1) Mycoplasmas are bacteria that lack cell walls. On the
basis of this structural feature, which statement concerning mycoplasmas should
be true?
A) They are gram-negative.
B) They are subject to lysis in hypotonic conditions.
C) They lack a cell membrane as well.
D) They should contain less cellulose than do bacteria
that possess cell walls.
E) They possess typical prokaryotic flagella.
Answer: B
2) Though plants, fungi, and prokaryotes all have cell
walls, we place them in different taxa. Which of these observations comes
closest to explaining the basis for placing these organisms in different taxa,
well before relevant data from molecular systematics became available?
A) Some closely resemble animals, which lack cell walls.
B) Their cell walls are composed of very different
biochemicals.
C) Some have cell walls only for support.
D) Some have cell walls only for protection from
herbivores.
E) Some have cell walls only to control osmotic balance.
Answer: B
3) Which statement about bacterial cell walls is false?
A) Bacterial cell walls differ in molecular composition
from plant cell walls.
B) Cell walls prevent cells from bursting in hypotonic
environments.
C) Cell walls prevent cells from dying in hypertonic
conditions.
D) Bacterial cell walls are similar in function to the
cell walls of many protists, fungi, and plants.
E) Cell walls provide the cell with a degree of physical
protection from the environment.
Answer: C
4) The predatory bacterium, Bdellovibrio bacteriophorus,
drills into a prey bacterium and, once inside, digests it. In an attack upon a
gram-negative bacterium that has a slimy cell covering, what is the correct
sequence of structures penetrated by B. bacteriophorus on its way to the prey's
cytoplasm?
1. membrane composed mostly of lipopolysaccharide
2. membrane composed mostly of phospholipids
3. peptidoglycan
4. capsule
A) 2, 4, 3, 1
B) 1, 3, 4, 2
C) 1, 4, 3, 2
D) 4, 1, 3, 2
E) 4, 3, 1, 2
Answer: D
5) Jams, jellies, preserves, honey, and other foodstuffs
with high sugar content hardly ever become contaminated by bacteria, even when
the food containers are left open at room temperature. This is because bacteria
that encounter such an environment
A) undergo death by plasmolysis.
B) are unable to metabolize the glucose or fructose, and
thus starve to death.
C) experience lysis.
D) are obligate anaerobes.
E) are unable to swim through these thick and viscous
materials.
Answer: A
6) In a bacterium that possesses antibiotic resistance
and the potential to persist through very adverse conditions, such as freezing,
drying, or high temperatures, DNA should be located within, or be part of,
which structures?
1. nucleoid region
2. endospore
3. fimbriae
4. plasmids
A) 1 only
B) 1 and 2 only
C) 1 and 4 only
D) 2 and 4 only
E) 1, 2, and 4
Answer: E
7) Which two structures play direct roles in permitting
bacteria to adhere to each other, or to other surfaces?
1. capsules
2. endospores
3. fimbriae
4. plasmids
5. flagella
A) 1 and 2
B) 1 and 3
C) 2 and 3
D) 3 and 4
E) 3 and 5
Answer: B
8) The typical prokaryotic flagellum features
A) an internal 9 + 2 pattern of microtubules.
B) an external covering provided by the plasma membrane.
C) a complex "motor" embedded in the cell wall
and plasma membrane.
D) a basal body that is similar in structure to the
cell's centrioles.
E) a membrane-enclosed organelle with motor proteins.
Answer: C
9) Prokaryotic ribosomes differ from those present in
eukaryotic cytosol. Because of this, which of the following is correct?
A) Some antibiotics can block protein synthesis in
bacteria without effects in the eukaryotic host.
B) Eukaryotes did not evolve from prokaryotes.
C) Translation can occur at the same time as
transcription in eukaryotes but not in prokaryotes.
D) Some antibiotics can block the synthesis of
peptidoglycan in the walls of bacteria.
E) Prokaryotes are able to use a much greater variety of
molecules as food sources than can eukaryotes.
Answer: A
10) Which statement about the genomes of prokaryotes is
correct?
A) Prokaryotic genomes are diploid throughout most of the
cell cycle.
B) Prokaryotic chromosomes are sometimes called plasmids.
C) Prokaryotic cells have multiple chromosomes,
"packed" with a relatively large amount of protein.
D) The prokaryotic chromosome is not contained within a
nucleus but, rather, is found at the nucleolus.
E) Prokaryotic genomes are composed of circular DNA.
Answer: E
11) If a bacterium regenerates from an endospore that did
not possess any of the plasmids that were contained in its original parent
cell, the regenerated bacterium will probably also
A) lack antibiotic-resistant genes.
B) lack a cell wall.
C) lack a chromosome.
D) lack water in its cytoplasm.
E) be unable to survive in its normal environment.
Answer: A
12) Although not present in all bacteria, this cell
covering often enables cells that possess it to resist the defenses of host
organisms, especially their phagocytic cells.
A) endospore
B) sex pilus
C) cell wall
D) capsule
Answer: D
13) Prokaryotes' essential genetic information is located
in the
A) nucleolus.
B) nucleoid.
C) nucleosome.
D) plasmids.
E) exospore.
Answer: B
14) Which of the following is an important source of
endotoxin in gram-negative species?
A) endospore
B) sex pilus
C) flagellum
D) cell wall
E) capsule
Answer: D
15) Chloramphenicol is an antibiotic that targets
prokaryotic (70S) ribosomes, but not eukaryotic (80S) ribosomes. Which of these
questions stems from this observation, plus an understanding of eukaryotic
origins?
A) Can chloramphenicol also be used to control human
diseases that are caused by archaeans?
B) Can chloramphenicol pass through the capsules
possessed by many cyanobacteria?
C) If chloramphenicol inhibits prokaryotic ribosomes,
should it not also inhibit mitochondrial ribosomes?
D) Why aren't prokaryotic ribosomes identical to
eukaryotic ribosomes?
E) How is translation affected in ribosomes that are
targeted by chloramphenicol?
Answer: C
16) In a hypothetical situation, the genes for sex pilus
construction and for tetracycline resistance are located together on the same
plasmid within a particular bacterium. If this bacterium readily performs
conjugation involving a copy of this plasmid, then the result should be
A) a bacterium that has undergone transduction.
B) the rapid spread of tetracycline resistance to other
bacteria in that habitat.
C) the subsequent loss of tetracycline resistance from
this bacterium.
D) the production of endospores among the bacterium's
progeny.
