Campbell Biology- Chapter 24

In what way(s), if any, is a chemoautotroph different from a chemoheterotroph? A) Chemoautotrophs can produce carbon-containing compounds for use in metabolism or for the building of its structures, whereas a chemoheterotroph must consume such compounds. B) Chemoautotrophs use light energy to produce carbon-containing compounds, whereas a chemoheterotroph uses inorganic compounds. C) Chemoautotrophs use organic compounds as an energy and carbon source, whereas chemoheterotrophs use inorganic compounds as an energy and carbon source. D) Chemoautotrophs and chemoheterotrophs are not different from one another with respect to energy and carbon sources.

A) Chemoautotrophs can produce carbon-containing compounds for use in metabolism or for the building of its structures, whereas a chemoheterotroph must consume such compounds.

The predatory bacterium Bdellovibrio bacteriovorus drills into a prey bacterium and, once inside, digests it. When the predatory bacterium attacks the gram-negative bacterium, what are the first structures penetrated by B. bacteriovorus on its way into the prey's cytoplasm? A) lipopolysaccharides and an outer membrane B) peptidoglycan layer and plasma membrane C) lipopolysaccharides and plasma membrane D) fimbriae and peptidoglycan layer

A) lipopolysaccharides and an outer membrane

On early Earth, more than 4 billion years ago, environmental conditions were very different from those today because A) only early Earth was intensely bombarded by large rocks and ice from space. 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 rocks and ice from space.

Which photograph in the figure shows the cellular structure observed in species such as Staphylococcus epidermis, Staphylococcus aureus, and Streptococcus pneumoniae? A) spherical B) rod-Shaped C) spiral

A) spherical

Bacteria can rarely colonize and contaminate foods with high sugar content, such as syrup, honey, jelly, or bags of sugar, even if these products are left open in warm temperatures. The reason they do not become contaminated is because bacteria that encounter these foods A) undergo death as a result of water loss from the cell. B) are unable to metabolize the glucose, sucrose, or fructose and thus starve to death. C) experience lysis. D) are obligate anaerobes. E) are unable to move through these thick and viscous materials.

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

The majority of a bacterium's key genetic information is located in the A) flagella. B) nucleoid. C) capsule. D) plasmids. E) endospore.

B) nucleoid.

Which of the following describes an organism that obtains energy from light? A) autotroph only B) phototroph only C) autotroph and phototroph D) heterotroph and chemotroph E) autotroph, phototroph, and chemotroph

B) phototroph only

Which of the following traits do archaeans and bacteria share? A) composition of the cell wall B) presence of plasma membrane C) a nuclear envelope D) identical rRNA sequences

B) presence of plasma membrane

In general, what is the primary ecological role of prokaryotes? A) parasitizing eukaryotes, thus causing diseases B) recycling soil nutrients and 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) recycling soil nutrients and breaking down organic matter

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

Imagine a person ingests some food that causes them to become ill and have symptoms such as a diarrhea and fever. What kind of pathogenic bacterial poison could the person have been exposed to? A) bacteria that produced exotoxins in the person's system B) bacteria that died, and endotoxins were then released C) both exotoxins or endotoxins are possible sources of the illness

C) both exotoxins or endotoxins are possible sources of the illness

Which of the following describes an organism that oxidizes inorganic substances to obtain energy that is used, in part, to fix CO2 from the atmosphere? A) photoautotrophs B) photoheterotrophs C) chemoautotrophs D) chemoheterotrophs that perform decomposition

C) chemoautotrophs

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. A) nutrient recycler, commensalist, pathogen B) mutualist, commensalist, pathogen C) mutualist, pathogen, nutrient recycler D) nutrient recycler, mutualist, primary producer E) nutrient recycler, mutualist, commensalist

C) mutualist, pathogen, nutrient recycler

Why can prokaryotic population numbers be magnitudes larger than populations of multicellular eukaryotes? A) Prokaryotes are small only. B) Prokaryotes are small and have short generation times only. C) Prokaryotes reproduce by binary fission, often have short generation times, and have cell walls primarily made of cellulose. D) Prokaryotes are small, reproduce by binary fission, and often have short generation times.

D) Prokaryotes are small, reproduce by binary fission, and often have short generation times.

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.

