AP Biology Semester 2 Midterm

Five new species of bacteria were discovered in Antarctic ice core samples. The nucleotide (base) sequences of rRNA subunits were determined for the new species. The table below shows the number of nucleotide differences between the species. Which of the following phylogenetic trees is most consistent with the data? A: 3, 4, 2, 1, 5 B: 2, 5, 1, 3, 4 C: 5, 3, 4, 1, 2 D: 4, 3, 5, 1, 2

A: 3, 4, 2, 1, 5

Students analyzed several photosynthetic eukaryotic organisms in the laboratory to determine their phylogenetic relationships. The organisms were Spirogyra (a green alga), a moss, a spruce tree, and an apple tree. Table 1 compares several characteristics in the organisms (+ indicates the trait is present, − indicates the trait is absent). Which of the following rows of data listed in table 1 best supports the possibility of a common ancestor for the organisms listed there? A: Cell wall composed of cellulose B: Seeds enclosed in fruit C: Vascular tissue D: Flagellated sperm cells

A: Cell wall composed of cellulose

Researchers were modeling the effects of repeated cycles of isolation with occasional interbreeding among five hypothetical fish species (species A, B, C, D, and E) found in two separate lakes (lakes I and II) that are occasionally joined by flooding, as shown in Figure 1. The research team indicated that species A would be considered to be the single common ancestor of species B, C, D, and E. Which of the following data could best support the claim that species B arose from a speciation event in Lake I? A: DNA analysis shows fewer differences between species A and species B in Lake I than between species B and the populations in Lake II. B: Individuals of species A from Lake I can mate and produce viable offspring with individuals of species A from Lake II. C: All of the fish species occupy the same niches in their respective lakes. D: Species A and species B have similar body shapes due to convergent evolution in their habitats.

A: DNA analysis shows fewer differences between species A and species B in Lake I than between species B and the populations in Lake II.

Which of the following is most likely to create genetic variation in a population? A: DNA polymerase errors during replication B: Misincorporation of amino acids by tRNA during translation C: Helicase failure to unwind DNA during DNA replication D: RNA polymerase errors during transcription

A: DNA polymerase errors during replication

The table below describes the action of two genes involved in the regulation of nervous system development in the nematode C. elegans. Which of the following claims is best supported by the data? A: Gene A promotes neuron development; gene B promotes programmed cell death in neuronal precursors. B: Gene A promotes programmed cell death in neuronal precursors; gene B promotes neuron development. C: Gene B must be active before gene A can function. D: Gene B must be inactive before gene A can function.

A: Gene A promotes neuron development; gene B promotes programmed cell death in neuronal precursors.

Which of the following statements best explains the structure and importance of plasmids to prokaryotes? A: Plasmids are circular, double-stranded DNA molecules that provide genes that may aid in survival of the prokaryotic cell. B: Plasmids are double-stranded RNA molecules that are transmitted by conjugation that enable other prokaryotic cells to acquire useful genes. C: Plasmids are circular, single-stranded RNA molecules that transfer information from the prokaryotic chromosome to the ribosomes during protein synthesis. D: Plasmids are single-stranded DNA molecules, which are replicated from the prokaryotic chromosome, that prevent viral reproduction within the prokaryotic cell.

A: Plasmids are circular, double-stranded DNA molecules that provide genes that may aid in survival of the prokaryotic cell.

_______ is the enzyme found in retroviruses that produce DNA from an RNA template. A: Reverse transcriptase B: DNA polymerase C: RNA polymerase D: Restriction enzyme E: DNA ligase

A: Reverse Transcriptase

In a small group of people living in a remote area, there is a high incidence of "blue skin", a condition that results from a variation in the structure of hemoglobin. All of the "blue-skinned" residents can trace their ancestry to one couple, who were among the original settlers of this region. The unusually high frequency of "blue skin" in the area is an example of A: genetic drift B: sexual selection C: heterozygote advantage D: natural selection E: mutation

A: genetic drift

Cell differentiation is a crucial stage of development in multicellular organisms. During differentiation, cells change their form and function as some genes are turned permanently on or off. One of the key ways that gene expression is regulated is through modification and regulation of chromatin. During normal embryonic development, DNA that will be inactivated for the lifetime of the cell is ______. A: methylated B: condensed to a Barr body C: acetylated D: discarded

