteria will fail to produce the eukaryotic protein?

Introns must be removed from eukaryotic DNA before the gene is inserted into the plasmid.

On a large volcanic island, researchers are studying a population of annual herbaceous plants. Which of the following observations best supports the prediction that speciation will occur within the existing plant population?

Lava has separated the population into two areas an upland forest and a lowland marsh.

Figure 1 shows some major structural changes between a typical prokaryotic cell, the first eukaryotic common ancestor, and the last eukaryotic common ancestor. Based on the information provided in the figure, which of the following best predicts how membrane-bound organelles provided unique evolutionary advantages to the last eukaryotic common ancestor?

Cells with mitochondria were able to utilize metabolic energy more efficiently.

Scientists are interested in determining the evolution of seven lizard species found on different islands of the Canary Island group. They isolated DNA from individuals of each species and sequenced the mitochondrial gene that encodes cytochrome. The numbers of genetic differences between species are shown in the table below.

species with the fewest genetic differences were the most closely related.

Two populations of a species of squirrel are geographically isolated from each other. Although they have the same population density, one population is significantly larger in number than the other. A new bacterial disease, which is easily spread and extremely virulent, affects both populations at the same time. Which of the following is the best prediction of how the new disease will affect the two populations?

The smaller population will be more affected than will the larger population, because the smaller population has less genetic variation than the larger population has.

Individuals of a particular species of ground beetle are either light tan or dark brown. Light-tan beetles are predominant in habitats with light-colored sandy soils, and dark-brown beetles are predominant in habitats with dark-colored loam soils. In an experiment designed to determine the survival rates of light-tan beetles and dark-brown beetles in different habitats, 500 light-tan beetles and 500 dark-brown beetles were released in each of four habitats. One week after the beetles had been released, any marked beetles that could be found were recaptured.

directional selection in matching habitats.

The fossil record indicates that in some cases reasonably well-defined species appear suddenly and remain unchanged for a long time before they become extinct. This phenomenon is referred to as

punctuated equilibrium.

Over many years of a breeding program, a zoo has an established population of foxes that is well adapted for living in captivity. A representative sample of wild foxes from the neighboring forest was used to start the zoo population. A study was conducted to compare the behavior of the zoo fox population with the wild fox population in the neighboring forest. The phenotypic variation in behavior between the two populations can best be described as resulting from

artificial selection.

Freshwater bony fish secrete large volumes of very dilute urine. Many marine bony fish secrete small volumes of concentrated urine. Which of the following best explains the differences in nitrogenous-waste excretion between freshwater and marine bony fish?

The differences arose during divergence, as fish from a common ancestor faced different selective pressures in environments of different osmolarity.

A scientist maintains a large population of the fruit fly Drosophila affinis in the laboratory. After 20 generations of allowing this population of about 1000 flies to mate randomly, 10 females and 10 males were isolated from the rest of the population. Both the larger population and the isolated population were maintained under identical conditions and allowed to mate randomly for another 20 generations. After the 20 generations, DNA sequencing was used to determine the genetic composition of each population.

The two populations will show significant genetic differences because the founder effect will result in significant losses in diversity in the smaller population.

Over several years, bacteria were isolated from members of a human population and tested for antibiotic resistance. The percent of bacterial isolates that were found to be antibiotic resistant is presented in the graph above for each year of the study. Which of the following conclusions is best supported by the information presented in the graph?

Natural selection over multiple generations is favoring antibiotic resistance in the population of bacteria.

A current challenge for doctors involves the bacterial strain Clostridioides difficile, which no longer responds to traditional antibiotic treatments. Which of the following best explains why this particular strain of bacteria is resistant to antibiotic treatment?

The bacteria have high genetic variability and high reproductive rates.

Commercial bananas are grown as a monoculture, with all banana plants cloned from one original banana plant. The commercial strains of bananas are seedless, so each new banana plant has to be manually planted from a cutting of an existing banana root. In the 1950s, the Gros Michel banana strain, the dominant export banana at that time, was destroyed by the fungus Fusarium oxysporum. A new Fusarium resistant variety, the Cavendish banana, was developed and is currently the banana strain grown for export. Recently, a Fusarium strain that successfully attacks the Cavendish strain has been documented. Which of the following best provides reasoning supporting a method that would help protect commercial banana crops from infection by pathogenic organisms such as Fusarium fungi?

The commercial banana strains should not be grown in monocultures, since many pathogenic organisms are able to evolve rapidly in response to a single selective pressure.