AP Biology Chapters 19 and 27 Easy Notecards
11) If a bacterium regenerates from an endospore that did not possess any of the plasmids that were contained in its original parent cell, the regenerated bacterium will probably also A) lack antibiotic-resistant genes. B) lack a cell wall. C) lack a chromosome. D) lack water in its cytoplasm. E) be unable to survive in its normal environment.
A
17) The difference between vertical and horizontal transmission of plant viruses is that A) vertical transmission is transmission of a virus from a parent plant to its progeny, and horizontal transmission is one plant spreading the virus to another plant. B) vertical transmission is the spread of viruses from upper leaves to lower leaves of the plant, and horizontal transmission is the spread of a virus among leaves at the same general level. C) vertical transmission is the spread of viruses from trees and tall plants to bushes and other smaller plants, and horizontal transmission is the spread of viruses among plants of similar size. D) vertical transmission is the transfer of DNA from one type of plant virus to another, and horizontal transmission is the exchange of DNA between two plant viruses of the same type. E) vertical transmission is the transfer of DNA from a plant of one species to a plant of a different species, and horizontal transmission is the spread of
A
31) Assuming that each of these possesses a cell wall, which prokaryotes should be expected to be most strongly resistant to plasmolysis in hypertonic environments? A) extreme halophiles B) extreme thermophiles C) methanogens D) cyanobacteria E) nitrogen-fixing bacteria that live in root nodules
A
13) Prokaryotes' essential genetic information is located in the A) nucleolus. B) nucleoid. C) nucleosome. D) plasmids. E) exospore.
B
13) What is the function of reverse transcriptase in retroviruses? A) It hydrolyzes the host cell's DNA. B) It uses viral RNA as a template for DNA synthesis. C) It converts host cell RNA into viral DNA. D) It translates viral RNA into proteins. E) It uses viral RNA as a template for making complementary RNA strands.
B
14) Which of the following can be effective in preventing the onset of viral infection in humans? A) taking vitamins B) getting vaccinated C) taking antibiotics D) applying antiseptics E) taking nucleoside analogs that inhibit transcription
B
35) In general, what is the primary ecological role of prokaryotes? A) parasitizing eukaryotes, thus causing diseases B) breaking down organic matter C) metabolizing materials in extreme environments D) adding methane to the atmosphere E) serving as primary producers in terrestrial environments
B
47) RNA viruses require their own supply of certain enzymes because A) host cells rapidly destroy the viruses. B) host cells lack enzymes that can replicate the viral genome. C) these enzymes translate viral mRNA into proteins. D) these enzymes penetrate host cell membranes. E) these enzymes cannot be made in host cells.
B
9) Why do RNA viruses appear to have higher rates of mutation? A) RNA nucleotides are more unstable than DNA nucleotides. B) Replication of their genomes does not involve proofreading. C) RNA viruses replicate faster. D) RNA viruses can incorporate a variety of nonstandard bases. E) RNA viruses are more sensitive to mutagens.
B
25) In the figure, at the arrow marked II, what enzyme(s) are being utilized? A) reverse transcriptase B) viral DNA polymerase C) host cell DNA polymerase D) host cell RNA polymerase E) host cell DNA and RNA polymerases
C
1) Viral genomes vary greatly in size and may include from four genes to several hundred genes. Which of the following viral features is most apt to correlate with the size of the genome? A) size of the viral capsomeres B) RNA versus DNA genome C) double- versus single-strand genomes D) size and shape of the capsid E) glycoproteins of the envelope
D
12) Although not present in all bacteria, this cell covering often enables cells that possess it to resist the defenses of host organisms, especially their phagocytic cells. A) endospore B) sex pilus C) cell wall D) capsule
D
75) Which of the following statements is not true? A) Archaea and bacteria have different membrane lipids. B) Both archaea and bacteria generally lack membrane-enclosed organelles. C) The cell walls of archaea lack peptidoglycan. D) Only bacteria have histones associated with DNA. E) Only some archaea use CO₂ to oxidize H₂, releasing methane.
D
76) Which of the following involves metabolic cooperation among prokaryotic cells? A) binary fission B) endospore formation C) endotoxin release D) biofilms E) photoautotrophy
D
10) Most molecular biologists think that viruses originated from fragments of cellular nucleic acid. Which of the following observations supports this theory? A) Viruses contain either DNA or RNA. B) Viruses are enclosed in protein capsids rather than plasma membranes. C) Viruses can reproduce only inside host cells. D) Viruses can infect both prokaryotic and eukaryotic cells. E) Viral genomes are usually similar to the genome of the host cell.
E
19) Which of the following is the best predictor of how much damage a virus causes? A) ability of the infected cell to undergo normal cell division B) ability of the infected cell to carry on translation C) whether the infected cell produces viral protein D) whether the viral mRNA can be transcribed E) how much toxin the virus produces
A
21) Hershey and Chase performed an elegant experiment that convinced most biologists that DNA, rather than protein, was the genetic material. This experiment subjected bacteria to the same gene transfer mechanism as occurs in A) transduction. B) transformation. C) conjugation. D) binary fission. E) endosymbiosis.
A
28) Which statement about the domain Archaea is true? A) Genetic prospecting has recently revealed the existence of many previously unknown archaean species. B) No archaeans can reduce CO₂ to methane. C) The genomes of archaeans are unique, containing no genes that originated within bacteria. D) No archaeans can inhabit solutions that are nearly 30% salt. E) No archaeans are adapted to waters with temperatures above the boiling point.
A
4) Most human-infecting viruses are maintained in the human population only. However, a zoonosis is a disease that is transmitted from other vertebrates to humans, at least sporadically, without requiring viral mutation. Which of the following is the best example of a zoonosis? A) rabies B) herpesvirus C) smallpox D) HIV E) hepatitis virus
A
5) Jams, jellies, preserves, honey, and other foodstuffs with high sugar content hardly ever become contaminated by bacteria, even when the food containers are left open at room temperature. This is because bacteria that encounter such an environment A) undergo death by plasmolysis. B) are unable to metabolize the glucose or fructose, and thus starve to death. C) experience lysis. D) are obligate anaerobes. E) are unable to swim through these thick and viscous materials.