The interactions of prokaryotes with humans are A) only negative. B) only positive. C) only mutualistic. D) both negative and positive.

D) both negative and positive.

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

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

Thiobacillus ferrooxidans is a type of bacteria that oxidizes iron compounds for energy and then uses that energy to build carbohydrates. We might best recognize this bacterium as the rust- colored ring that builds up inside toilet bowls. Thiobacillus ferrooxidans is an example of a A) photoautotroph. B) chemoheterotroph. C) photoheterotroph. D) chemoautotroph.

D) chemoautotroph.

Scientists have identified two major branches of prokaryotic evolution. What was the basis for dividing prokaryotes into two domains? A) microscopically observed 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

Which of the following describes an organism that obtains both carbon and energy by ingesting prey? A) autotroph only B) chemotroph only C) autotroph and phototroph D) heterotroph and chemotroph E) autotroph, phototroph, and chemotroph

D) heterotroph and chemotroph

Please use the following information to answer the question(s) below. 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 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.What should be true of the cell wall of this bacterium?

It has an outer membrane of lipopolysaccharide.

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.

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) transduction B) conjugation C) translation D) binary fission E) horizontal gene transfer

E) horizontal gene transfer

According to scientists' hypotheses, prokaryotes most likely evolved prior to eukaryotes because A) prokaryotic cells lack nuclei. B) the meteorites that have struck Earth contain fossils only of prokaryotes. C) laboratory experiments have produced ribosomes abiotically. D) ribosomes closely resemble prokaryotic cells. E) the oldest fossilized cells resemble prokaryotes.

E) the oldest fossilized cells resemble prokaryotes.

Data were collected from the heterocysts of a nitrogen-fixing cyanobacterium inhabiting equatorial ponds. Study the following figure, and choose the most likely explanation for the shape of the curve. Img 8

Enough O2 enters heterocysts during hours of peak photosynthesis to have a somewhat inhibitory effect on nitrogen fixation.

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.

IMG 10 - E. coli cells typically make most of their ATP by metabolizing glucose. Under the conditions of this experiment, what should be true of E. coli's generation time (especially early in the course of the experiment, but less so later on)?

Generation time should be slower than in the typical environment.

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. Which of the following question 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?

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?

IMG 11- Which question arising from the results depicted in the figure is most interesting from a genetic perspective and has the greatest potential to increase our knowledge base?

If reciprocal crossing over could occur even if the piece of donated Hfr DNA is identical to the homologous portion of the recipient's chromosome, what prevents this from occurring?

IMG 11 - How is the recipient cell different at time D than it was at time A?

It has a different sequence of base pairs.

.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 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.Adherence to the intestinal lining by this bacterium is due to its possession of. . .

a capsule

IMG 10 - If new genetic variation in the experimental populations arose solely by spontaneous mutations, then the most effective process for subsequently increasing the number of individuals that possess all of these beneficial mutations is

binary fission.

Several scientific laboratories across the globe are performing research concerning the origin of life on Earth. Suppose one of these laboratories conducts abiotic experiment(s) to test the potential for hydrogen bonding between various nucleic acids and amino acids. Which of the following results of such experiments are most consistent with our current understanding of Earth's first genetic systems?

img 7 B (the one with most on RNA-amino acid and little RNA-DNA)

What structure(s) can allow a bacterium to persist, often over extended periods of time, in extreme environments such as those lacking in nutrients, dehydrating, and freezing, or in very hot temperatures? A) nucleoids B) capsules or endospores C) plasmids D) peptidoglycan E) fimbriae

B) capsules or endospores

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 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.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. endotoxin 3. mutualist 4. commensal

1 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 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.The cell also lacks F factors and F plasmids. Which mechanism(s) of genetic recombination can possibly take place? 1. conjugation 2. transduction 3. transformation

2 & 3

IMG 11- Which two processes are responsible for the shape of the curve at time B? 1. transduction 2. entry of single-stranded Hfr DNA 3. rolling circle replication of single-stranded Hfr DNA 4. conjugation

2 & 3

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 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.In which feature(s) should you be able to locate a complete chromosome of this bacterium? 1. nucleolus 2. pili 3. endospore 4. nucleoid

3 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 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.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 gram-positive cell wall 3. a gram-negative cell wall 4. an endospore

3 or 4

Thermoacidophiles are archaeans that are able to successfully live and reproduce in environments that are acidic, have high sulfur content and temperatures, and have little organic material. 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.) IMG 12

A (two hills)

The structure of a prokaryotic ribosome is not the same as a ribosome in an animal cell. As a result, which of the following is correct? A) Some antibiotics can block protein synthesis in bacteria without harming 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 harming the eukaryotic host.

