Chapter 24 Early Life and Diversification of Prokaryotes

35) 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) Genetic prospecting has recently revealed the existence of many previously unknown archaean species.

14) 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 as a result of water loss from the cell. 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) undergo death as a result of water loss from the cell.

7) The synthesis of new DNA requires the prior existence of oligonucleotides to serve as primers. On Earth, these primers are small RNA molecules. This latter observation is evidence in support of the hypothesized existence of A) a snowball Earth. B) earlier genetic systems than those based on DNA. C) the abiotic synthesis of organic monomers. D) the delivery of organic matter to Earth by meteors and comets. E) the endosymbiotic origin of mitochondria and chloroplasts.

B) earlier genetic systems than those based on DNA.

4) Photoautotrophs use A) light as an energy source and methane as a carbon source. B) light as an energy source and CO2 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.

B) light as an energy source and CO2 as a carbon source.

21) Prokaryotes' essential genetic information is located in the A) nucleolus. B) nucleoid. C) nucleosome. D) plasmids. E) exospore.

B) nucleoid.

27) 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) the rapid spread of tetracycline resistance to other bacteria in that habitat.

39) 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) 2, 4, and 5

9) Approximately how far back in time does the fossil record extend? A) 3.5 million years B) 5.0 million years C) 3.5 billion years D) 5.0 billion years

C) 3.5 billion years

12) 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) Cell walls prevent cells from dying in hypertonic conditions.

26) Which of the following obtain energy by oxidizing inorganic substances to obtain energy that is used, in part, to fix CO2? A) photoautotrophs B) photoheterotrophs C) chemoautotrophs D) chemoheterotrophs that perform decomposition E) parasitic chemoheterotrophs

C) chemoautotrophs

29) 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) Mutation is a primary source of variation in prokaryote populations.

5) 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) Only bacteria have histones associated with DNA.

45) 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 10—20%. 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) The recycling of nutrients would be greatly reduced, at least initially.

28) 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) capsule

42) 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) cell wall

1) Which of the following steps has not yet been accomplished by scientists studying the origin of life? A) synthesis of small RNA polymers by ribozymes B) abiotic synthesis of polypeptides C) formation of molecular aggregates with selectively permeable membranes D) formation of protocells that use DNA to direct the polymerization of amino acids E) abiotic synthesis of organic molecules

D) formation of protocells that use DNA to direct the polymerization of amino acids

34) 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) genetic characteristics such as ribosomal RNA sequences

47) 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) deficient in certain vitamins and nutrients.

33) 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) horizontal gene transfer

3) Genetic variation in bacterial populations cannot result from A) transduction. B) transformation. C) conjugation. D) mutation. E) meiosis.

E) meiosis.

2) How were conditions on the early Earth of more than 3 billion years ago different from those on today's Earth? A) Only early Earth was intensely bombarded by large space debris. B) Only early Earth had an oxidizing atmosphere. C) Less ultraviolet radiation penetrated early Earth's atmosphere. D) Early Earth's atmosphere had significant quantities of ozone.

A) Only early Earth was intensely bombarded by large space debris.

18) 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 unable to use a greater variety of molecules as food sources than can eukaryotes.

A) Some antibiotics can block protein synthesis in bacteria without effects in the eukaryotic host.

6) Bacteria perform the following ecological roles. Which role typically does not involve symbiosis? A) skin commensalist B) pathogen C) bioluminescent bacteria in fish D) gut mutualist E) decomposer

E) decomposer

44) 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) breaking down organic matter

7) Plantlike photosynthesis that releases O2 occurs in A) cyanobacteria. B) chlamydias. C) archaea. D) actinomycetes. E) chemoautotrophic bacteria.

A) cyanobacteria.

38) 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) extreme halophiles

20) 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) lack antibiotic-resistant genes.