A
51) The data were collected from the heterocysts of a nitrogen-fixing cyanobacterium inhabiting equatorial ponds. Study the following graph and choose the most likely explanation for the shape of the curve. A) Enough O₂ enters heterocysts during hours of peak photosynthesis to have a somewhat-inhibitory effect on nitrogen fixation. B) Light-dependent reaction rates must be highest between 1800 hours and 0600 hours. C) Atmospheric N₂ levels increase at night because plants are no longer metabolizi
A
52) Consider the thermoacidophile, Sulfolobus acidocaldarius. Which of the following graphs most accurately depicts the expected temperature and pH profiles of its enzymes? (Note: The horizontal axes of these graphs are double, with pH above and temperature below.) A. SEE IMAGE B. SEE IMAGE C. SEE IMAGE D. SEE IMAGE
A
74) Photoautotrophs use A) light as an energy source and CO₂ as a carbon source. B) light as an energy source and methane as a carbon source. C) N₂ as an energy source and CO₂ as a carbon source. D) CO₂ as both an energy source and a carbon source. E) H₂S as an energy source and CO₂ as a carbon source.
A
78) Plantlike photosynthesis that releases O₂ occurs in A) cyanobacteria. B) chlamydias. C) archaea. D) actinomycetes. E) chemoautotrophic bacteria.
A
9) Prokaryotic ribosomes differ from those present in eukaryotic cytosol. Because of this, which of the following is correct? A) Some antibiotics can block protein synthesis in bacteria without effects in the eukaryotic host. B) Eukaryotes did not evolve from prokaryotes. C) Translation can occur at the same time as transcription in eukaryotes but not in prokaryotes. D) Some antibiotics can block the synthesis of peptidoglycan in the walls of bacteria. E) Prokaryotes are able to use a much greater variety of molecules as food sources than can eukaryotes.
A
Figure 27.2 depicts changes to the amount of DNA present in a recipient cell that is engaged in conjugation with an Hfr cell. Hfr cell DNA begins entering the recipient cell at Time A. Assume that reciprocal crossing over occurs (in other words, a fragment of the recipient's chromosome is exchanged for a homologous fragment from the Hfr cell's DNA). Use Figure 27.2 to answer the following question. Figure 27.2 49) During which two times can the recipient accurately be described as "recombinant" due to the sequence of events port
A
Figure 27.2 depicts changes to the amount of DNA present in a recipient cell that is engaged in conjugation with an Hfr cell. Hfr cell DNA begins entering the recipient cell at Time A. Assume that reciprocal crossing over occurs (in other words, a fragment of the recipient's chromosome is exchanged for a homologous fragment from the Hfr cell's DNA). Use Figure 27.2 to answer the following question. Figure 27.2 50) Which question, arising from the results depicted in Figure 27.2, is most interesting from a genetic perspective, and has th
A
In 1971, David Baltimore described a scheme for classifying viruses based on how the virus produces mRNA. The table below shows the results of testing five viruses for nuclease specificity, the ability of the virus to act as an mRNA, and presence (+) or absence (-) of its own viral polymerase (SEE IMAGE) 36) Based on the above table, which virus meets the requirements for a bacteriophage? A) A B) B C) C D) D
A
The following table depicts characteristics of five prokaryotic species (A—E). Use the information in the table to answer the following question. 66) Gram-variable prokaryotes are, sometimes, those without any peptidoglycan. Which two species are most likely to be archaeans? A) species A and B B) species A and C C) species B and E D) species C and D E) species C and E
A
The following table depicts characteristics of five prokaryotic species (A—E). Use the information in the table to answer the following question. 70) Which two species might be expected to cooperate metabolically, perhaps forming a biofilm wherein one species surrounds cells of the other species? A) species A and B B) species A and C C) species B and E D) species C and D E) species C and E
A
You isolate an infectious substance that is capable of causing disease in plants, but you do not know whether the infectious agent is a bacterium, virus, viroid, or prion. You have four methods at your disposal that you can use to analyze the substance in order to determine the nature of the infectious agent. I. treating the substance with nucleases that destroy all nucleic acids and then determining whether it is still infectious II. filtering the substance to remove all elements smaller than what can be easily seen under a light microscope III. culturing the substance by itself on nutritive medium, away from any plant cells IV. treating the sample with proteases that digest all proteins and then determining whether it is still infectious 37) Which treatment could definitively determine whether or not the component is a viroid?
A
1) Mycoplasmas are bacteria that lack cell walls. On the basis of this structural feature, which statement concerning mycoplasmas should be true? A) They are gram-negative. B) They are subject to lysis in hypotonic conditions. C) They lack a cell membrane as well. D) They should contain less cellulose than do bacteria that possess cell walls. E) They possess typical prokaryotic flagella.
B
15) Which of the following describes plant virus infections? A) They can be controlled by the use of antibiotics. B) They are spread via the plasmodesmata. C) They have little effect on plant growth. D) They are seldom spread by insects. E) They can never be passed vertically.
B
16) In a hypothetical situation, the genes for sex pilus construction and for tetracycline resistance are located together on the same plasmid within a particular bacterium. If this bacterium readily performs conjugation involving a copy of this plasmid, then the result should be A) a bacterium that has undergone transduction. B) the rapid spread of tetracycline resistance to other bacteria in that habitat. C) the subsequent loss of tetracycline resistance from this bacterium. D) the production of endospores among the bacterium's progeny. E) the temporary possession by this bacterium of a completely diploid genome.
B
16) Which of the following represents a difference between viruses and viroids? A) Viruses infect many types of cells, whereas viroids infect only prokaryotic cells. B) Viruses have capsids composed of protein, whereas viroids have no capsids. C) Viruses contain introns, whereas viroids have only exons. D) Viruses always have genomes composed of DNA, whereas viroids always have genomes composed of RNA. E) Viruses cannot pass through plasmodesmata, whereas viroids can.