E) the temporary possession by this bacterium of a
completely diploid genome.
Answer: B
17) Regarding prokaryotic genetics, which statement is
correct?
A) Crossing over during prophase I introduces some
genetic variation.
B) Prokaryotes feature the union of haploid gametes, as
do eukaryotes.
C) Prokaryotes exchange some of their genes by
conjugation, the union of haploid gametes, and transduction.
D) Mutation is a primary source of variation in
prokaryote populations.
E) Prokaryotes skip sexual life cycles because their life
cycle is too short.
Answer: D
18) Which of these statements about prokaryotes is
correct?
A) Bacterial cells conjugate to mutually exchange genetic
material.
B) Their genetic material is confined within vesicles
known as plasmids.
C) They divide by binary fission, without mitosis or meiosis.
D) The persistence of bacteria throughout evolutionary
time is due to their genetic homogeneity (in other words, sameness).
E) Genetic variation in bacteria is not known to occur,
because of their asexual mode of reproduction.
Answer: C
19) Which of the following is least associated with the
others?
A) horizontal gene transfer
B) genetic recombination
C) conjugation
D) transformation
E) binary fission
Answer: E
20) In Fred Griffith's experiments, harmless R strain
pneumococcus became lethal S strain pneumococcus as the result of which of the
following?
1. horizontal gene transfer
2. transduction
3. conjugation
4. transformation
5. genetic recombination
A) 2 only
B) 4 only
C) 2 and 5
D) 1, 3, and 5
E) 1, 4, and 5
Answer: E
21) Hershey and Chase performed an elegant experiment
that convinced most biologists that DNA, rather than protein, was the genetic
material. This experiment subjected bacteria to the same gene transfer
mechanism as occurs in
A) transduction.
B) transformation.
C) conjugation.
D) binary fission.
E) endosymbiosis.
Answer: A
22) Match the numbered terms to the description that
follows. Choose all appropriate terms.
1. autotroph
2. heterotroph
3. phototroph
4. chemotroph
a prokaryote that obtains both energy and carbon as it
decomposes dead organisms
A) 1 only
B) 4 only
C) 1 and 3
D) 2 and 4
E) 1, 3, and 4
Answer: D
23) Match the numbered terms to the description that
follows. Choose all appropriate terms.
1. autotroph
2. heterotroph
3. phototroph
4. chemotroph
an organism that obtains both carbon and energy by
ingesting prey
A) 1 only
B) 4 only
C) 1 and 3
D) 2 and 4
E) 1, 3, and 4
Answer: D
24) Match the numbered terms to the description that
follows. Choose all appropriate terms.
1. autotroph
2. heterotroph
3. phototroph
4. chemotroph
an organism that relies on photons to excite electrons
within its membranes
A) 1 only
B) 3 only
C) 1 and 3
D) 2 and 4
E) 1, 3, and 4
Answer: B
25) Which of the following obtain energy by oxidizing
inorganic substancesenergy that is used, in part, to
fix CO₂?
A) photoautotrophs
B) photoheterotrophs
C) chemoautotrophs
D) chemoheterotrophs that perform decomposition
E) parasitic chemoheterotrophs
Answer: C
26) Mitochondria are thought to be the descendants of
certain alpha proteobacteria. They are, however, no longer able to lead
independent lives because most genes originally present on their chromosome
have moved to the nuclear genome. Which phenomenon accounts for the movement of
these genes?
A) plasmolysis
B) conjugation
C) translation
D) endocytosis
E) horizontal gene transfer
Answer: E
27) Carl Woese and collaborators identified two major
branches of prokaryotic evolution. What was the basis for dividing prokaryotes
into two domains?
A) microscopic examination of staining characteristics of
the cell wall
B) metabolic characteristics such as the production of
methane gas
C) metabolic characteristics such as chemoautotrophy and
photosynthesis
D) genetic characteristics such as ribosomal RNA
sequences
E) ecological characteristics such as the ability to
survive in extreme environments
Answer: D
28) Which statement about the domain Archaea is true?
A) Genetic prospecting has recently revealed the
existence of many previously unknown archaean species.
B) No archaeans can reduce CO₂ to methane.
C) The genomes of archaeans are unique, containing no
genes that originated within bacteria.
D) No archaeans can inhabit solutions that are nearly 30%
salt.
E) No archaeans are adapted to waters with temperatures
above the boiling point.
Answer: A
29) If archaeans are more closely related to eukaryotes
than to bacteria, then which of the following is a reasonable prediction?
A) Archaean DNA should have no introns.
B) Archaean chromosomes should have no protein bonded to
them.
C) Archaean DNA should be single-stranded.
D) Archaean ribosomes should be larger than typical
prokaryotic ribosomes.
E) Archaeans should lack cell walls.
Answer: D
30) Which of the following traits do archaeans and
bacteria share?
1. composition of the cell wall
2. presence of plasma membrane
3. lack of a nuclear envelope
4. identical rRNA sequences
A) 1 only
B) 3 only
C) 1 and 3
D) 2 and 3
E) 2 and 4
Answer: D
31) Assuming that each of these possesses a cell wall,
which prokaryotes should be expected to be most strongly resistant to plasmolysis
in hypertonic environments?
A) extreme halophiles
B) extreme thermophiles
C) methanogens
D) cyanobacteria
E) nitrogen-fixing bacteria that live in root nodules
Answer: A
32) The thermoacidophile, Sulfolobus acidocaldarius,
lacks peptidoglycan, but still possesses a cell wall. What is likely to be true
of this species?
1. It is a bacterium.
2. It is an archaean.
3. The optimal pH of its enzymes will lie above pH 7.
4. The optimal pH of its enzymes will lie below pH 7.
5. It could inhabit certain hydrothermal springs.
6. It could inhabit alkaline hot springs.
A) 1, 3, and 6
B) 2, 4, and 6
C) 2, 4, and 5
D) 1, 3, and 5
E) 1, 4, and 5
Answer: C
33) A fish that has been salt-cured subsequently develops
a reddish color. You suspect that the fish has been contaminated by the extreme
halophile, Halobacterium. Which of these features of cells removed from the
surface of the fish, if confirmed, would support your suspicion?