A: methylated

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. Each beetle had been marked with a small spot of red paint on the underside of its abdomen before it was released. One week after the beetles had been released, any marked beetles that could be found were recaptured. The results are presented in the table below. It is assumed that differences in the numbers of beetles recaptured are directly related to differences in survival rates. Which of the following can be inferred from the data in the table? A: Insectivorous birds prefer to eat light-tan beetles rather than dark-brown beetles. B: Insectivorous birds are predators of this species of ground beetle. C: Ground beetles have higher rates of survival in habitats with loam soil. D: Ground beetles do not emigrate from the habitat in which they live. E: The reproductive success of beetles in habitats with sandy soils is greater than that of beetles in habitats with loam soils.

B: Insectivorous birds are predators of this species of ground beetle.

Tay-Sachs disease is a rare inherited disorder caused by an autosomal recessive allele of the HEXA gene. Affected individuals exhibit severe neurological symptoms and do not survive to reproductive age. Individuals who inherit one copy of the allele (Tay-Sachs carriers) typically show no symptoms of the disorder. The frequencies of Tay-Sachs carriers in the general population of North America and in three different subpopulations are presented in the table. Which of the following is an ethical question about Tay-Sachs disease that cannot be answered using scientific methods? A: Could the frequency of Tay-Sachs carriers in subpopulation I be a consequence of a genetic bottleneck? B: Should genetic testing be required before individuals in subpopulation III are advised to not have children? C: Would a difference in the HEXA alleles in subpopulations I and II affect the severity of the neurological symptoms? D: Should a statistical test be used to evaluate whether the general population is in Hardy-Weinberg equilibrium?

B: Should genetic testing be required before individuals in subpopulation III are advised to not have children?

Diapause is the interruption of an organism's life cycle in response to the environmental cues. The soil nematode Caenorhabditis elegans is capable of entering entering adult reproductive diapause (ARD) when food is scarce. In C. elegans, individuals normally become reproductively mature 2 days after hatching and remain fertile for 18 days. They reproduce either by self-fertilization or by mating with another individual. In an investigation, researchers examined the survival and reproductive success of female C. elegans who were without food for 0-30 days. Groups of C. elegans were held in ARD for different numbers of days before reintroduction of food. Average brood sizes (average number of offspring per adult) were determined following either self fertilization or mating with a well-fed males. The results are shown in Figure 1. In a second experiment, individuals were held in ARD without food for 0-30 days and monitored for average survival times following reintroduction of food (Figure 2). Based on the experimental results, which of the following is the best evolutionary explanation for the occurrence of ARD in C. elegans? A: Acquiring the genes for ARD gives individuals a selective advantage because they produce more offspring than do individuals who cannot enter ARD. B: The ability to enter ARD provides a strong selective advantage because reproduction can occur despite periods of food scarcity. C: Individuals who can enter ARD are selected for in the population because they live longer than do individuals who cannot enter ARD. D: Individuals who can enter ARD have high fitness because they can reproduce even when food is scarce.

B: The ability to enter ARD provides a strong selective advantage because reproduction can occur despite periods of food scarcity.

Figure 1 represents part of a process essential to gene expression. Figure 1. Model of process involved in gene expression. Which of the following best explains what strand X represents? A: The pre‑mRNA, because it does not yet have a GTP cap B: The antisense strand, because it is serving as a template C: A complementary RNA sequence, because it contains thymine D: The coding strand in this process, because it is being read 3′ to 5′

B: The antisense strand, because it is serving as a template

Tay-Sachs disease is a rare inherited disorder caused by an autosomal recessive allele of the HEXA gene. Affected individuals exhibit severe neurological symptoms and do not survive to reproductive age. Individuals who inherit one copy of the allele (Tay-Sachs carriers) typically show no symptoms of the disorder. The frequencies of Tay-Sachs carriers in the general population of North America and in three different subpopulations are presented in the table. A researcher claims that Tay-Sachs carriers are protected against the infectious disease tuberculosis (TB). Which of the following observations about the annual incidence of tuberculosis in subpopulation II could best be used to support the researcher's claim? A: The incidence of TB in subpopulation II is roughly equal to the incidence of Tay-Sachs disease in the general population. B: The incidence of TB in subpopulation II is lower than the incidence of TB in the general population. C: The incidence of TB in subpopulation II is greater than the incidence of TB in the general population. D: The incidence of TB in subpopulation II is roughly equal to the incidence of TB in the general population.