What is one key difference between transduction and conjugation? A) Transduction involves DNA being incorporated via a virus from one cell to another. B) Conjugation involves DNA being incorporated via a virus from one cell to another. C) Conjugation involves DNA transfer from two different species, whereas transduction is within the same species. D) Transduction involves the direct joining of prokaryotic plasma membranes and then genetic transfer.

A) Transduction involves DNA being incorporated via a virus from one cell to another.

In 2009, which of the following did scientists discover was possible on early Earth? A) abiotic synthesis of RNA monomers B) bacterial cell walls made mainly of chitin C) gram-positive bacteria with outer membranes that contain lipopolysaccharides D) gram-negative bacteria with cell walls composed of a thick layer of peptidoglycan

A) abiotic synthesis of RNA monomers

Assuming that each possesses a cell wall, which of these 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

If a bacterium regenerates from an endospore that did not possess any of the plasmids that were contained in its original parent cell but does contain the large circular chromosome, the regenerated bacterium will probably also A) lack antibiotic-resistant genes. B) lack a cell wall. C) lack chromosomes. D) lack water in its cytoplasm. E) be unable to survive in its normal environment.

A) lack antibiotic-resistant genes.

What is a main difference between endotoxins and exotoxins? A) Endotoxins are proteins, and exotoxins are lipopolysaccharides. B) Endotoxins are lipopolysaccharides and thus structurally integral to the bacterium, whereas exotoxins are proteins that are secreted by living bacteria. C) Exotoxins are released only when the bacteria die and their cell walls break down. D) Exotoxins are made of RNA, and endotoxins are made of DNA.

B) Endotoxins are lipopolysaccharides and thus structurally integral to the bacterium, whereas exotoxins are proteins that are secreted by living bacteria.

The first genetic material on early Earth was most likely A) DNA. B) RNA. C) peptidoglycan. D) protocells.

B) RNA.

What is the best explanation for how a motor unit of a flagellum can stay in its correct location within a bacterial cell wall and membrane? A) It is attached to the membrane using proteinaceous fibers. B) Some portions of the proteins of the motor unit have regions of polar hydrophilic amino acids, and others have non-polar hydrophobic amino acids. C) The force of the flagellum filament keeps the motor unit pinned to the membrane. D) The rod portion of the motor unit forms a tube-like structure that uses the suction of water to keep it in place.

B) Some portions of the proteins of the motor unit have regions of polar hydrophilic amino acids, and others have non-polar hydrophobic amino acids

Suppose bacteria are grown on a petri dish that contains nutrient agar and the antibiotic ampicillin. After observing the bacteria growth on the plate for two days, you notice that only some of the bacteria have survived. What is a plausible explanation for your observations? A) Some of the bacterial DNA was not able to replicate because it lacked some of its own genetic material. B) The bacteria that survived were transformed with a plasmid that contains the resistance gene for ampicillin. C) The pili of the bacterial could not attach to the ampicillin. D) F plasmids were not present to transfer bacterial DNA.

B) The bacteria that survived were transformed with a plasmid that contains the resistance gene for ampicillin.

Bacteria are able to adhere to substrates and to other individuals by using which structures? A) capsules and endospores B) capsules and fimbriae C) endospores and fimbriae D) fimbriae and plasmids E) fimbriae and flagella

B) capsules and fimbriae

Two prokaryotes are shown in the figure that have additional cellular membranes within the plasma membrane. What functions could the respiratory membranes and the thylakoid membranes provide? A) These are both autotrophic evolutionary adaptations to allow organic molecule production. B) The respiratory membrane allows a functional electron transport chain and oxidative phosphorylation of ATP. C) The thylakoid membrane allows the fixation of CO2 during the Calvin Cycle. D) The respiratory membrane provides a location to conduct the citric acid cycle.

B) The respiratory membrane allows a functional electron transport chain and oxidative phosphorylation of ATP.