1. the presence of the same photosynthetic pigments found
in cyanobacteria
2. cell walls that lack peptidoglycan
3. cells that are isotonic to conditions on the surface
of the fish
4. cells containing bacteriorhodopsin
5. the presence of very large numbers of ion pumps in its
plasma membrane
A) 2 and 5
B) 3 and 4
C) 1, 4, and 5
D) 3, 4, and 5
E) 2, 3, 4, and 5
Answer: E
34) The termite gut protist, Mixotricha paradoxa, has at
least two kinds of bacteria attached to its outer surface. One kind is a
spirochete that propels its host through the termite gut. A second type of
bacteria synthesizes ATP, some of which is used by the spirochetes. The
locomotion provided by the spirochetes introduces the ATP-producing bacteria to
new food sources. Which term(s) is (are) applicable to the relationship between
the two kinds of bacteria?
1. mutualism
2. parasitism
3. symbiosis
4. metabolic cooperation
A) 1 only
B) 1 and 2
C) 2 and 3
D) 1, 3, and 4
E) 2, 3, and 4
Answer: D
35) In general, what is the primary ecological role of
prokaryotes?
A) parasitizing eukaryotes, thus causing diseases
B) breaking down organic matter
C) metabolizing materials in extreme environments
D) adding methane to the atmosphere
E) serving as primary producers in terrestrial
environments
Answer: B
36) If all prokaryotes on Earth suddenly vanished, which
of the following would be the most likely and most direct result?
A) The number of organisms on Earth would decrease by 1020%.
B) Human populations would thrive in the absence of
disease.
C) Bacteriophage numbers would dramatically increase.
D) The recycling of nutrients would be greatly reduced,
at least initially.
E) There would be no more pathogens on Earth.
Answer: D
37) In a hypothetical situation, a bacterium lives on the
surface of a leaf, where it obtains nutrition from the leaf's nonliving, waxy
covering while inhibiting the growth of other microbes that are plant
pathogens. If this bacterium gains access to the inside of a leaf, however, it
causes a fatal disease in the plant. Once the plant dies, the bacterium and its
offspring decompose the plant. What is the correct sequence of ecological roles
played by the bacterium in the situation described here? Use only those that apply.
1. nutrient recycler
2. mutualist
3. commensal
4.parasite
5. primary producer
A) 1, 3, 4
B) 2, 3, 4
C) 2, 4, 1
D) 1, 2, 5
E) 1, 2, 3
Answer: C
38) Foods can be preserved in many ways by slowing or
preventing bacterial growth. Which of these methods should be least effective
at inhibiting bacterial growth?
A) Refrigeration: slows bacterial metabolism and growth.
B) Closing previously opened containers: prevents more
bacteria from entering, and excludes O₂.
C) Pickling: creates a pH at which most bacterial enzymes
cannot function.
D) Canning in heavy sugar syrup: creates osmotic
conditions that remove water from most bacterial cells.
E) Irradiation: kills bacteria by mutating their DNA to
such an extent that their DNA-repair enzymes are overwhelmed.
Answer: B
39) Broad-spectrum antibiotics inhibit the growth of most
intestinal bacteria. Consequently, assuming that nothing is done to counter the
reduction of intestinal bacteria, a hospital patient who is receiving
broad-spectrum antibiotics is most likely to become
A) unable to fix carbon dioxide.
B) antibiotic resistant.
C) unable to fix nitrogen.
D) unable to synthesize peptidoglycan.
E) deficient in certain vitamins and nutrients.
Answer: E
40. The following question refer to Figure .
In this eight-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
low-glucose conditions was tested against that of members sampled from the
ancestral (common ancestor) E. coli population.
Which term best describes what has occurred among the
experimental populations of cells over this eight-year period?
A) microevolution
B) speciation
C) adaptive radiation
D) sexual selection
E) stabilizing selection
Answer: A
41, In this eight-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
low-glucose conditions was tested against that of members sampled from the
ancestral (common ancestor) E. coli population.
Which of the following, if it occurs in the absence
of any other type of adaptation listed here, is least reasonable in terms of
promoting bacterial survival over evolutionary time in a low-glucose
environment?
A) increased efficiency at transporting glucose into the
cell from the environment
B) increased ability to survive on simple sugars, other
than glucose
C) increased ability to synthesize glucose from amino
acid precursors
D) increased reliance on glycolytic enzymes
E) increased sensitivity to, and ability to move toward,
whatever glucose is present in its habitat
Answer: D
42. In this eight-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
low-glucose conditions was tested against that of members sampled from the
ancestral (common ancestor) E. coli population.
If the vertical axis of Figure 27.1 refers to
"Darwinian fitness," then which of the following 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
Answer: E
43. In this eight-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
low-glucose conditions was tested against that of members sampled from the
ancestral (common ancestor) E. coli population.
If new genetic variation in the experimental
populations arose solely by spontaneous mutations, then the most effective
process for subsequently increasing the prevalence of the beneficial mutations
in the population over the course of generations is
A) transduction.
B) binary fission.
C) conjugation.
D) transformation.
E) meiosis.
Answer: B
44. In this eight-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
low-glucose conditions was tested against that of members sampled from the
ancestral (common ancestor) E. coli population.
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.
Answer: C
45. In this eight-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
low-glucose conditions was tested against that of members sampled from the
ancestral (common ancestor) E. coli population.
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 (are) 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
E) Two of the responses above are correct.
Answer: D
46. 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 to answer the following question.
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
Answer: D
47. Figure 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 to answer the following question.
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.
Answer: C
48 Figure 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 to answer the following question.
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. activation of DNA pumps in plasma membrane
A) 1 and 2
B) 1 and 4
C) 2 and 3
D) 2 and 4
E) 3 and 4
Answer: C
49. Figure 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 to answer the following question.
During which two times can the recipient accurately be
described as "recombinant" due to the sequence of events portrayed in
Figure 27.2?
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
Answer: A
50. Figure 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 to answer the following question.
Which question, arising from the results depicted in
Figure 27.2, 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?
Answer: A
51) The data were collected from the heterocysts of a
nitrogen-fixing cyanobacterium inhabiting equatorial ponds.
Study the following
graph and choose the most likely explanation for the shape of the curve.
A) Enough O₂ enters heterocysts during hours of peak
photosynthesis to have a somewhat-inhibitory effect on nitrogen fixation.
B) Light-dependent reaction rates must be highest between
1800 hours and 0600 hours.
C) Atmospheric N₂ levels increase at night because plants
are no longer metabolizing this gas, so they are not absorbing this gas through
their stomata.
D) Heterocyst 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 hours).
Answer: A
52) Consider the thermoacidophile, Sulfolobus
acidocaldarius.