B: The incidence of TB in subpopulation II is lower than the incidence of TB in the general population.

Two groups of students attempted to re-create the primitive atmospheric conditions of early Earth using the apparatus represented below. Each group ran the experiment with different gas mixtures in the apparatus. Which of the following statements best justifies the claim that the conditions in at least one of the experiments could generate the molecular building blocks essential for life? A: The sulfur dioxide (SO2) gas in experiment 2 could donate the excited electrons required to drive the process of photosynthesis. B: The nitrogen (N2) gas and ammonia (NH3) gas in experiment 1 could provide the elemental nitrogen required for the formation of amino acids. C: The carbon dioxide (CO2) gas and water (H2O) vapor in experiment 1 could react spontaneously to produce the phospholipids required by the first life-forms. D: The methane (CH4) gas in experiment 2 could act as the electron acceptor required to complete the process of cellular respiration

B: The nitrogen (N2) gas and ammonia (NH3) gas in experiment 1 could provide the elemental nitrogen required for the formation of amino acids.

The regulatory sequences of the operon controlling arabinose metabolism (ara operon) were studied to determine whether bacteria can respond to changes in nutrient availability. It is predicted that if those regulatory sequences are functioning properly, the bacteria will produce the enzymes involved in arabinose metabolism (structural genes B, A, and D) in the presence of arabinose. If a gene that encodes a green fluorescent protein (GFP) is substituted for the structural genes of the operon, activation of the regulatory sequences can be assayed by GFP expression. A culture of E. coli cells underwent a transformation procedure with a plasmid containing the regulatory sequences of the ara operon directly upstream of the gene encoding the GFP. The plasmid also confers ampicillin resistance to bacteria. Samples were then plated on different types of culture media. (Note: The GFP fluoresces only under UV light, not under white light.) The table below shows the results. Which of the following can best be used to justify why the GFP is expressed by E. coli cells after transformation with the plasmid? A: The combination of ampicillin and arabinose in the nutrient agar inhibited the expression of certain gene products, resulting in the increased expression of the GFP. B: The presence of arabinose in the nutrient agar activated the expression of the genes located downstream of the ara operon regulatory sequences. C: The nutrient agar without arabinose but with ampicillin activated the expression of the genes located downstream of the ara operon regulatory sequences. D: Both arabinose and ampicillin were required in the nutrient agar to activate the expression of genes located downstream of the ara operon regulatory sequences.

B: The presence of arabinose in the nutrient agar activated the expression of the genes located downstream of the ara operon regulatory sequences.

A scientist is using an ampicillin-sensitive strain of bacteria that cannot use lactose because it has a nonfunctional gene in the lac operon. She has two plasmids. One contains a functional copy of the affected gene of the lac operon, and the other contains the gene for ampicillin resistance. Using restrictions enzymes and DNA ligase, she forms a recombinant plasmid containing both genes. She then adds a high concentration of the plasmid to a tube of the bacteria in a medium for bacterial growth that contains glucose as the only energy source. This tube (+) and a control tube (-) with similar bacteria but no plasmid are both incubated under the appropriate conditions for growth and plasmid uptake. The scientist then spreads a sample of each bacterial culture (+ and -) on each of the three types of plates indicated below. If the scientist had forgotten to use DNA ligase during the preparation of the recombinant plasmid, bacterial growth would most likely have occurred on which of the following? A: 1, 2, and 3 only B: 4 and 5 only C: 1 and 4 only D: 1 and 2 only E: 4, 5, and 6 only

C: 1 and 4 only

A moth's color is controlled by two alleles, G and g, at a single locus. G (gray) is dominant to g (white). A large population of moths was studied, and the frequency of the G allele in the population over time was documented, as shown in the figure below. In 1980 a random sample of 2,000 pupae was collected and moths were allowed to emerge. Assuming that the population was in Hardy-Weinberg equilibrium for the G locus, what percentage of moths in the natural population was white in 1962 ? A: 8% B: 64% C: 4% D: 20% E: 2%