16) 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 D) 3 and 4 E) 3 and 5

B) 1 and 3

12) Which two of the following questions 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? 3. If the nuclei of the photosynthetic cells contain the genes that code for nitrogen fixation, how can these cells fail to perform nitrogen fixation? 4. If the nuclei of the heterocysts contain the genes that code for photosynthesis, how can these cells fail to perform photosynthesis? 5. If the cell walls of Anabaena's heterocysts are permeable to N2, how is it that N2 doesn't diffuse out of the heterocysts before it can be fixed? 6. If the thick cell walls of the heterocysts exclude entry of oxygen gas, how is it that they don't also exclude the entry of nitrogen gas? A) 1 and 3 B) 1 and 6 C) 2 and 5 D) 3 and 4 E) 4 and 6

B) 1 and 6

25) 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 energy from light A) 1 only B) 3 only C) 1 and 3 D) 2 and 4 E) 1, 3, and 4

B) 3 only

1) 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) Closing previously opened containers: prevents more bacteria from entering, and excludes O2.

41) 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) They are subject to lysis in hypotonic conditions.

5) Which of the following is a defining characteristic that all protobionts had in common? A) the ability to synthesize enzymes B) a surrounding membrane or membrane-like structure C) RNA genes D) the ability to replicate RNA

B) a surrounding membrane or membrane-like structure

1) If the complex protein assemblage of the prokaryotic flagellum arose by the same general processes as those of the complex eyes of molluscs (such as squids and octopi), then A) natural selection cannot account for the rise of the prokaryotic flagellum. B) ancestral versions of this protein assemblage were either less functional or had different functions than modern prokaryotic flagella. C) scientists should accept the conclusion that neither eyes nor flagella could have arisen by evolution. D) we can conclude that both of these structures must have arisen through the direct action of an "intelligent designer."

B) ancestral versions of this protein assemblage were either less functional or had different functions than modern prokaryotic flagella.

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. 10) 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 4. commensal A) 4 only B) 1 and 2 C) 1 and 4 D) 2 and 3 E) 2 and 4

C) 1 and 4

46) 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. pathogen 5. primary producer A) 1, 3, 4 B) 2, 3, 4 C) 2, 4, 1 D) 1, 2, 5 E) 1, 2, 3

C) 2, 4, 1

8) Several scientific laboratories across the globe are involved in research concerning the origin of life on Earth. Which of these questions is currently the most problematic and would have the greatest impact on our understanding if we were able to answer it? A) How can amino acids, simple sugars, and nucleotides be synthesized abiotically? B) How can RNA molecules catalyze reactions? C) How did RNA sequences come to carry the code for amino acid sequences? D) How could polymers involving lipids and/or proteins form membranes in aqueous environments? E) How can RNA molecules act as templates for the synthesis of complementary RNA molecules?

C) How did RNA sequences come to carry the code for amino acid sequences?

11) If it were possible to conduct sophisticated microscopic and chemical analyses of microfossils found in 3.2-billion-year-old stromatolites, then one should be surprised to observe evidence of which of the following within such microfossils? I. ​double-stranded DNA II. ​a nuclear envelope III. ​a nucleoid IV. ​a nucleolus V. ​ribosomes A) II only B) III only C) II and IV D) II, III, and IV E) all five of these

C) II and IV

4) Which of the following is the correct sequence of events in the origin of life? I. ​formation of protobionts II. ​synthesis of organic monomers III. ​synthesis of organic polymers IV. ​formation of DNA-based genetic systems A) I, II, III, IV B) I, III, II, IV C) II, III, I, IV D) II, III, IV, I

C) II, III, I, IV

22) 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) If chloramphenicol inhibits prokaryotic ribosomes, should it not also inhibit mitochondrial ribosomes?

6) The first genes on Earth were probably A) DNA produced by reverse transcriptase from abiotically produced RNA. B) DNA molecules whose information was transcribed to RNA and later translated in polypeptides. C) auto-catalytic RNA molecules. D) oligopeptides located within protobionts.

C) auto-catalytic RNA molecules.

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. 5) 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) It has an outer membrane of lipopolysaccharide.