Which of the following graphs most accurately depicts the
expected temperature and pH profiles of its enzymes? (Note: The horizontal axes
of these graphs are double, with pH above and temperature below.)
A. A
B. B
C. C
D. D
Answer: A
53. A hypothetical bacterium swims among human intestinal
contents until it finds a suitable location on the intestinal lining. It
adheres to the intestinal lining using a feature that also protects it from
phagocytes, bacteriophages, and dehydration. Fecal matter from a human in whose
intestine this bacterium lives can spread the bacterium, even after being mixed
with water and boiled. The bacterium is not susceptible to the penicillin
family of antibiotics. It contains no plasmids and relatively little
peptidoglycan.
This bacterium's ability to survive in a human who is
taking penicillin pills may be due to the presence of
1. penicillin-resistance genes
2. a secretory system that removes penicillin from the
cell
3. a gram-positive cell wall
4. a gram-negative cell wall
5. an endospore
A) 1 or 5
B) 2 or 3
C) 4 or 5
D) 2, 3, or 5
E) 2, 4, or 5
Answer: D
54. A hypothetical bacterium swims among human intestinal
contents until it finds a suitable location on the intestinal lining. It
adheres to the intestinal lining using a feature that also protects it from
phagocytes, bacteriophages, and dehydration. Fecal matter from a human in whose
intestine this bacterium lives can spread the bacterium, even after being mixed
with water and boiled. The bacterium is not susceptible to the penicillin
family of antibiotics. It contains no plasmids and relatively little peptidoglycan.
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.
Answer: C
55. A hypothetical bacterium swims among human intestinal
contents until it finds a suitable location on the intestinal lining. It
adheres to the intestinal lining using a feature that also protects it from
phagocytes, bacteriophages, and dehydration. Fecal matter from a human in whose
intestine this bacterium lives can spread the bacterium, even after being mixed
with water and boiled. The bacterium is not susceptible to the penicillin
family of antibiotics. It contains no plasmids and relatively little
peptidoglycan.
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.
Answer: C
56. A hypothetical bacterium swims among human intestinal
contents until it finds a suitable location on the intestinal lining. It
adheres to the intestinal lining using a feature that also protects it from
phagocytes, bacteriophages, and dehydration. Fecal matter from a human in whose
intestine this bacterium lives can spread the bacterium, even after being mixed
with water and boiled. The bacterium is not susceptible to the penicillin
family of antibiotics. It contains no plasmids and relatively little peptidoglycan.
Some of the proteins that allow this bacterium to
swim are related (in an evolutionary sense) to proteins that
A) attach to the single chromosome.
B) act as restriction enzymes.
C) synthesize peptidoglycan for the cell wall.
D) move penicillin out of the cell.
E) comprise its ribosomes.
Answer: D
57. A hypothetical bacterium swims among human intestinal
contents until it finds a suitable location on the intestinal lining. It
adheres to the intestinal lining using a feature that also protects it from
phagocytes, bacteriophages, and dehydration. Fecal matter from a human in whose
intestine this bacterium lives can spread the bacterium, even after being mixed
with water and boiled. The bacterium is not susceptible to the penicillin
family of antibiotics. It contains no plasmids and relatively little
peptidoglycan.
In which feature(s) should one be able to locate a
complete chromosome of this bacterium?
1. nucleolus
2. prophage
3. endospore
4. nucleoid
A) 4 only
B) 1 and 3
C) 2 and 3
D) 3 and 4
E) 2, 3, and 4
Answer: D
58. A hypothetical bacterium swims among human intestinal
contents until it finds a suitable location on the intestinal lining. It
adheres to the intestinal lining using a feature that also protects it from
phagocytes, bacteriophages, and dehydration. Fecal matter from a human in whose
intestine this bacterium lives can spread the bacterium, even after being mixed
with water and boiled. The bacterium is not susceptible to the penicillin
family of antibiotics. It contains no plasmids and relatively little
peptidoglycan.
The cell also lacks F factors and F plasmids. Upon
its death, this bacterium should be able to participate in
A) conjugation.
B) transduction.
C) transformation.
D) Three of the responses above are correct.
E) Two of the responses above are correct.
Answer: C
59. A hypothetical bacterium swims among human intestinal
contents until it finds a suitable location on the intestinal lining. It
adheres to the intestinal lining using a feature that also protects it from
phagocytes, bacteriophages, and dehydration. Fecal matter from a human in whose
intestine this bacterium lives can spread the bacterium, even after being mixed
with water and boiled. The bacterium is not susceptible to the penicillin
family of antibiotics. It contains no plasmids and relatively little
peptidoglycan.
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.
Answer: C
60. A hypothetical bacterium swims among human intestinal
contents until it finds a suitable location on the intestinal lining. It adheres
to the intestinal lining using a feature that also protects it from phagocytes,
bacteriophages, and dehydration. Fecal matter from a human in whose intestine
this bacterium lives can spread the bacterium, even after being mixed with
water and boiled. The bacterium is not susceptible to the penicillin family of
antibiotics. It contains no plasmids and relatively little peptidoglycan.
This bacterium derives nutrition by digesting human
intestinal contents (in other words, food). Humans lacking this bacterium have
no measurable reproductive advantage or disadvantage relative to humans who
harbor this bacterium. Consequently, the bacterium can be properly described as
which of the following?
1. symbiont
2. endosymbiont
3. mutualist
4. commensal
A) 4 only
B) 1 and 2
C) 1 and 4
D) 2 and 3
E) 2 and 4
Answer: C
61. 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. couple them with photosystem II (the photosystem that
splits water molecules)
2. package them in membranes that are impermeable to all
gases
3. be obligate anaerobes
4. be strict aerobes
5. package these enzymes in specialized cells or
compartments that inhibit oxygen entry
A) 1 and 4
B) 2 and 4
C) 2 and 5
D) 3 and 4
E) 3 and 5
Answer: E
62. 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 two questions below arise from a careful
reading of this quotation, and are most important for understanding how N₂
enters heterocysts, and how O₂ is kept out of heterocysts?
- 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?
- If the cell walls of Anabaena's photosynthetic cells are permeable to O₂ and CO₂, are they also permeable to N₂?
- If the nuclei of the photosynthetic cells contain the genes that code for nitrogen fixation, how can these cells fail to perform nitrogen fixation?
- If the nuclei of the heterocysts contain the genes that code for photosynthesis, how can these cells fail to perform photosynthesis?