C: 4%

Which evolution ancestor on this cladogram is the most recent in evolutionary time? A: 4 B: 7 C: 4, 5, 6, and 7 are equally recent D: 1

C: 4, 5, 6, and 7 are equally recent

The brown anole (Anolis sagrei) is a species of lizard native to Cuba that has been introduced into the southeastern United States. The range of brown anoles in the United States has been expanding, and they are now competing with native green anoles (Anolis carolinensis). Some of the characteristics of the green and brown anoles are shown in Table 1. Which of the following is the outgroup in the cladogram shown in Figure 1? A: A. gundlachi B: A. evermanni C: A. carolinensis D: A. stratulus

C: A. carolinensis

At the end of each replication bubble is a replication fork. This is the Y shaped region is A: where helicase is untwisting the double helix. B: where topoisomerase is fixing DNA overwinding ahead of replication by breaking, turning, and rejoining DNA strands. C: All of these are correct. D: where new DNA strands are elongating.

C: All of these are correct.

In gel electrophoresis, DNA runs from the top (-) of the gel toward the bottom (+). Why? A: DNA is heavier than the gel, so gravity pulls it toward the bottom B: If it didn't, we would not get a characteristic ladder banding pattern. C: DNA has an overall negative charge, so it moves toward the positive electrode in an electric field. D: DNA is not visible when it is running, so we actually don't know which direction it runs.

C: DNA has an overall negative charge, so it moves toward the positive electrode in an electric field.

Stickleback fish are found in both marine and freshwater habitats. The marine fish have no scales but have hardened, armorlike plates along their sides. The plates are thought to protect sticklebacks from certain predators. In the late 1980s, sticklebacks from a marine population colonized Loberg Lake, a freshwater lake in Alaska. Starting in 1990, researchers sampled fish from the lake every four years and recorded the armor-plate phenotypes of the male sticklebacks in each sample. The armor-plate phenotypes were categorized as either complete (plates extending from head to tail), partial (plates extending from head to abdomen), or low (a few plates near the head only). The results are shown in the table below. Which of the following best explains the changes in the phenotype frequencies of the stickleback population in Loberg Lake? A: Sticklebacks with the partial armor-plate phenotype have the highest rate of reproduction and survival. B: The population of sticklebacks in Loberg Lake is subject to genetic drift. C: Predation in the marine environment is different from predation in Loberg Lake. D: Marine predators and sticklebacks both colonized Loberg Lake.

C: Predation in the marine environment is different from predation in Loberg Lake.

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? A: The commercial banana strains should be exposed to X-rays to encourage random mutations that will then be passed to offspring, producing resistance to pathogenic organisms. B: The Cavendish banana plants should be exposed to pathogenic organisms under controlled conditions, so the plants can be encouraged to mutate and develop resistance to the pathogens C: 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. D: Growing the Cavendish strain under different conditions will allow natural selection to produce the variation needed to resist infection by pathogenic organisms.

C: 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

Female European corn borer moths (Ostrinia nubilalis) produce the sex pheromone 11−tetradecenyl acetate (11−TDA), which attracts males of their species. 11−TDA can be produced in two forms, E and Z, each with a different three-dimensional shape. Researchers have discovered two different strains of the European corn borer moth living in the same area. Females of the E strain produce primarily the E form of 11−TDA and females of the Z strain produce primarily the Z form of 11−TDA. Males of both strains are more attracted to the form of 11−TDA produced by the females of the same strain. Which of the following best predicts a long-term effect of the differences between the E and Z strains? A: Since the E and Z strains are both part of the same species, they will produce fertile offspring, leading to a single strain that produces both forms of 11−TDA. B: The difference between the forms of the sex pheromone 11−TDA produced by E and Z strains will act as a postzygotic reproductive barrier, leading to allopatric speciation. C: The difference between the forms of the sex pheromone 11−TDA produced by E and Z strains will act as a prezygotic reproductive barrier leading to sympatric speciation. D: Since the E and Z strains are found in the same geographic area, they will hybridize, leading to a single strain that produces the dominant form of 11−TDA.

