Deck 24: Early Life and the Diversification of Prokaryotes

Question 1

Suppose it were possible to conduct sophisticated microscopic and chemical analyses of microfossils found in 3.5-billion-year-old stromatolites. Which of the following structures would be surprising to observe?
I) RNA
II) vesicles
III) a nucleus
IV) ribozymes

A) I
B) II
C) III
D) IV

Answer 1

C

Question 2

The typical prokaryotic flagellum features

A) an external covering provided by the plasma membrane.
B) a complex "motor" embedded in the cell wall and plasma membrane.
C) a basal body that is similar in structure to the cell's centrioles.
D) a membrane-enclosed organelle with motor proteins.

Answer 2

B

Question 3

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.

Answer 3

C

Question 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

Question 5

Which of the following is an accurate characteristic of bacterial cell walls?

A) They are primarily made of chitin.
B) They prevent cells from bursting in hypertonic environments.
C) They prevent cells from bursting in hypotonic conditions.
D) They only have peptidoglycan if they are gram-negative.

Question 6

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?

Question 7

Scientists hypothesize that prokaryotes evolved before 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.

Question 8

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

Question 9

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 chromosomes.
D) lack water in its cytoplasm.
E) be unable to survive in its normal environment.

Question 10

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.

Question 11

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.

Question 12

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

Question 13

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

Question 14

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.

Question 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

Question 16

The first genetic material on early Earth was most likely

A) DNA.
B) RNA.
C) peptidoglycan.
D) protocells.

Question 17

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.

Question 18

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.

Question 19

The predatory bacterium Bdellovibrio bacteriovorus 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. bacteriovorus 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

Question 20

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

Question 21

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

Question 22

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.

Question 23

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?

Question 24

Prokaryotes' essential genetic information is located in the

A) flagella.
B) nucleoid.
C) capsule.
D) plasmids.
E) endospore.

Question 25

Why can prokaryotic populations be magnitudes larger than populations of multicellular eukaryotes?
I) Prokaryotes are small.
II) Prokaryotes reproduce by binary fission.
III) Prokaryotes often have short generation times.
IV) Prokaryotes have cells walls primarily made of cellulose.

A) I only
B) I and III
C) II, III, IV
D) I, II, III

Question 26

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

Question 27

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.

Question 28

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

Question 29

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

Question 30

Which of the following oxidizes inorganic substances to obtain energy that is used, in part, to fix CO₂?

A) photoautotrophs
B) photoheterotrophs
C) chemoautotrophs
D) chemoheterotrophs that perform decomposition

Question 31

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

Question 32

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.

Question 33

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.

Question 34

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.

Question 35

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.

Question 36

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.

Question 37

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

Question 38

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

Question 39

Which of the following is least associated with the others?

A) horizontal gene transfer
B) genetic recombination
C) conjugation
D) transformation
E) binary fission

Question 40

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

Question 41

Please use the following information to answer the question(s) below.
In Figure 24.1, data are presented from an eight-year experiment in which 12 populations of Escherichia coli, each begun from a single cell, were grown in low-glucose conditions for 20,000 generations. Each culture was introduced to fresh growth medium every 24 hours. Occasionally, samples were removed from the populations, and their fitness in low-glucose conditions was tested against that of members sampled from the ancestral (common ancestor) E. coli population. Figure 24.1
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

A) transduction.
B) binary fission.
C) conjugation.
D) transformation.
E) meiosis.

Question 42

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

Question 43

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 lies above pH 7.
4) The optimal pH of its enzymes lies 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

Question 44

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?

A)
B)
C)
D)

Question 45

Figure 24.2 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 24.2 to answer the following question(s). Figure 24.2
How is the recipient cell different at time D than it was at time A?

A) It has a greater number of genes.
B) It has a greater mass of DNA.
C) It has a different sequence of base pairs.
D) It contains bacteriophage DNA.
E) Its membrane-bound DNA pumps are inactive.

Question 46

Figure 24.2 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 24.2 to answer the following question(s). Figure 24.2
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

A) 1 and 2
B) 1 and 3
C) 2 and 3
D) 2 and 4
E) 3 and 4

Question 47

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.

Question 48

Figure 24.2 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 24.2 to answer the following question(s). Figure 24.2
Which question arising from the results depicted in Figure 24.2 is most interesting from a genetic perspective and has the greatest potential to increase our knowledge base?

A) 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?
B) What forces are generally responsible for disrupting the sex pilus?
C) How is it that a recipient cell does not necessarily become an Hfr cell as the result of conjugation with an Hfr cell?
D) What makes a cell an Hfr cell?

Question 49

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

Question 50

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

Question 51

Please use the following information to answer the question(s) below.
In Figure 24.1, data are presented from an eight-year experiment in which 12 populations of Escherichia coli, each begun from a single cell, were grown in low-glucose conditions for 20,000 generations. Each culture was introduced to fresh growth medium every 24 hours. Occasionally, samples were removed from the populations, and their fitness in low-glucose conditions was tested against that of members sampled from the ancestral (common ancestor) E. coli population. Figure 24.1
If the vertical axis of Figure 24.1 refers to "Darwinian fitness," then which of the following is the most valid and accurate measure of fitness?