- If the cell walls of Anabaena's heterocysts are permeable to N₂, how is it that N₂ doesn't diffuse out of the heterocysts before it can be fixed?
- If the thick cell walls of the heterocysts exclude entry of oxygen gas, how is it that they don't also exclude the entry of nitrogen gas?
A) 1 and 3
B) 1 and 6
C) 2 and 5
D) 3 and 4
E) 4 and 6
Answer: B
63. The following table depicts characteristics of five
prokaryotic species (A—E). Use the information in the table to answer the
following question.
Which two species should have much more phospholipid,
in the form of bilayers, in their cytoplasms than most other bacteria?
A) species A and B
B) species A and C
C) species B and E
D) species C and D
E) species C and E
Answer: C
64. The following table depicts characteristics of five
prokaryotic species (A—E). Use the information in the table to answer the
following question.
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
Answer: C
65. The following table depicts characteristics of five
prokaryotic species (A—E). Use the information in the table to answer the
following question.
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
Answer: C
66. The following table depicts characteristics of five
prokaryotic species (A—E). Use the information in the table to answer the
following question.
Gram-variable prokaryotes are, sometimes, those
without any peptidoglycan. Which two species are most likely to be archaeans?
A) species A and B
B) species A and C
C) species B and E
D) species C and D
E) species C and E
Answer: A
67. The following table depicts characteristics of five
prokaryotic species (A—E). Use the
information in the table to answer the
following question
.
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
Answer: C
68. The following table depicts characteristics of five
prokaryotic species (A—E). Use the information in the table to answer the
following question.
Which species might be able to include Hfr cells?
A) species A
B) species B
C) species C
D) species D
E) species E
Answer: D
69. The following table depicts characteristics of five
prokaryotic species (A—E). Use the information in the table to answer the
following question.
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
Answer: E
70. The following table depicts characteristics of five
prokaryotic species (A—E). Use the information in the table to answer the
following question.
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
Answer: A
71. The following table depicts characteristics of five
prokaryotic species (A—E). Use the information in the table to answer the
following question.
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
Answer: B
72. The following table depicts characteristics of five
prokaryotic species (A—E). Use the information in the table to answer the
following question.
Which species is probably an important contributor to
the base of aquatic food chains as a primary producer?
A) species A
B) species B
C) species C
D) species D
E) species E
Answer: E
73) Genetic variation in bacterial populations cannot
result from
A) transduction.
B) transformation
C) conjugation
D) mutation.
E) meiosis.
Answer: E
74) Photoautotrophs use
A) light as an energy source and CO₂ as a carbon source.
B) light as an energy source and methane as a carbon
source.
C) N₂ as an energy source and CO₂ as a carbon source.
D) CO₂ as both an energy source and a carbon source.
E) H₂S as an energy source and CO₂ as a carbon source.
Answer: A
75) Which of the following statements is not true?
A) Archaea and bacteria have different membrane lipids.
B) Both archaea and bacteria generally lack
membrane-enclosed organelles.
C) The cell walls of archaea lack peptidoglycan.
D) Only bacteria have histones associated with DNA.
E) Only some archaea use CO₂ to oxidize H₂, releasing
methane.
Answer: D
76) Which of the following involves metabolic cooperation
among prokaryotic cells?
A) binary fission
B) endospore formation
C) endotoxin release
D) biofilms
E) photoautotrophy
Answer: D
77) Bacteria perform each of the following ecological
roles. Which role typically does not involve a symbiosis?
A) skin commensalist
B) decomposer
C) aggregates with methane-consuming archaea
D) gut mutualist
E) pathogen
Answer: B
78) Plantlike photosynthesis that releases O₂ occurs in
A) cyanobacteria.
B) chlamydias.
C) archaea.
D) actinomycetes.
E) chemoautotrophic bacteria.
Answer: A
TRY AGAIN
DETAIL
TRY AGAIN
MONERA
1. Air kaldu dalam tabung reaksi tertutup rapat,
dipanaskan pada suhu 600C. Setelah dibiarkan selama satu minggu, ternyata
timbul bakteri, bakteri tersebut berasal dari … .
A. air kaldu
B. spora
C. udara
D. daging
E. benda mati
2. Bakteri yang dapat mengikat N2 dari udara untuk
membantu kesuburan tanah adalah … .
A. Mikrobacter & Escherchia
B. Azotobacter & Escherchia
C. Mycobacterium & Clostridium
D. Clastridium & Rhyzobium
E. Mycobacterium & Azotobacter
3. Bakteri patogen ini menyebabkan penyakit tertentu,
yaitu … .
A. Trieponema pallidium penyebab penyakit tipus
B. Diplococcus pneumoniac penyebab penyakit disentri
C. Vibrio comma penyebab penyakit kolera
D. Clostridium gonorrhoeae penyebab penyakit sipilis
E. Pasteurella pestis penyebab penyakit kusta / lepra
4. Persamaan antara bakteri dan alga biru (Cyanophyta)
antara lain ialah bahwa kedua duanya .
A. membentuk hifa
B. inti tak berdinding
C. mengandung fikosianin
D. hidup berkoloni
E. hidup autotrof
5. Peranan Cyanophyta dalam ekosistem antara lain sebagai
pioner sebab … .
A. sebagai sumber makanan bagi organisme
B. dapat hidup di tempat yang tidak menguntungkan
C. dapat hidup di tempat yang gersang
D. dapat mengubah lingkungan sehingga organisme lain
dapat hidup
E. merupakan tumbuhan kecil yang berhijau daun
6. Penyakit berbahaya yang disebabkan oleh bakteri
vibrion adalah … .
A. tifus
B. kolera
C. disentri
D. radang tenggorokan
E. radang paru-paru
7. Bakteri yang dapat hidup dan berkembang biak pada
medium yang mengandung zat-zat anorganik serta dapat mengoksidasi senyawa
amoniak dan menghasilkan energi adalah … .
A. Clostiridium
B. Mycobacterium
C. Nitrosococus
D. Azotobacter
E. Neisseria
8. Makhluk hidup yang dapat mengurai sampah organik yang
berasal dari tumbuhan mati dan bangkai ialah:
A. bakteri dan jamur
B. bakteri dan ganggang
C. ganggang dan rayap
D. ganggang dan cacing tanah
E. cacing tanah dan ulat
9. Bakteri yang berbentuk seperti koma dan membentuk bulu
cambuk disebut:
A. basilus
B. kokus
C. spiril
D. vibrion
E. streptokokus
10. Penyakit berbahaya yang disebabkan oleh bakteri
vibrion adalah … .