B
2) Though plants, fungi, and prokaryotes all have cell walls, we place them in different taxa. Which of these observations comes closest to explaining the basis for placing these organisms in different taxa, well before relevant data from molecular systematics became available? A) Some closely resemble animals, which lack cell walls. B) Their cell walls are composed of very different biochemicals. C) Some have cell walls only for support. D) Some have cell walls only for protection from herbivores. E) Some have cell walls only to control osmotic balance.
B
2) Viral envelopes can best be analyzed with which of the following techniques? A) transmission electron microscopy B) antibodies against specific proteins not found in the host membranes C) staining and visualization with the light microscope D) use of plaque assays for quantitative measurement of viral titer E) immunofluorescent tagging of capsid proteins
B
20) Antiviral drugs that have become useful are usually associated with which of the following properties? A) ability to remove all viruses from the infected host B) interference with viral replication C) prevention of the host from becoming infected D) removal of viral proteins E) removal of viral mRNAs
B
24) Match the numbered terms to the description that follows. Choose all appropriate terms. 1. autotroph 2. heterotroph 3. phototroph 4. chemotroph an organism that relies on photons to excite electrons within its membranes A) 1 only B) 3 only C) 1 and 3
B
27) A linear piece of viral DNA of 8 kb can be cut with either of two restriction enzymes (X or Y). These are subjected to electrophoresis and produce the following bands: (SEE IMAGE PART ONE) Cutting the same 8 kb piece with both enzymes together results in bands at 4.0, 2.5, 1.0, and 0.5. Of the possible arrangements of the sites given below, which one is most likely? A. SEE IMAGE B. SEE IMAGE C. SEE IMAGE
B
38) Foods can be preserved in many ways by slowing or preventing bacterial growth. Which of these methods should be least effective at inhibiting bacterial growth? A) Refrigeration: slows bacterial metabolism and growth. B) Closing previously opened containers: prevents more bacteria from entering, and excludes O₂. C) Pickling: creates a pH at which most bacterial enzymes cannot function. D) Canning in heavy sugar syrup: creates osmotic conditions that remove water from most bacterial cells. E) Irradiation: kills bacteria by mutating their DNA to such an extent that their DNA-repair enzymes are overwhelmed.
B
7) Which two structures play direct roles in permitting bacteria to adhere to each other, or to other surfaces? 1. capsules 2. endospores 3. fimbriae 4. plasmids 5. flagella A) 1 and 2 B) 1 and 3 C) 2 and 3
B
77) Bacteria perform each of the following ecological roles. Which role typically does not involve a symbiosis? A) skin commensalist B) decomposer C) aggregates with methane-consuming archaea D) gut mutualist E) pathogen
B
In 1971, David Baltimore described a scheme for classifying viruses based on how the virus produces mRNA. The table below shows the results of testing five viruses for nuclease specificity, the ability of the virus to act as an mRNA, and presence (+) or absence (-) of its own viral polymerase (SEE IMAGE) 34) Given Baltimore's scheme, a positive sense single-stranded RNA virus such as the polio virus would be most closely related to which of the following? A) T-series bacteriophages B) retroviruses that require a DN
B
Nitrogenase, the enzyme that catalyzes nitrogen fixation, is inhibited whenever free O₂ reaches a critical concentration. Consequently, nitrogen fixation cannot occur in cells wherein photosynthesis produces free O₂. Consider the colonial aquatic cyanobacterium, Anabaena, whose heterocytes are described as having "...a thickened cell wall that restricts entry of O₂ produced by neighboring cells. Intracellular connections allow heterocysts to transport fixed nitrogen to neighboring cells in exchange for carbohydrates." 62) Which two questions below arise from a careful reading of this quotation, and are most important for understanding how N₂ enters heterocysts, and how O₂ is kept out of heterocysts? 1. If carbohydrates can enter the heterocysts from neighboring cells via the "intracellular connections," how is it that O₂ doesn't also enter via this route? 2. If the cell walls of Anabaena's photosynthetic cells are permeable to O₂ and CO₂, are they also permeable to N₂?
B
Some viruses can be crystallized and their structures analyzed. One such virus is Desmodium, or yellow mottle virus, which infects beans. This is a member of the tymovirus group and has a single-stranded RNA genome of ~6,300 nucleotides. Its virion is 25—30 nm in diameter, and is made up of 180 copies of a single capsid protein that self-associate to form each capsomere, which has icosahedral symmetry with 20 facets. 31) In a cell-free system, what other components would you have to provide for this virus to express its genes? A) ribosomes, tRNAs and amino acids B) ribosomes, tRNAs, amino acids, and GTP C) RNA nucleotides and GTP D) RNA nucleotides, RNA polymerase, and GTP E) bean cell enzymes
B
The following table depicts characteristics of five prokaryotic species (A—E). Use the information in the table to answer the following question. 71) Which species is most likely to be found both in sewage treatment plants and in the guts of cattle? A) species A B) species B C) species C D) species D E) species E
B
The herpes viruses are very important enveloped DNA viruses that cause disease in all vertebrate species and in some invertebrates such as oysters. Some of the human ones are herpes simplex (HSV) I and II, causing facial and genital lesions, and the varicella-zoster (VSV), causing chicken pox and shingles. Each of these three actively infect nervous tissue. Primary infections are fairly mild, but the virus is not then cleared from the host; rather, viral genomes are maintained in cells in a latent phase. The virus can then reactivate, replicate again, and be infectious to others. 40) If scientists are trying to use what they know about HSV to devise a means of protecting other people from being infected, which of the following would have the best chance of lowering the number of new cases of infection? A) vaccination of all persons with preexisting cases B) interference with new viral replication in preexisting cases C) treatment of the HSV lesions to shorten the breakout D) medication that destroys surface HSV before it g
B
11) A researcher lyses a cell that contains nucleic acid molecules and capsomeres of tobacco mosaic virus (TMV). The cell contents are left in a covered test tube overnight. The next day this mixture is sprayed on tobacco plants. Which of the following would be expected to occur? A) The plants would develop some but not all of the symptoms of the TMV infection. B) The plants would develop symptoms typically produced by viroids. C) The plants would develop the typical symptoms of TMV infection. D) The plants would not show any disease symptoms. E) The plants would become infected, but the sap from these plants would be unable to infect other plants.