A) number of offspring or close kin that survive to reproductive age
B) amount of ATP generated per cell per unit time
C) average swimming speed of cells through the growth medium
D) amount of glucose synthesized per unit time
E) number of generations per unit time

Question 52

What is a main difference between endotoxins and exotoxins?

A) Endotoxins are proteins and exotoxins are lipopolysaccharides.
B) Endotoxins are lipopolysaccharides and exotoxins are proteins.
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.

Question 53

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 contain less cellulose than do bacteria that possess cell walls.
E) They possess typical prokaryotic flagella.

Question 54

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 the 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

Question 55

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.

Question 56

Figure 24.2 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 24.2 to answer the following question(s). Figure 24.2
What is occurring at time C that is decreasing the DNA content?

A) crossing over
B) cytokinesis
C) meiosis
D) degradation of DNA that was not retained in the recipient's chromosome
E) reversal of the direction of conjugation

Question 57

Please use the following information to answer the question(s) below.
In Figure 24.1, data are presented from an eight-year experiment in which 12 populations of Escherichia coli, each begun from a single cell, were grown in low-glucose conditions for 20,000 generations. Each culture was introduced to fresh growth medium every 24 hours. Occasionally, samples were removed from the populations, and their fitness in low-glucose conditions was tested against that of members sampled from the ancestral (common ancestor) E. coli population. Figure 24.1
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?

A) via sex pili
B) via transduction
C) via conjugation
D) via transformation

Question 58

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

Question 59

Please use the following information to answer the question(s) below.
In Figure 24.1, data are presented from an eight-year experiment in which 12 populations of Escherichia coli, each begun from a single cell, were grown in low-glucose conditions for 20,000 generations. Each culture was introduced to fresh growth medium every 24 hours. Occasionally, samples were removed from the populations, and their fitness in low-glucose conditions was tested against that of members sampled from the ancestral (common ancestor) E. coli population. Figure 24.1
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)?

A) Generation time should be the same as in the typical environment.
B) Generation time should be faster than in the typical environment.
C) Generation time should be slower than in the typical environment.
D) It is theoretically impossible to make any predictions about generation time under these conditions.

Question 60

Figure 24.2 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 24.2 to answer the following question(s). Figure 24.2
During which two times can the recipient accurately be described as "recombinant" due to the sequence of events portrayed in Figure 24.2?

A) during times C and D
B) during times A and C
C) during times B and C
D) during times A and B
E) during times B and D

Question 61

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.
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

A) 1 or 4
B) 1 or 3
C) 2 or 4
D) 3 or 4

Question 62

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

A) 4 only
B) 1 and 3
C) 2 and 3
D) 3 and 4
E) 2, 3, and 4

Question 63

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.
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

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

Question 64

Please use the following information to answer the question(s) below.
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?
1) package them in membranes that are impermeable to all gases
2) be obligate anaerobes
3) be facultative aerobes
4) package these enzymes in specialized cells or compartments that inhibit oxygen entry

A) 1 and 4
B) 2 and 4
C) 2 and 3
D) 3 and 4

Question 65

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.
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

A) 1 only
B) 2 only
C) 3 only
D) 2 and 3

Question 66

The table depicts characteristics of five prokaryotic species (A-E). Use the information in the table to answer the following question(s). Table 24.1
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

Question 67

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.
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.

Question 68

The table depicts characteristics of five prokaryotic species (A-E). Use the information in the table to answer the following question(s). Table 24.1
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

Question 69

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?

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.

Question 70

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.)

A)
B)
C)
D)

Question 71

The table depicts characteristics of five prokaryotic species (A-E). Use the information in the table to answer the following question(s). Table 24.1
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

Question 72

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

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.

Question 73

The table depicts characteristics of five prokaryotic species (A-E). Use the information in the table to answer the following question(s). Table 24.1
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

Question 74

The table depicts characteristics of five prokaryotic species (A-E). Use the information in the table to answer the following question(s). Table 24.1
Which two species should have much more phospholipid, in the form of bilayers, in their cytoplasm 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

Question 75

The table depicts characteristics of five prokaryotic species (A-E). Use the information in the table to answer the following question(s). Table 24.1
Which species is probably an important contributor of organic compounds such as sugars, which are then passed up through aquatic food chains?

A) species A
B) species B
C) species C
D) species D
E) species E

Question 76

The table depicts characteristics of five prokaryotic species (A-E). Use the information in the table to answer the following question(s). Table 24.1
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

Question 77

Figure 24.2 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 24.2 to answer the following question(s). Figure 24.2
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. Figure 24.3

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 metabolizing this gas, so they are not absorbing this gas through their stomata.
D) Heterocyst walls become less permeable to N2 influx during darkness.

Question 78

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.
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.

Question 79

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.
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) structures originally adapted for one purpose can take on new functions through descent with modification.
E) bacteria that possess flagella must have lost the ability to pump certain chemicals across their plasma membranes.

Question 80

The table depicts characteristics of five prokaryotic species (A-E). Use the information in the table to answer the following question(s). Table 24.1
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