A. tifus
B. kolera
C. disentri
D. radang tenggorokan
E. radang paru-paru
11. Perkembangbiakan secara aseksual yang terjadi pada
ganggang hijau-biru berlangsung melalui:
A. spora, pembelahan biner, konyugasi
B. heterocyst, spora dan fragmentasi
C. pembelahan biner, spora, hormogonium
D. arthroposa, konyugasi, hormogonium
E. fragmentasi, heterocyst, isogami
12. Bakteri kemoautotrof dapat mensintesis CO2 menjadi
makanan dengan adanya … .
A. proses fisika
B. proses kimia
C. proses respirasi
D. bantuan matahari
E. tenaganya sendiri
13. Bakteri nitrogen yang menguraikan senyawa nitrat
menjadi amonia adalah … .
A. Nitrobacter
B. Nitrosococcus
C. Clostiridium botolimum
D. Clostiridium perfiranges
E. Clostiridium desulfucaris
14. Bakteri Rhizobium yang dapat bersimbiosis dengan
tanaman polong-polongan bermanfaat karena:
A. menghaluskan partikel-partikel tanah
B. memfiksasi nitrogen bebas menjadi nitrat yang
digunakan untuk pertumbuhan tanaman inangnya
C. memecah senyawa anorganik menjadi senyawa organik
D. memfiksasi nitrat menjadi nitrogem bebas
E. memecah senyawa organik menjadi senyawa anorganik
15. Pembentukan asam cuka oleh bakteri-bakteri asam cuka
disebabkan oleh pengaruh:
A. karbondioksida
B. oksigen
C. alkohol
D. asam
E. basa
16. Bakteri denitrifikasi tumbuh subur di tanah yang:
A. gembur, penuh bahan organik
B. liat, penuh bahan organik
C. gembur, penuh bahan organik
D. liat, penuh bahan anorganik
E. liat, gembur, penuh bahan anorganik
17. Bakteri yang dapat hidup dan berkembang biak pada
medium yang mengandung zat-zat anorganik serta dapat mengoksidasi senyawa
amoniak dan menghasilkan energi adalah … .
A. Clostiridium
B. Mycobacterium
C. Nitrosococus
D. Azotobacter
E. Neisseria
18. Peranan ganggang hijau-biru dalam ekosistem antara
lain sebagai vegetasi perintis, sebab:
A. sebagai sumber makanan bagi makhluk hidup
B. dapat hidup di tempat yang tidak menguntungkan
C. dapat hidup di tempat kering
D. dapat mengubah lingkungan sehingga organisme lain
dapat hidup
E. merupakan tumbuhan kecil yang mempunyai pigmen
hijau-biru
19. Pigmen yang dikandung ganggang hijau-biru adalah … .
A. fikosianin
B. fikobilin
C. fikoeritrin
D. antosianin
E. sitokrom
20. Ganggang hijau-biru yang hidup dalam organisme lain
disebut … .
A. sporofil
B. saprofit
C. parasit
D. endofit
E. ektofit
21. Perhatikan macam-macam penyakit di bawah ini:
1. Tipus
2. Trachom
3. Kolera
4. Rabies
5. Sipilis
6. Demam berdarah
Penyakit yang disebabkan oleh bakteri adalah …
A. 1 – 2 – 3
B. 2 – 3 – 4
C. 3 – 4 – 5
D. 1 – 3 – 5
E. 1 – 5 – 6
22. Bakteri yang berperanan untuk pembuatan nata de coco
adalah … .
A. Lactobacilus casei
B. Acetobacter xylinum
C. Streptococcus griceus
D. Pseudomonas cocovenenan
E. Borditella pertusie
23. Jenis Alga biru yang hidup bersimbiosis dengan
tumbuhan tinggi dan sangat menguntungkan karena mengikat N2 bebas dari udara
adalah … .
A. Rhyzobium
B. Anabaena
C. Rivularia
D. Nostoc
E. Azotobacter
24. Bakteri dan ganggang biru dimasukkan ke dalam
golongan Monera, atas dasar … .
A. ukuran selnya
B. selaput intinya
C. cara reproduksinya
D. bentuk organella selnya
E. struktur dinding selnya
25. Beberapa bukti yang menunjukkan bahwa sel eukariot
berasal dari sel prokariot adalah ...
a. berdasarkan bentuk-bentuk fosil yang ditemukan
b. berdasarkan bukti-bukti yang ditunjukkan oleh teori Infolding
dan endosimbiotik
c. sel eukariot masih memiliki komponen sel prokariot
d. sel eukariot memiliki habitat yang sama dengan
prokariot
e. ukuran sel eukariot yang lebih besar dibandingkan
prokariot
26. Berapa lama waktu yang dibutuhkan oleh sel prokaryot
berevolusi menjadi sel eukariot?
a. tidak ada batasan waktu
b. 1 antara 1 - 1,5 milyar tahun
c. setara dengan masa hidup sel prokariot
d. Sepanjang waktu sel membelah
e. tergantung pada habitat. prokariot yang hidup di
daerah ekstrim lebih cepat berubah menjadi eukariot
27. Pernyataan tentang teori Infolding adalah ...
a. proses pembentukkan membran nukleus pada sel prokariot
b. proses penggandaan kromosom sirkuler pada sel eukariot
c. proses invaginasi dari membran sel untuk membentuk
organel-organel sel pada sel prokaryot
d. proses pembentukkan flagel dan filli untuk mempercepat
gerakan sel
e. Penebalan dinding sel prokariot dalam upaya mengatasi
lingkungan yang buruk
28. Dua jenis organel sel yang terbentuk menurut teori
endosymbiotik adalah ...
a. ribosom dan mesosom
b. kloroplast dan sitoplasma
c. retikulum endoplasma dan badan golgi
d. sentrosom dan mitokondria
e. kloroplas dan mitokondria
29. Reproduksi seksual bakteri yang dilakukan dengan cara
pertukaran materi genetik dengan bantuan virus disebut ...