C
15) Chloramphenicol is an antibiotic that targets prokaryotic (70S) ribosomes, but not eukaryotic (80S) ribosomes. Which of these questions stems from this observation, plus an understanding of eukaryotic origins? A) Can chloramphenicol also be used to control human diseases that are caused by archaeans? B) Can chloramphenicol pass through the capsules possessed by many cyanobacteria? C) If chloramphenicol inhibits prokaryotic ribosomes, should it not also inhibit mitochondrial ribosomes? D) Why aren't prokaryotic ribosomes identical to eukaryotic ribosomes? E) How is translation affected in ribosomes that are targeted by chloramphenicol?
C
18) Which of these statements about prokaryotes is correct? A) Bacterial cells conjugate to mutually exchange genetic material. B) Their genetic material is confined within vesicles known as plasmids. C) They divide by binary fission, without mitosis or meiosis. D) The persistence of bacteria throughout evolutionary time is due to their genetic homogeneity (in other words, sameness). E) Genetic variation in bacteria is not known to occur, because of their asexual mode of reproduction.
C
25) Which of the following obtain energy by oxidizing inorganic substancesenergy that is used, in part, to fix CO₂? A) photoautotrophs B) photoheterotrophs C) chemoautotrophs D) chemoheterotrophs that perform decomposition E) parasitic chemoheterotrophs
C
3) Which statement about bacterial cell walls is false? A) Bacterial cell walls differ in molecular composition from plant cell walls. B) Cell walls prevent cells from bursting in hypotonic environments. C) Cell walls prevent cells from dying in hypertonic conditions. D) Bacterial cell walls are similar in function to the cell walls of many protists, fungi, and plants. E) Cell walls provide the cell with a degree of physical protection from the environment.
C
32) The thermoacidophile, Sulfolobus acidocaldarius, lacks peptidoglycan, but still possesses a cell wall. What is likely to be true of this species? 1. It is a bacterium. 2. It is an archaean. 3. The optimal pH of its enzymes will lie above pH 7. 4. The optimal pH of its enzymes will lie below pH 7. 5. It could inhabit certain hydrothermal springs. 6. It could inhabit alkaline hot springs. A) 1, 3, and 6 B) 2, 4, and 6 C) 2, 4, and 5 D) 1, 3, and 5 E) 1, 4, and 5
C
37) In a hypothetical situation, a bacterium lives on the surface of a leaf, where it obtains nutrition from the leaf's nonliving, waxy covering while inhibiting the growth of other microbes that are plant pathogens. If this bacterium gains access to the inside of a leaf, however, it causes a fatal disease in the plant. Once the plant dies, the bacterium and its offspring decompose the plant. What is the correct sequence of ecological roles played by the bacterium in the situation described here? Use only those that apply. 1. nutrient recycler 2. mutualist 3. commensal 4.parasite 5. primary producer A) 1, 3, 4 B) 2, 3, 4 C) 2, 4, 1
C
43) Which of the following characteristics, structures, or processes is common to both bacteria and viruses? A) metabolism B) ribosomes C) genetic material composed of nucleic acid D) cell division E) independent existence
C
45) To cause a human pandemic, the H5N1 avian flu virus would have to A) spread to primates such as chimpanzees. B) develop into a virus with a different host range. C) become capable of human-to-human transmission. D) arise independently in chickens in North and South America. E) become much more pathogenic.
C
6) In many ways, the regulation of the genes of a particular group of viruses will be similar to the regulation of the host genes. Therefore, which of the following would you expect of the genes of the bacteriophage? A) regulation via acetylation of histones B) positive control mechanisms rather than negative C) control of more than one gene in an operon D) reliance on transcription activators E) utilization of eukaryotic polymerases
C
8) The typical prokaryotic flagellum features A) an internal 9 + 2 pattern of microtubules. B) an external covering provided by the plasma membrane. C) a complex "motor" embedded in the cell wall and plasma membrane. D) a basal body that is similar in structure to the cell's centrioles. E) a membrane-enclosed organelle with motor proteins.
C
8) Which of the following statements describes the lysogenic cycle of lambda (λ) phage? A) After infection, the viral genes immediately turn the host cell into a lambda-producing factory, and the host cell then lyses. B) Most of the prophage genes are activated by the product of a particular prophage gene. C) The phage genome replicates along with the host genome. D) Certain environmental triggers can cause the phage to exit the host genome, switching from the lytic to the lysogenic. E) The phage DNA is incorporated by crossing over into any nonspecific site on the host cell's DNA.
C
A hypothetical bacterium swims among human intestinal contents until it finds a suitable location on the intestinal lining. It adheres to the intestinal lining using a feature that also protects it from phagocytes, bacteriophages, and dehydration. Fecal matter from a human in whose intestine this bacterium lives can spread the bacterium, even after being mixed with water and boiled. The bacterium is not susceptible to the penicillin family of antibiotics. It contains no plasmids and relatively little peptidoglycan. 54) Adherence to the intestinal lining by this bacterium is due to its possession of A) fimbriae. B) pili. C) a capsule. D) a flagellum. E) a cell wall with an outer lipopolysaccharide membrane.
C
A hypothetical bacterium swims among human intestinal contents until it finds a suitable location on the intestinal lining. It adheres to the intestinal lining using a feature that also protects it from phagocytes, bacteriophages, and dehydration. Fecal matter from a human in whose intestine this bacterium lives can spread the bacterium, even after being mixed with water and boiled. The bacterium is not susceptible to the penicillin family of antibiotics. It contains no plasmids and relatively little peptidoglycan. 55) What should be true of the cell wall of this bacterium? A) Its innermost layer is composed of a phospholipid bilayer. B) After it has been subjected to Gram staining, the cell should remain purple. C) It has an outer membrane of lipopolysaccharide. D) It is mostly composed of a complex, cross-linked polysaccharide. E) Two of the responses above are correct.