3) What is true of the amino acids that might have been delivered to Earth within carbonaceous chondrites? A) They had the same proportion of L and D isomers as Earth does today. B) Their abundance would have been dramatically reduced upon passage through early Earth's oxidizing atmosphere. C) There were more kinds of amino acids on the chondrites than are found in living organisms today. D) They were delivered in the form of polypeptides.

C) There were more kinds of amino acids on the chondrites than are found in living organisms today.

30) 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) They divide by binary fission, without mitosis or meiosis.

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. 4) 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 capsule.

17) 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) a complex "motor" embedded in the cell wall and plasma membrane.

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. 9) 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) anaerobic chemoheterotroph.

2) Fossilized stromatolites A) more than 2.8 billion years old have not been discovered. B) formed around deep-sea vents. C) resemble structures formed by bacterial communities that are found today in some shallow marine bays. D) provide evidence that plants moved onto land in the company of fungi around 500 million years ago. E) contain the first undisputed fossils of eukaryotes and date from 1.8 billion years ago.

C) resemble structures formed by bacterial communities that are found today in some shallow marine bays.

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. 8) 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) A and B E) B and C F) all of the choices are correct.

C) transformation.

43) 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 of the following terms 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 E) 2, 3, and 4

D) 1, 3, and 4

37) 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 E) 2 and 4

D) 2 and 3

23) 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 C) 1 and 3 D) 2 and 4 E) 1, 3, and 4

D) 2 and 4

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 obtains both carbon and energy by ingesting prey A) 1 only B) 4 only C) 1 and 3 D) 2 and 4 E) 1, 3, and 4

D) 2 and 4

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. 7) 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 B) 1 and 3 C) 2 and 3 D) 3 and 4 E) 2, 3, and 4

D) 3 and 4

13) 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) 4, 1, 3, 2

36) 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) Archaean ribosomes should be larger than typical prokaryotic ribosomes.

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. 6) 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 macromolecules out of the cell. E) comprise its ribosomes.

D) move macromolecules out of the cell.

2) Certain proteins of the complex motor that drives bacterial flagella are modified versions of proteins that had previously belonged to plasma membrane pumps. This evidence supports the claim that A) some structures are so complex that natural selection cannot, and will not, explain their origins. B) the power of natural selection allows it to act in an almost predictive fashion, producing organs that will be needed in future environments. C) the motors of bacterial flagella were originally synthesized abiotically. D) natural selection can produce new structures by coupling together parts of other structures. E) bacteria that possess flagella must have lost the ability to pump certain chemicals across their plasma membranes.

D) natural selection can produce new structures by coupling together parts of other structures.

15) 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 structure(s)? 1. nucleoid region 2. endospore 3. fimbriae 4. plasmids A) 1 only B) 1 and 2 only C) 1 and 4 only D) 2 and 4 only E) 1, 2, and 4

E) 1, 2, and 4

32) 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 D) 1, 3, and 5 E) 1, 4, and 5

E) 1, 4, and 5

40) 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 unable to survive salt concentrations lower than 9% 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) 2, 3, 4, and 5

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. 3) This bacterium's ability to survive in a human who is taking penicillin pills may be due to the presence of which of the following? 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 A) 1 or 5 B) 2 or 3 C) 4 or 5 D) 2, 3, or 5 E) 2, 4, or 5

E) 2, 4, or 5

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. 11) 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 4. be strict aerobes 5. package these enzymes in specialized cells or compartments that inhibit oxygen entry A) 1 and 4 B) 2 and 4 C) 2 and 5 D) 3 and 4 E) 3 and 5

E) 3 and 5

19) 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) Prokaryotic genomes are composed of circular DNA.

10) Which of the following statements provides the strongest evidence that prokaryotes evolved before eukaryotes? A) Prokaryotic cells lack nuclei. B) The meteorites that have struck Earth contain fossils only of prokaryotes. C) Laboratory experiments have produced liposomes abiotically. D) Liposomes closely resemble prokaryotic cells. E) The oldest fossilized cells resemble prokaryotes.

E) The oldest fossilized cells resemble prokaryotes.

31) 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) binary fission