Mycoplasmas are bacteria with the rare structural feature that they do not have cell walls. On the basis of this fact, 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 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.

What is one key difference between genetic transformation and transduction in prokaryotes? A) Transduction involves the uptake of foreign DNA from the surroundings, whereas transformation involves a virus transferring DNA from one bacterium to another. B) Transformation involves the uptake of foreign DNA from the surroundings, whereas transduction involves a virus transferring DNA from one bacterium to another. C) Transformation involves eukaryotes as the source of DNA, whereas transduction involves a transfer of DNA between bacteria. D) Transduction is the physical joining of one bacterium to another, whereas transformation is the uptake of DNA via a viral source.

B) Transformation involves the uptake of foreign DNA from the surroundings, whereas transduction involves a virus transferring DNA from one bacterium to another.

Which portion of a typical prokaryotic flagellum is embedded in the cell wall and plasma membrane? A) a hook B) a complex "motor" C) a filament D) a pili

B) a complex motor

Which of the following is a defining characteristic that all protocells or vesicles 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

Which pair of proteobacterial subgroups shown in the figure are most closely related through evolution? A) alpha and beta B) beta and gamma C) gamma and delta D) epsilon and beta

B) beta and gamma

The prokaryotic CRISPR-Cas system A) was discovered as a natural, evolutionarily derived immune system that arose in viruses as a defense mechanism to detect pathogenic bacteria. B) was discovered as a natural, evolutionarily derived immune system that arose in bacteria as a defense mechanism to viral infection. C) allows scientists to insert DNA into an organism but is limited to one group of gram-positive bacterial species. D) is an innovative approach that allows us to reduce our use of petroleum.

B) was discovered as a natural, evolutionarily derived immune system that arose in bacteria as a defense mechanism to viral infection.

Which of the following is likely the greatest impact that organisms have ever had on Earth? A) Early cyanobacteria released hydrogen to Earth's atmosphere during the water-splitting step of photosynthesis. B) Early cyanobacteria released carbon dioxide to Earth's atmosphere during the water-splitting step of photosynthesis. C) Early cyanobacteria released oxygen to Earth's atmosphere during the water-splitting step of photosynthesis. D) Early cyanobacteria released nitrogen to Earth's atmosphere during the water-splitting step of photosynthesis.

C) Early cyanobacteria released oxygen to Earth's atmosphere during the water-splitting step of photosynthesis.

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 challenging 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?

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?

The thermoacidophile Sulfolobus acidocaldarius lacks peptidoglycan but still possesses a cell wall. What is likely to be true of this species? A) It is a bacterium with enzymes that can function above a pH of 7 and withstand high temperatures. B) It is an archaean that could inhabit hot springs with alkaline conditions. C) It is an archaean that could inhabit hydrothermal vents if the optimal pH of its enzymes lies below pH 7. D) It is likely a gram-positive bacterium that has the ability to cope with high acidity and temperatures.

C) It is an archaean that could inhabit hydrothermal vents if the optimal pH of its enzymes lies below pH 7.

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 lack of genetic variation. 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.

Which of the following is an accurate characteristic of bacterial cell walls? A) They are primarily made of chitin. B) They prevent cells from shrinking in hypertonic environments. C) They prevent cells from bursting in hypertonic environments. D) They have peptidoglycan only if they are gram-negative.

C) They prevent cells from bursting in hypertonic environments.

Suppose it were possible to conduct sophisticated microscopic and chemical analyses of microfossils found in 3.5-billion-year-old rock formations. Which of the following structures would be surprising to observe? A) RNA B) vesicles with a membrane C) a nucleus D) ribozymes

C) a nucleus

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) self-replicating RNA molecules. D) antibiotic resistant.

C) self-replicating RNA molecules.

Which of the following is the correct sequence of events in the origin of life? A) formation of protocells, synthesis of organic molecules, synthesis of organic macromolecules, formation of DNA-based genetic systems B) formation of protocells, synthesis of organic macromolecules, synthesis of organic molecules, formation of DNA-based genetic systems C) synthesis of organic molecules, synthesis of organic macromolecules, formation of protocells, formation of DNA-based genetic systems D) synthesis of organic molecules, synthesis of organic macromolecule, formation of DNA- based genetic systems, formation of protocells

C) synthesis of organic molecules, synthesis of organic macromolecules, formation of protocells, formation of DNA-based genetic systems

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.