C
A hypothetical bacterium swims among human intestinal contents until it finds a suitable location on the intestinal lining. It adheres to the intestinal lining using a feature that also protects it from phagocytes, bacteriophages, and dehydration. Fecal matter from a human in whose intestine this bacterium lives can spread the bacterium, even after being mixed with water and boiled. The bacterium is not susceptible to the penicillin family of antibiotics. It contains no plasmids and relatively little peptidoglycan. 58) The cell also lacks F factors and F plasmids. Upon its death, this bacterium should be able to participate in A) conjugation. B) transduction. C) transformation. D) Three of the responses above are correct. E) Two of the responses above are correct.
C
A hypothetical bacterium swims among human intestinal contents until it finds a suitable location on the intestinal lining. It adheres to the intestinal lining using a feature that also protects it from phagocytes, bacteriophages, and dehydration. Fecal matter from a human in whose intestine this bacterium lives can spread the bacterium, even after being mixed with water and boiled. The bacterium is not susceptible to the penicillin family of antibiotics. It contains no plasmids and relatively little peptidoglycan. 59) This bacterium derives nutrition by digesting human intestinal contents (in other words, food). Thus, this bacterium should be an A) aerobic chemoheterotroph. B) aerobic chemoautotroph. C) anaerobic chemoheterotroph. D) anaerobic chemoautotroph.
C
A hypothetical bacterium swims among human intestinal contents until it finds a suitable location on the intestinal lining. It adheres to the intestinal lining using a feature that also protects it from phagocytes, bacteriophages, and dehydration. Fecal matter from a human in whose intestine this bacterium lives can spread the bacterium, even after being mixed with water and boiled. The bacterium is not susceptible to the penicillin family of antibiotics. It contains no plasmids and relatively little peptidoglycan. 60) This bacterium derives nutrition by digesting human intestinal contents (in other words, food). Humans lacking this bacterium have no measurable reproductive advantage or disadvantage relative to humans who harbor this bacterium. Consequently, the bacterium can be properly described as which of the following? 1. symbiont 2. endosymbiont 3. mutualist
C
Figure 27.2 depicts changes to the amount of DNA present in a recipient cell that is engaged in conjugation with an Hfr cell. Hfr cell DNA begins entering the recipient cell at Time A. Assume that reciprocal crossing over occurs (in other words, a fragment of the recipient's chromosome is exchanged for a homologous fragment from the Hfr cell's DNA). Use Figure 27.2 to answer the following question. Figure 27.2 47) How is the recipient cell different at Time D than it was at Time A? A) It has a greater number of genes.
C
Figure 27.2 depicts changes to the amount of DNA present in a recipient cell that is engaged in conjugation with an Hfr cell. Hfr cell DNA begins entering the recipient cell at Time A. Assume that reciprocal crossing over occurs (in other words, a fragment of the recipient's chromosome is exchanged for a homologous fragment from the Hfr cell's DNA). Use Figure 27.2 to answer the following question. Figure 27.2 48) Which two processes are responsible for the shape of the curve at Time B? 1. transduction
C
Poliovirus is a positive-sense RNA virus of the picornavirus group. At its 5' end, the RNA genome has a viral protein (VPg) instead of a 5' cap. This is followed by a nontranslated leader sequence, and then a single long protein coding region (~7,000 nucleotides), followed by a poly-A tail. Observations were made that used radioactive amino acid analogues. Short period use of the radioactive amino acids result in labeling of only very long proteins, while longer periods of labeling result in several different short polypeptides. 32) What part of the poliovirus would first interact with host cell ribosomes to mediate translation? A) the poly-A tail B) the leader sequence C) the VPg protein D) the AUG in the leader sequence E) the AUG at the start of the coding sequence
C
Poliovirus is a positive-sense RNA virus of the picornavirus group. At its 5' end, the RNA genome has a viral protein (VPg) instead of a 5' cap. This is followed by a nontranslated leader sequence, and then a single long protein coding region (~7,000 nucleotides), followed by a poly-A tail. Observations were made that used radioactive amino acid analogues. Short period use of the radioactive amino acids result in labeling of only very long proteins, while longer periods of labeling result in several different short polypeptides. 33) What conclusion is most consistent with the results of the radioactive labeling experiment? A) The host cell cannot translate viral protein with the amino acid analogues. B) Host cell ribosomes only translate the viral code into short polypeptides. C) The RNA is only translated into a single long polypeptide, which is then cleaved into shorter ones. D) The RNA is translated into short polypeptides, which are subsequently assembled into large ones.
