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Chapter 27
Multiple Choice
Identify the choice that best completes the statement or answers the question.
____
1. Which is the bacterial structure that acts as a selective barrier, allowing nutrients to enter the cell and
wastes to leave the cell?
a. plasma membrane
b. capsule
c. cell wall
d. nucleoid region
e. pili
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2. Jams, jellies, preserves, honey, and other foodstuffs with a high sugar content hardly ever become
contaminated by bacteria, even when the food containers are left open at room temperature. This is
because bacteria that encounter such an environment
a. undergo death by plasmolysis.
b. are unable to metabolize the glucose or fructose, and thus starve to death.
c. undergo death by lysis.
d. are obligate anaerobes.
e. are unable to swim through these thick and viscous materials.
____
3. 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.
The following questions refer to structures found in a gram-positive prokaryotic cell.
____
4. Which of the following is composed almost entirely of peptidoglycan?
a. endospore
b. sex pilus
c. flagellum
d. cell wall
e. capsule
____
5. Not present in all bacteria, this cell covering enables cells that possess it to resist the defenses of host
organisms:
a. endospore
b. sex pilus
c. flagellum
d. cell wall
e. capsule
____
6. Not present in all bacteria, this structure enables those that possess it to germinate after exposure to
harsh conditions, such as boiling:
a. endospore
b.
c.
d.
e.
____
sex pilus
flagellum
cell wall
capsule
7. Regarding prokaryotic reproduction, which statement is correct?
a. Prokaryotes form gametes by meiosis.
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.
____
8. Which of these statements about prokaryotes is correct?
a. Bacterial cells conjugate to mutually exchange genetic material.
b. Their genetic material is confined within a nuclear envelope.
c. They divide by binary fission, without mitosis or meiosis.
d. The persistence of bacteria throughout evolutionary time is due to their genetic
homogeneity (i.e., sameness).
e. Genetic variation in bacteria is not known to occur, nor should it occur, because of
their asexual mode of reproduction.
The following questions refer to Figure 27.1 below, which is the same as Figure 27.10 in the
textbook.
In this 8-year experiment, 12 populations of E. 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 lowglucose conditions was tested against that of members sampled from the ancestral (common
ancestor) E. coli population.
Figure 27.1
____
9. If it occurs in the absence of any other type of adaptation listed here, which of these is least
reasonable in terms of promoting bacterial survival over evolutionary time in a low-glucose
environment?
a.
b.
c.
d.
e.
increased efficiency at transporting glucose into the cell from the environment
increased ability to survive on simple sugars, other than glucose
increased ability to synthesize glucose from amino acid precursors
increased reliance on glycolytic enzymes
increased sensitivity to, and ability to move toward, whatever glucose is present in
its habitat
____ 10. Which of these can be inferred from Figure 27.1?
a. Most of the genetic change that permitted adaptation to the new, low-glucose
environment occurred toward the conclusion of the experiment.
b. Rates of mitosis increased over the course of the experiment.
c. The highest rate of genetic change occurred during the first quarter of the
experiment.
d. After 5,000 generations, the bacteria were 100% more fit than the original,
ancestral bacteria.
____ 11. If the vertical axis of Figure 27.1 refers to "Darwinian fitness," then which of these is the most valid
and accurate measure of fitness?
a. number of daughter cells produced per mother cell per generation
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
____ 12. 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.
Figure 27.2 depicts changes to the amount of DNA present in a recipient cell that is engaged in
conjugation with an Hfr cell. Hfr-cell DNA begins entering the recipient cell at Time A. Assume that
reciprocal crossing-over occurs (i.e., a fragment of the recipient's chromosome is exchanged for a
homologous fragment from the Hfr cell's DNA). Use Figure 27.2 to answer the following questions.
Figure 27.2
____ 13. 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
Match the numbered terms to the descriptions that follow. For each item, choose all appropriate
terms, but only appropriate terms.