In sexually reproducing lizards, recombination and meiosis result in offspring that have a variety of genetic material from both parents and high genetic diversity in the population. In contrast, what is one key way in which genetic diversity arises in non-sexually reproducing bacteria? A) Bacterial and archaeal cells are able to mutate their DNA in order to adapt to harmful environmental conditions or to resist antibiotics. B) Binary fission results in two bacterium cells with unique DNA. C) Prokaryotes can sometimes exchange DNA when subjected to harmful environmental conditions. D) Bacteria typically form populations with high numbers of individuals, and combined with rapid generation times, this may lead to a high rate of genetic mutations.

D) Bacteria typically form populations with high numbers of individuals, and combined with rapid generation times, this may lead to a high rate of genetic mutations.

The termite gut protist Mixotricha paradoxa has at least two kinds of bacteria attached to its outer surface. One bacterium is a spirochete that propels its protist 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? A) mutualism only B) mutualism and parasitism only C) parasitism and symbiosis only D) mutualism, symbiosis, and metabolic cooperation E) parasitism, symbiosis, and metabolic cooperation

D) mutualism, symbiosis, and metabolic cooperation

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? A) cell walls that have peptidoglycan B) cells that are hypotonic to conditions on the surface of the fish C) cells able to survive salt concentrations lower than 9% D) the presence of very large numbers of ion pumps in the plasma membrane

D) the presence of very large numbers of ion pumps in the plasma membrane

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 more proteins than eukaryotes. 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.

Which of the following processes is least associated with the others? A) horizontal gene transfer B) genetic recombination C) conjugation D) transformation E) binary fission

E) binary fission

IMG 9 - Which species in the table is most likely to be found both in sewage treatment plants and in the guts of cattle?

Spec B

IMG 9 -Which species in the table is probably an important contributor of organic compounds such as sugars, which are then passed up through aquatic food chains?

Spec E

IMG 9 - In the table, Species D is pathogenic if it gains access to the human intestine. Which other species, if it co-inhabited 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?

Species 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 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.This bacterium derives nutrition by digesting human intestinal contents (in other words, food). Thus, this bacterium should be an

anaerobic chemoheterotroph.

The following question(s) are based on the observation that several dozen different proteins comprise the prokaryotic flagellum and its attachment to the prokaryotic cell, producing a highly complex structure.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

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

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." 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?

be obligate anaerobes and package these enzymes in specialized cells or compartments that inhibit oxygen entry

IMG 11 - What is occurring at time C that is decreasing the DNA content?

degradation of DNA that was not retained in the recipient's chromosome

IMG 11- During which two times can the recipient accurately be described as "recombinant" due to the sequence of events portrayed in the figure?

during times C and D

IMG 10 If the vertical axis of the figure refers to "Darwinian fitness," then which of the following is the most valid and accurate measure of fitness?

number of offspring or close kin that survive to reproductive age Submit

On early Earth, what substance is hypothesized to have played a key role to facilitate the formation of polymers of amino acids, polymers of RNA, and vesicles? A) DNA B) sand, rock, or clay C) peptidoglycan D) biofilms

sand, rock, or clay

Which two species in the table might be expected to cooperate metabolically, perhaps forming a biofilm wherein one species surrounds cells of the other species?

species A and B

IMG 9: Which two species in the table should have much more phospholipid, in the form of bilayers, in their cytoplasm than most other bacteria?

species B and E

IMG 9: Which species in the table should be able to respond most readily to taxes (plural of taxis)?

species C

IMG 9 : Which species in the table is most self-sustaining in terms of obtaining nutrition in environments containing little fixed nitrogen or carbon?

species E

... 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

structures originally adapted for one purpose can take on new functions through descent with modification.

In a hypothetical situation, assume that 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

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

IMG 9: How many of these species in the table probably have a cell wall that partly consists of an outer membrane of lipopolysaccharide?

three species

IMG 10 - If the experimental population of E. coli lacks an F factor or F plasmid, and if bacteriophages are excluded from the bacterial cultures, then which of these is means by which beneficial mutations might be transmitted horizontally to other E. coli cells?

via transformation