C
Some viruses can be crystallized and their structures analyzed. One such virus is Desmodium, or yellow mottle virus, which infects beans. This is a member of the tymovirus group and has a single-stranded RNA genome of ~6,300 nucleotides. Its virion is 25—30 nm in diameter, and is made up of 180 copies of a single capsid protein that self-associate to form each capsomere, which has icosahedral symmetry with 20 facets. 28) If this virus has capsomeres with 20 facets, how many proteins form each one? A) 1 B) 5 C) ~6 D) ~20 E) ~180
C
Some viruses can be crystallized and their structures analyzed. One such virus is Desmodium, or yellow mottle virus, which infects beans. This is a member of the tymovirus group and has a single-stranded RNA genome of ~6,300 nucleotides. Its virion is 25—30 nm in diameter, and is made up of 180 copies of a single capsid protein that self-associate to form each capsomere, which has icosahedral symmetry with 20 facets. 30) If this virus has a positive RNA strand as its genome, it begins the infection by using this strand as mRNA. Therefore, which of the following do you expect to be able to measure? A) replication rate B) transcription rate C) translation rate D) accumulation of new ribosomes E) formation of new transcription factors
C
The following table depicts characteristics of five prokaryotic species (A—E). Use the information in the table to answer the following question. 63) Which two species should have much more phospholipid, in the form of bilayers, in their cytoplasms than most other bacteria? A) species A and B B) species A and C C) species B and E D) species C and D E) species C and E
C
The following table depicts characteristics of five prokaryotic species (A—E). Use the information in the table to answer the following question. 64) Which species should be able to respond most readily to taxes (plural of taxis)? A) species A B) species B C) species C D) species D E) species E
C
The following table depicts characteristics of five prokaryotic species (A—E). Use the information in the table to answer the following question. 65) How many of these species probably have a cell wall that partly consists of an outer membrane of lipopolysaccharide? A) only one species B) two species C) three species D) four species E) all five species
C
The following table depicts characteristics of five prokaryotic species (A—E). Use the information in the table to answer the following question. 67) Species D is pathogenic if it gains access to the human intestine. Which other species, if it coinhabited a human intestine along with species D, is most likely to result in a recombinant species that is both pathogenic and resistant to some antibiotics? A) species A B) species B C) species C D) species D E) species E
C
The herpes viruses are very important enveloped DNA viruses that cause disease in all vertebrate species and in some invertebrates such as oysters. Some of the human ones are herpes simplex (HSV) I and II, causing facial and genital lesions, and the varicella-zoster (VSV), causing chicken pox and shingles. Each of these three actively infect nervous tissue. Primary infections are fairly mild, but the virus is not then cleared from the host; rather, viral genomes are maintained in cells in a latent phase. The virus can then reactivate, replicate again, and be infectious to others. 42) In order to be able to remain latent in an infected live cell, HSV must be able to shut down what process? A) DNA replication B) transcription of viral genes C) apoptosis of a virally infected cell D) all immune responses E) interaction with histones
C
You isolate an infectious substance that is capable of causing disease in plants, but you do not know whether the infectious agent is a bacterium, virus, viroid, or prion. You have four methods at your disposal that you can use to analyze the substance in order to determine the nature of the infectious agent. I. treating the substance with nucleases that destroy all nucleic acids and then determining whether it is still infectious II. filtering the substance to remove all elements smaller than what can be easily seen under a light microscope III. culturing the substance by itself on nutritive medium, away from any plant cells IV. treating the sample with proteases that digest all proteins and then determining whether it is still infectious 38) If you already knew that the infectious agent was either bacterial or viral, which treatment would allow you to distinguish between the
C
14) Which of the following is an important source of endotoxin in gram-negative species? A) endospore B) sex pilus C) flagellum D) cell wall E) capsule
D
17) Regarding prokaryotic genetics, which statement is correct? A) Crossing over during prophase I introduces some genetic variation. B) Prokaryotes feature the union of haploid gametes, as do eukaryotes. C) Prokaryotes exchange some of their genes by conjugation, the union of haploid gametes, and transduction. D) Mutation is a primary source of variation in prokaryote populations. E) Prokaryotes skip sexual life cycles because their life cycle is too short.
D
18) What are prions? A) mobile segments of DNA B) tiny molecules of RNA that infect plants C) viral DNA that has had to attach itself to the host genome D) misfolded versions of normal brain protein E) viruses that invade bacteria
D
22) Match the numbered terms to the description that follows. Choose all appropriate terms. 1. autotroph 2. heterotroph 3. phototroph 4. chemotroph a prokaryote that obtains both energy and carbon as it decomposes dead organisms A) 1 only B) 4 only
D
23) Match the numbered terms to the description that follows. Choose all appropriate terms. 1. autotroph 2. heterotroph 3. phototroph 4. chemotroph an organism that obtains both carbon and energy by ingesting prey A) 1 only B) 4 only C) 1 and 3
D
23) Which of the three types of viruses shown above would you expect to include glycoproteins? A) I only B) II only C) III only D) I and II only E) all three
D
27) Carl Woese and collaborators identified two major branches of prokaryotic evolution. What was the basis for dividing prokaryotes into two domains? A) microscopic examination of staining characteristics of the cell wall B) metabolic characteristics such as the production of methane gas C) metabolic characteristics such as chemoautotrophy and photosynthesis D) genetic characteristics such as ribosomal RNA sequences E) ecological characteristics such as the ability to survive in extreme environments
D
29) If archaeans are more closely related to eukaryotes than to bacteria, then which of the following is a reasonable prediction? A) Archaean DNA should have no introns. B) Archaean chromosomes should have no protein bonded to them. C) Archaean DNA should be single-stranded. D) Archaean ribosomes should be larger than typical prokaryotic ribosomes. E) Archaeans should lack cell walls.
D
30) Which of the following traits do archaeans and bacteria share? 1. composition of the cell wall 2. presence of plasma membrane 3. lack of a nuclear envelope 4. identical rRNA sequences A) 1 only B) 3 only C) 1 and 3 D) 2 and 3
D
34) The termite gut protist, Mixotricha paradoxa, has at least two kinds of bacteria attached to its outer surface. One kind is a spirochete that propels its host through the termite gut. A second type of bacteria synthesizes ATP, some of which is used by the spirochetes. The locomotion provided by the spirochetes introduces the ATP-producing bacteria to new food sources. Which term(s) is (are) applicable to the relationship between the two kinds of bacteria? 1. mutualism 2. parasitism 3. symbiosis 4. metabolic cooperation A) 1 only B) 1 and 2 C) 2 and 3 D) 1, 3, and 4
D
36) If all prokaryotes on Earth suddenly vanished, which of the following would be the most likely and most direct result? A) The number of organisms on Earth would decrease by 1020%. B) Human populations would thrive in the absence of disease. C) Bacteriophage numbers would dramatically increase. D) The recycling of nutrients would be greatly reduced, at least initially. E) There would be no more pathogens on Earth.
D
4) The predatory bacterium, Bdellovibrio bacteriophorus, drills into a prey bacterium and, once inside, digests it. In an attack upon a gram-negative bacterium that has a slimy cell covering, what is the correct sequence of structures penetrated by B. bacteriophorus on its way to the prey's cytoplasm? 1. membrane composed mostly of lipopolysaccharide 2. membrane composed mostly of phospholipids 3. peptidoglycan 4. capsule A) 2, 4, 3, 1 B) 1, 3, 4, 2 C) 1, 4, 3, 2 D) 4, 1, 3, 2 E) 4, 3, 1, 2
D
44) Emerging viruses arise by A) mutation of existing viruses. B) the spread of existing viruses to new host species. C) the spread of existing viruses more widely within their host species. D) mutation of existing viruses, the spread of existing viruses to new host species, and the spread of existing viruses more widely within their host species. E) none of these.