1. autotroph
2. heterotroph
3. phototroph
4. chemotroph
____ 14. 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
____ 15. Which of the following are responsible for many human diseases?
a. photoautotrophs
b. photoheterotrophs
c. chemoautotrophs
d. chemoheterotrophs that perform decomposition
e. parasitic chemoheterotrophs
____ 16. Which of the following use light energy to generate ATP, but do not release oxygen?
a. photoautotrophs
b. photoheterotrophs
c. chemoautotrophs
d. chemoheterotrophs that perform decomposition
e. parasitic chemoheterotrophs
____ 17. Which of the following are responsible for high levels of O2 in Earth's atmosphere?
a. photoautotrophs
b. photoheterotrophs
c. chemoautotrophs
d. chemoheterotrophs that perform decomposition
e. parasitic chemoheterotrophs
____ 18. The data were collected from the heterocytes of a nitrogen-fixing cyanobacterium inhabiting
equatorial ponds. Study the graph below and choose the most likely explanation for the shape of the
curve.
a. Enough O2 enters heterocytes during hours of peak photosynthesis to have a
somewhat-inhibitory affect 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 are not absorbing this gas through their stomata.
d. Heterocyte walls become less permeable to N2 influx during darkness.
e. The amount of fixed nitrogen that is dissolved in the pond water in which the
cyanobacteria are growing peaks at the close of the photosynthetic day (1800 h).
____ 19. 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
____ 20. Which statement about the domain Archaea is false?
a. Genetic prospecting has recently revealed the existence of many previously
b.
c.
d.
e.
unknown archean species.
Some archaeans can reduce CO2 to methane.
The genomes of archaeans are unique, containing no genes that originated within
bacteria.
Some archaeans can inhabit solutions that are nearly 30% salt.
Some archaeans are adapted to waters with temperatures above the boiling point.
____ 21. Consider the thermoacidophile, Sulfolobus acidocaldarius. Which graph 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.
____ 22. 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, it causes a fatal disease in the plant.
Once the plant dies, the bacterium and its offspring decompose the plant. What is the correct
sequence of ecological roles played by the bacterium in the situation described here? Use only those
that apply.
1. nutrient recycler
2. mutualist
3. commensal
4. parasite
5. primary producer
a. 1, 3, 4
b. 2, 3, 4
c. 2, 4, 1
d. 1, 2, 5
e. 1, 2, 3
____ 23. How can prokaryotes be considered to be more successful on Earth than humans?
a. Prokaryotes are much more numerous and have more biomass.
b. Prokaryotes occupy more diverse habitats.
c. Prokaryotes are more diverse in metabolism.
d. Only B and C are correct.
e. A, B, and C are correct.
____ 24. 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.
____ 25. Which prokaryotic group is mismatched with its members?
a. Proteobacteria–diverse gram-negative bacteria
b. Gram-positive bacteria–symbionts in legume root nodules
c. Spirochetes–helical heterotrophs
d. Chlamydias–intracellular parasites
e. Cyanobacteria–solitary and colonial photoautotrophs
Chapter 27
Answer Section
MULTIPLE CHOICE
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A
PTS: 1
Knowledge/Comprehension
A
PTS: 1
Application/Analysis
C
PTS: 1
Knowledge/Comprehension
D
PTS: 1
Knowledge/Comprehension
E
PTS: 1
Knowledge/Comprehension
A
PTS: 1
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D
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C
PTS: 1
Knowledge/Comprehension
D
PTS: 1
Application/Analysis
C
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Application/Analysis
E
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Synthesis/Evaluation
C
PTS: 1
Application/Analysis
D
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Knowledge/Comprehension
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Synthesis/Evaluation
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Application/Analysis
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TOP: Concept 27.1
TOP: Concept 27.1
TOP: Concept 27.1
TOP: Concept 27.1
TOP: Concept 27.1
TOP: Concept 27.1
TOP: Concept 27.2
TOP: Concept 27.2
TOP: Concept 27.2
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TOP: Concept 27.2
TOP: Concept 27.2
TOP: Concept 27.2
TOP: Concept 27.3
TOP: Concept 27.3
TOP: Concept 27.3
TOP: Concept 27.3
TOP: Concept 27.3
TOP: Concept 27.4
TOP: Concept 27.4
TOP: Concept 27.4
TOP: Concept 27.5
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25. ANS:
Application/Analysis
E
PTS: 1
Knowledge/Comprehension
D
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B
PTS: 1
TOP: Concept 27.5
TOP: Self-Quiz Questions
TOP: Self-Quiz Questions