a. pembelahan biner
b. transeksual
c. transduksi
d. konjugasi
e. transformasi
30. Fungsi filli saat pada reproduksi konjugasi?
a. alat untuk melekat pada bakteri lain
b. sebagai benang penghubung untuk menukarkan materi
genetik
c. alat untuk mengeluarkan materi genetik
d. alat untuk membentuk subtansi genetika baru
e. alat untuk mentransfer materi genetik
31. Bahan dasar pembentuk struktur dinding sel bakteri adalah ...
a. lipoprotein
b. semipermeabel
c. lendir
d. peptidoglikan
e. lemak
32. Struktur organel sel dibawah ini yang tidak pernah
dijumpai pada sel prokaryot adalah ...
a. plasmid
b. mitokondria
c. ribosom
d. dinding sel
e. membran plasma
33. Makhluk hidup yang termasuk prokariot dan memiliki
jumlah paling besar adalah ...
a. Eubakteri
b. archaebacteria
c. cyanobacteria
d. protozoa
e. ganggang
34. organisme yang termasuk kelompok prokaryot adalah ...
a. protozoa, jamur dan alga
b. protozoa, alga biru dan bakteri
c. protozoa, virus, dan monera
d. protozoa, virus dan cyanobacteria
e. Eubacteria, cyanobacteria dan archaebacteria
35. Prokaryot yang hidup di daerah ekstrim adalah ...
a. Archaebacteria
b. eubacteria
c. cyanobacteria
d. klorophyta
e. protozoa
36. Prokaryot yang mengambil bahan anorganik dan
merubahnya menjadi bahan organik melalui proses fotosintesis adalah ...
a. Archaebacteria
b. eubacteria
c. cyanobacteria
d. klorophyta
e. protozoa
37. Tempat hidup dari archaebacteria adalah ...
a. kawah gunung berapi, laut mati dan usus besar hewan
herbivora
b. tanah gambut, kawah gunung merapi, dan usus besar
hewan karnovora
c. kawah gunung berapi, laut mati dan usus besar hewan
karnivora
d. tanah gambut, laut mati, dan usus besar hewan
herbivora
e. tanah gambut, laut mati dan usus besar hewan karnivora
38. Kelompok organisme yang dikenal dengan nama bakteri
sejati adalah ...
a. Archaebacteria
b. eubacteria
c. cyanobacteria
d. klorophyta
e. protozoa
39. Struktur sel yang tidak dimiliki oleh organisme
prokariot adalah ...
a. dinding sel
b. membran sel
c. membran plasma
d. membran inti
e. selaput semipermeabel
40. Nama bakteri yang memiliki banyak flagel pada salah
satu ujung tubuhnya adalah ...
a. peritriks
b. amfitriks
c. Lopotriks
d. monotriks
e. ditriks
41. Bakteri yang menyebabkan penyakit thypus adalah
bakteri yang mempunyai flagela bertipe
a. peritriks
b. amfitriks
c. Lopotriks
d. monotriks
e. ditriks
42. Beberapa fungsi organel prokariot
1. membentuk jembatan konjugasi
2. tempat sintesis protein
3. alat untuk mengapung
4. alat gerak
5. alat tukar-menukar materi genetik
Fungsi dari filli adalah ...
a. 1 - 2 - 3
b. 3 - 4 - 5
c. 1 - 3 - 5
d. 2 - 4 - 4
e. 2 - 3 - 5
43. Bakteri yang menyebabkan penyakit Radang paru paru
atau Pnemonia adalah koloni bakteri yang membentuk.
a. streptococcus
b. diplococcus
c. sarcina
d. staphylococcus
e. tetracoccus
44. Racun eksotoksi adalah ...
a. racun yang dihasilkan oleh bakteri gram negatif
b. racun yang dihasilkan oleh bakteri gram positif
c. racun yang dihasilkan oleh bakteri yang sudah mati
d. racun yang dihasilkan oleh archaebacteria
e. racun yang dihasilkan oleh cyanobacteria
45. Berdasarkan letak flagelnya, Bentuk bakteri
Escherisia coli adalah ...
a. peritriks
b. lopotriks
c. amfitriks
d. monotriks
e. ditriks
46. Dinding sel archaebacteria berbeda dengan eubacteria,
yaitu dinding sel archaebacteria ...
a. terbuat dari selulosa
b. memiliki peptidoglikan yang tebal
c. memiliki peptidoglikan yang tipis
d. memiliki bentuk berlapis-lapis
e. mengandung ribosom
47. Berdasarkan cara respirasinya, Archaebacteria
termasuk dalam kelompok ...
a. aerob
b. aerob obligat
c. anaerob
d. anaerob obligat
e. anaerob fakultatif
48. Tempat hidup dari bakteri metanogen adalah ...
a. kawah gunung berapi
b. laut mati
c. tanah gambut
d. usus besar hewan herbivora
e. tempat lembab
49. nama jenis archaebacteria yang dapat hidup di
lingkungan yang sangat asin adalah ...
a. halofit
b. termofil
c. metanogen
d. acidofil
e. termoacidofil
50. bakteri gram negatif adalah ...
a. bakteri yang memiliki lapisan peptidoglikan tipis dan
dengan pewarnaan gram menghasilkan warna ungu
b. bakteri yang memiliki lapisan peptidoglikan tipis dan
dengan pewarnaan gram menghasilkan warna biru
c. bakteri yang memiliki lapisan peptidoglikan tebal dan
dengan pewarnaann gram menghasilkan warna biru
d. bakteri yang memiliki lapisan peptidoglikan tebal dan
dengan pewarnaan gram menghasilkan warna ungu
e. bakteri yang tidak memiliki lapisan peptidoglikan pada
dinding selnya, tapi hidup di daerah yang ekstrim
51. dapatkah bakteri gram positif diberantas dengan
menggunakan antibiotika?
a. tidak bisa karena lapisan peptidoglikannya tipis
b. tidak bisa karena peptidoglikannya tebal
c. bisa, karena lapisan peptidoglikannya tipis
d. bisa, karena lapisan peptidoglikannya tebal
e. bisa karena lapisan peptidoglikan berubah-ubah
ketebalannya
52. kelompok Cyanobacterium atau alga biru yang berbentuk
benang adalah ...
a. Nostoc
b. rivularia
c. anabaena
d. gleocapsa
e. oscilatoria
53. Cyanobacteria merupakan prokariot yang dapat
melakukan fotosintesis. jenis pigmen yang dimiliki utama yang dimiliki
organisme ini adalah ...
a. pigmen hijau-biru
b. pigmen hijau kuning
c. pigmen biru kuning
d. pigmen biru merah
e. pigmen biru jingga
54. Pada cyanobacteria terdapat struktur yang memiliki
kemampuan untuk memfiksasi nitrogen yaitu ...
a. heterokist
b. hormogonium
c. sporokiste
d. spiroseta
e. nematokist
55. Escherisia coli termasuk kelompok bakteri enterik
sebab ...
a. hidup di dalam tubuh makhluk hidup
b. merupakan bakteri anaerob fakultatif
c. menghasilkan racun atau toksik
d. mampu mengubah bahan organik menjadi anorganik
e. mengubah selolusa menjadi metanaDETAIL
Ciri-Ciri Bakteri
Dalam klasifikasi terbaru,
bakteri dibagi menjadi 2 bagian kelompok besar yaitu Archeobacteria dan Eubacteria diantara
keduanya memiliki ciri khusus, dan secara umum bakteri mempunyai ciri-ciri
sebagai berikut:
1. Tubuh Uniseluler (bersel
satu)
2. Prokariotik atau tidak
memiliki membran inti sel.