D
46) A bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage protein coat and T4 phage DNA. The new phages produced would have A) T2 protein and T4 DNA. B) T2 protein and T2 DNA. C) a mixture of the DNA and proteins of both phages. D) T4 protein and T4 DNA. E) T4 protein and T2 DNA
D
5) Which of the following accounts for someone who has had a herpesvirus-mediated cold sore or genital sore getting flare-ups for the rest of his or her life? A) re-infection by a closely related herpesvirus of a different strain B) re-infection by the same herpesvirus strain C) co-infection with an unrelated virus that causes the same symptoms D) copies of the herpesvirus genome permanently maintained in host nuclei E) copies of the herpesvirus genome permanently maintained in host cell cytoplasm
D
7) Which of the following is characteristic of the lytic cycle? A) Many bacterial cells containing viral DNA are produced. B) Viral DNA is incorporated into the host genome. C) The viral genome replicates without destroying the host. D) A large number of phages are released at a time. E) The virus-host relationship usually lasts for generations.
D
A hypothetical bacterium swims among human intestinal contents until it finds a suitable location on the intestinal lining. It adheres to the intestinal lining using a feature that also protects it from phagocytes, bacteriophages, and dehydration. Fecal matter from a human in whose intestine this bacterium lives can spread the bacterium, even after being mixed with water and boiled. The bacterium is not susceptible to the penicillin family of antibiotics. It contains no plasmids and relatively little peptidoglycan. 53) This bacterium's ability to survive in a human who is taking penicillin pills may be due to the presence of 1. penicillin-resistance genes 2. a secretory system that removes penicillin from the cell 3. a gram-positive cell wall 4. a gram-negative cell wall 5. an endospore
D
A hypothetical bacterium swims among human intestinal contents until it finds a suitable location on the intestinal lining. It adheres to the intestinal lining using a feature that also protects it from phagocytes, bacteriophages, and dehydration. Fecal matter from a human in whose intestine this bacterium lives can spread the bacterium, even after being mixed with water and boiled. The bacterium is not susceptible to the penicillin family of antibiotics. It contains no plasmids and relatively little peptidoglycan. 56) Some of the proteins that allow this bacterium to swim are related (in an evolutionary sense) to proteins that A) attach to the single chromosome. B) act as restriction enzymes. C) synthesize peptidoglycan for the cell wall. D) move penicillin out of the cell. E) comprise its ribosomes.
D
A hypothetical bacterium swims among human intestinal contents until it finds a suitable location on the intestinal lining. It adheres to the intestinal lining using a feature that also protects it from phagocytes, bacteriophages, and dehydration. Fecal matter from a human in whose intestine this bacterium lives can spread the bacterium, even after being mixed with water and boiled. The bacterium is not susceptible to the penicillin family of antibiotics. It contains no plasmids and relatively little peptidoglycan. 57) In which feature(s) should one be able to locate a complete chromosome of this bacterium? 1. nucleolus 2. prophage 3. endospore 4. nucleoid A) 4 only
D
Figure 27.2 depicts changes to the amount of DNA present in a recipient cell that is engaged in conjugation with an Hfr cell. Hfr cell DNA begins entering the recipient cell at Time A. Assume that reciprocal crossing over occurs (in other words, a fragment of the recipient's chromosome is exchanged for a homologous fragment from the Hfr cell's DNA). Use Figure 27.2 to answer the following question. Figure 27.2 46) What is occurring at Time C that is decreasing the DNA content?
D
In 1971, David Baltimore described a scheme for classifying viruses based on how the virus produces mRNA. The table below shows the results of testing five viruses for nuclease specificity, the ability of the virus to act as an mRNA, and presence (+) or absence (-) of its own viral polymerase (SEE IMAGE) 35) Based on the above table, which virus meets the Baltimore requirements for a retrovirus? A) A B) B C) C D) D
D
The following table depicts characteristics of five prokaryotic species (A—E). Use the information in the table to answer the following question. 68) Which species might be able to include Hfr cells? A) species A B) species B C) species C D) species D E) species E
D
The herpes viruses are very important enveloped DNA viruses that cause disease in all vertebrate species and in some invertebrates such as oysters. Some of the human ones are herpes simplex (HSV) I and II, causing facial and genital lesions, and the varicella-zoster (VSV), causing chicken pox and shingles. Each of these three actively infect nervous tissue. Primary infections are fairly mild, but the virus is not then cleared from the host; rather, viral genomes are maintained in cells in a latent phase. The virus can then reactivate, replicate again, and be infectious to others. 41) In electron micrographs of HSV infection, it can be seen that the intact virus initially reacts with cell surface proteoglycans, then with specific receptors. This is later followed by viral capsids docking with nuclear pores. Afterward, the capsids go from being full to being "empty." Which of the following best fits these observations? A) Viral capsids are needed for the cell to become infected; only the capsids enter the nucleus.
D
You isolate an infectious substance that is capable of causing disease in plants, but you do not know whether the infectious agent is a bacterium, virus, viroid, or prion. You have four methods at your disposal that you can use to analyze the substance in order to determine the nature of the infectious agent. I. treating the substance with nucleases that destroy all nucleic acids and then determining whether it is still infectious II. filtering the substance to remove all elements smaller than what can be easily seen under a light microscope III. culturing the substance by itself on nutritive medium, away from any plant cells IV. treating the sample with proteases that digest all proteins and then determining whether it is still infectious 39) Which treatment would you use to determine if the agent is a prion? A) I only
D
10) Which statement about the genomes of prokaryotes is correct? A) Prokaryotic genomes are diploid throughout most of the cell cycle. B) Prokaryotic chromosomes are sometimes called plasmids. C) Prokaryotic cells have multiple chromosomes, "packed" with a relatively large amount of protein. D) The prokaryotic chromosome is not contained within a nucleus but, rather, is found at the nucleolus. E) Prokaryotic genomes are composed of circular DNA.