C: The difference between the forms of the sex pheromone 11−TDA produced by E and Z strains will act as a prezygotic reproductive barrier leading to sympatric speciation.

Antigens are foreign proteins that invade the systems of organisms. Vaccines function by stimulating an organism's immune system to develop antibodies against a particular antigen. Developing a vaccine involves producing an antigen that can be introduced into the organism being vaccinated and which will trigger an immune response without causing the disease associated with the antigen. Certain strains of bacteria can be used to produce antigens used in vaccines. Which of the following best explains how bacteria can be genetically engineered to produce a desired antigen? A: The mRNA of the antigen has to be translated in order for the protein to be inserted into the bacteria. B: The DNA of the antigen has to be transcribed in order for the mRNA produced to be inserted into the bacteria. C: The gene coding for the antigen can be inserted into plasmids that can be used to transform the bacteria. D: The bacteria need to be exposed to the antigen so they can produce the antibodies.

C: The gene coding for the antigen can be inserted into plasmids that can be used to transform the bacteria.

Which of the following statements best explains how a condition of Hardy-Weinberg equilibrium results in a population that exhibits stable allele frequencies (i.e., a nonevolving population)? A: Random mating prevents gene flow from changing allele frequencies. B: In the absence of selection, allele frequencies in a population will not change. C: Without migration or mutation, new alleles cannot be introduced to the population. D: Large populations are not subject to natural selection.

C: Without migration or mutation, new alleles cannot be introduced to the population.

Competition for food would probably be most severe between two A: unrelated species in the same community occupying different niches B: unrelated species in different communities C: closely related species in similar niches D: ecological equivalents in different niches E: closely related species in different niches

C: closely related species in similar niches

Remnants of a pelvic girdle and hind limb bones can still be found in the skeleton of a modern snake. Darwin explains that these organs have become vestigial because A: natural selection favors maintaining these structures in a diminished form, just in case they ever become an advantageous variant. B: natural selection does not favor the preservation of body parts that do not enhance reproductive success. C: natural selection favors individuals who do not waste energy growing unnecessary appendages. D: artificial selection by humans has caused unattractive features to become diminished in species.

C: natural selection favors individuals who do not waste energy growing unnecessary appendages.

The students are sampling a site in search of fossils from the Devonian period. Based on the chart, which of the following would be the most reasonable plan for the students to follow? A: Using relative dating techniques to determine the geological ages of the fossils found so they can calculate the rate of speciation of early organisms B: Searching horizontal rock layers in any class of rock and trying to find those that contain the greatest number of fossils C: Looking in sedimentary layers next to bodies of water in order to find marine fossils of bivalves and trilobites D: Collecting fossils from rock layers deposited prior to the Permian period that contain some early vertebrate bones

D: Collecting fossils from rock layers deposited prior to the Permian period that contain some early vertebrate bones

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? A: Sequencing DNA isolated from fossils of lobe-finned fishes to determine the size of the genome B: Measuring the proportion of radioisotopes found in fossils of early tetrapods C: Determining the number of fins found on lobe-finned fishes from different geographical locations D: Comparing the arrangements of bones in the fins of lobe-finned fishes and limbs of the earliest tetrapods

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

Temporal isolation is a reproductive barrier that refers to A: morphological differences in the sex organs between different species which physically prevent them from interbreeding. B: physical separation of species by geographical barriers which prevent them from interbreeding. C: reduced viability of hybrid offspring, which causes hybrid offspring to die before reproductive maturity. D: timing isolation that prevents species from interbreeding due to time-of-day or seasonal mating behaviors.

D: timing isolation that prevents species from interbreeding due to time-of-day or seasonal mating behaviors.

_______ is the enzyme used to position nucleotides during DNA replication. A: Reverse transcriptase B: Restriction enzyme C: RNA polymerase D: DNA ligase E: DNA polymerase

E: DNA polymerase

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 A: parallel evolution B: allopatric speciation C: phyletic gradualism D: sympatric speciation E: punctuated equilibrium

E: punctuated equilibrium