E
12) Which viruses have single-stranded RNA that acts as a template for DNA synthesis? A) lytic phages B) proviruses C) viroids D) bacteriophages E) retroviruses
E
19) Which of the following is least associated with the others? A) horizontal gene transfer B) genetic recombination C) conjugation D) transformation E) binary fission
E
20) In Fred Griffith's experiments, harmless R strain pneumococcus became lethal S strain pneumococcus as the result of which of the following? 1. horizontal gene transfer 2. transduction 3. conjugation 4. transformation 5. genetic recombination A) 2 only B) 4 only C) 2 and 5
E
73) Genetic variation in bacterial populations cannot result from A) transduction. B) transformation C) conjugation D) mutation. E) meiosis.
E
21) Which of the following series best reflects what we know about how the flu virus moves between species? A) An avian flu virus undergoes several mutations and rearrangements such that it is able to be transmitted to other birds and then to humans. B) The flu virus in a pig is mutated and replicated in alternate arrangements so that humans who eat the pig products can be infected. C) A flu virus from a human epidemic or pandemic infects birds; the birds replicate the virus differently and then pass it back to humans. D) An influenza virus gains new sequences of DNA from another virus, such as a herpesvirus; this enables it to be transmitted to a human host. E) An animal such as a pig is infected with more than one virus, genetic recombination occurs, the new virus mutates and is passed to a new species such as a bird, the virus mutates and can be transmitted to humans.
E
22) Which of the following is the most probable fate of a newly emerging virus that causes high mortality in its host? A) It is able to spread to a large number of new hosts quickly because the new hosts have no immunological memory of them. B) The new virus replicates quickly and undergoes rapid adaptation to a series of divergent hosts. C) A change in environmental conditions such as weather patterns quickly forces the new virus to invade new areas. D) Sporadic outbreaks will be followed almost immediately by a widespread pandemic. E) The newly emerging virus will die out rather quickly or will mutate to be far less lethal.
E
24) Which of the three types of viruses shown above would you expect to include a capsid(s)? A) I only B) II only C) III only D) I and II only E) all three
E
26) In the figure, when new viruses are being assembled (IV), what mediates the assembly? A) host cell chaperones B) assembly proteins coded for by the host nucleus C) assembly proteins coded for by the viral genes D) viral RNA intermediates E) nothing; they self-assemble
E
26) Mitochondria are thought to be the descendants of certain alpha proteobacteria. They are, however, no longer able to lead independent lives because most genes originally present on their chromosome have moved to the nuclear genome. Which phenomenon accounts for the movement of these genes? A) plasmolysis B) conjugation C) translation D) endocytosis E) horizontal gene transfer
E
3) The host range of a virus is determined by A) the enzymes carried by the virus. B) whether its nucleic acid is DNA or RNA. C) the proteins in the host's cytoplasm. D) the enzymes produced by the virus before it infects the cell. E) the proteins on its surface and that of the host.
E
33) A fish that has been salt-cured subsequently develops a reddish color. You suspect that the fish has been contaminated by the extreme halophile, Halobacterium. Which of these features of cells removed from the surface of the fish, if confirmed, would support your suspicion? 1. the presence of the same photosynthetic pigments found in cyanobacteria 2. cell walls that lack peptidoglycan 3. cells that are isotonic to conditions on the surface of the fish 4. cells containing bacteriorhodopsin 5. the presence of very large numbers of ion pumps in its plasma membrane A) 2 and 5 B) 3 and 4 C) 1, 4, and 5 D) 3, 4, and 5 E) 2, 3, 4, and 5
E
39) Broad-spectrum antibiotics inhibit the growth of most intestinal bacteria. Consequently, assuming that nothing is done to counter the reduction of intestinal bacteria, a hospital patient who is receiving broad-spectrum antibiotics is most likely to become A) unable to fix carbon dioxide. B) antibiotic resistant. C) unable to fix nitrogen. D) unable to synthesize peptidoglycan. E) deficient in certain vitamins and nutrients.
E
6) In a bacterium that possesses antibiotic resistance and the potential to persist through very adverse conditions, such as freezing, drying, or high temperatures, DNA should be located within, or be part of, which structures? 1. nucleoid region 2. endospore 3. fimbriae 4. plasmids A) 1 only B) 1 and 2 only
E
Nitrogenase, the enzyme that catalyzes nitrogen fixation, is inhibited whenever free O₂ reaches a critical concentration. Consequently, nitrogen fixation cannot occur in cells wherein photosynthesis produces free O₂. Consider the colonial aquatic cyanobacterium, Anabaena, whose heterocytes are described as having "...a thickened cell wall that restricts entry of O₂ produced by neighboring cells. Intracellular connections allow heterocysts to transport fixed nitrogen to neighboring cells in exchange for carbohydrates." 61) Given that the enzymes that catalyze nitrogen fixation are inhibited by oxygen, what are two "strategies" that nitrogen-fixing prokaryotes might use to protect these enzymes from oxygen? 1. couple them with photosystem II (the photosystem that splits water molecules) 2. package them in membranes that are impermeable to all gases 3. be obligate anaerobes
E
Some viruses can be crystallized and their structures analyzed. One such virus is Desmodium, or yellow mottle virus, which infects beans. This is a member of the tymovirus group and has a single-stranded RNA genome of ~6,300 nucleotides. Its virion is 25—30 nm in diameter, and is made up of 180 copies of a single capsid protein that self-associate to form each capsomere, which has icosahedral symmetry with 20 facets. 29) How many nucleotides of the genome would you expect to find in one capsid? A) 1 B) ~6 C) ~20 D) ~180 E) ~6,300
E
The following table depicts characteristics of five prokaryotic species (A—E). Use the information in the table to answer the following question. 69) Which species is most self-sustaining in terms of obtaining nutrition in environments containing little fixed nitrogen or carbon? A) species A B) species B C) species C D) species D E) species E
E
The following table depicts characteristics of five prokaryotic species (A—E). Use the information in the table to answer the following question. 72) Which species is probably an important contributor to the base of aquatic food chains as a primary producer? A) species A B) species B C) species C D) species D E) species E
E