3. Berdiameter antara 0,5 – 1 mikron dengan
panjang 1 – 20 mikron, sehingga hanya dapat dilihat menggunakan mikroskop.
4. Hidup secara soliter atau berkoloni.
5. Mempunyai dinding sel.
6. Kosmopolit yaitu habitatnya meliputi
daerah yang luas dan di berbagai ekosistem.
7. Umumnya tidak berklorofil meskipun
beberapa jenis bakteri memiliki pigmen seperti klorofil sehingga
mampu berfotosintesis dan bersifat autotrof.
B. Struktur Bakteri
Struktur bakteri dibagi
menjadi 2 yaitu :
1. Struktur Dasar Bakteri
Struktur dasar bakteri adalah
struktur yang dimiliki oleh hampir semua jenis bakteri diantaranya :
a. Bahan Inti, merupakan pusat
pengendali aktivitas sel yang berisi DNA, bakteri memiliki rantai tunggal DNA
yang disebut nukleoid.
b. Sitoplasma, yaitu cairan sel
dimana didalamnya terdapat asam nulkeat, protein, karbohidrat, lemak dan lain
lain.
c. Ribosom, adalah butiran-butiran
organel yang tersebar dalam sitoplasma yang mengandung molekul RNA sebagai
tempat sintesis protein.
d. Granula penyimpanan, adalah
tempat menyimpan cadangan makanan yang dibutuhkan.
e. Membran plasma (selaput sitoplasma),
bersifat selektif permeabel (hanya dapat dilalui molekul atau zat tertentu).
Tersusun atas protein dan fosfolipid, membran plasma memiliki fungsi antara
lain sebagai alat transpor elekron dan proton, pengatur pengangkutan senyawa
dan tempat terbentuknya mesosom.
f. Dinding Sel, berfungsi
sebagai pelindung dan pemberi bentuk tubuh sel bakteri, tersusun atas
peptidoglikan yaitu gabungan protein dan polisakarida. Peptidoglikan membagi
bakteri menjadi bakteri gram positif (peptidoglikan tebal) contohnya neisseria
gonorrhea, treponema pallidum. dan bakteri gram negatif (peptidoglikan tipis)
contohnya, escherichia coli, staphylococcus aureus.
2. Struktur tambahan bakteri
Struktur tambahan bakteri
biasanya hanya dimiliki oleh jenis bakteri tertentu atau bisa dikatakan tidak
dimiliki oleh jenis bakteri tertentu, struktur tambahan bakteri terdiri atas :
a. Flagela (flagellum), yaitu alat
gerak bakteri yang biasanya terdapat pada bakteri yang hidup di habitat air,
beberapa tipe bakteri berdasarkan letak flagelanya yaitu:
1) Atrik, yaitu bakteri yang
tidak berflagela
2) Monotrik, bakteri yang memiliki
satu flagela.
3) Amfitrik, dua buah flagela
di kedua ujung tubuhnya.
4) Lofotrik, terdapat segerombol
flagela di salah satu ujung tubuh.
5) Peritrik, flagelanya
terdapat di seluruh permukaan tubuh.
b. Kapsul atau lapisan lendir, bila
lapisannya tebal disebut kapsul dan bila lapisan tipis disebut lapisan lendir,
kapsul tersusun atas polisakarida dan air, memiliki fungsi antara lain:
1) Alat melekat
bakteri pada sel inang
2) Mencegah
kekeringan pada sel bakteri
3) Alat
perlindungan dan sumber makanan bagi bakteri.
c. Pilus dan fimbria, yaitu
struktur berbentuk rambut halus yang menonjol dari dinding sel, mirip flagelum
tetapi lebih pendek dan terdapat pada bakteri negatif sedangkan fimbria adalah
struktur sejenis pilus tetapi lebih pendek.
d. Klorosom, yaitu struktur yang
berada di bawah membran plasma, klorosom mengandung pigmen klorofil dan pigmen
lainnya yang berperan dalam proses fotosintesis, klorosom hanya terdapat pada
bakteri yang mampu melakukan fotosintesis.
e. Vakuola gas, berguna agar bakteri
dapat mengapung di permukaan air untuk memperoleh cahaya, vakuola gas hanya
terdapat pada bakteri di air yang mampu melakukan fotosintesis.
f. Endospora, merupakan bentuk
bakteri ketika sedang istirahat, endospora ditemui di beberapa jenis bakteri
gram positif dan terbentuk di dalam sel bakteri jika kondisi lingkungan tidak
menguntungkan bagi kehidupan bakteri. Endospora tersusun atas sitoplasma, DNA,
dan ribosom. Dinding endospora yang tebal tahan terhadap kondisi ekstrim
seperti kekeringan, radiasi cahaya, suhu, maupun zat kimia. Jika kondisi
lingkungan memungkinkan maka endospora akan tumbuh menjadi sel bakteri baru.
C. Bentuk Bakteri
Adanya dinding sel pada
bakteri menyebabkan bakteri mempunyai bentuk yang bersifat tetap. Bentuk
bakteri terdiri dari :
1. Coccus (kokus/bola)
a. Monococcus, yaitu bentuk
kokus/bola tunggal, contoh: Neisseria gonorrhoeae
b. Diplococcus, yaitu bentuk bola
berpasangan, contoh : Diplococcus pneumoniae.
c. Tetracoccus, yaitu empat sel
bakteri berdempetan membentuk segi empat.
d. Streptococcus, bentuk bola
berantai, contoh: Azotobacter, Bacillus anthracis.
e. Staphylococcus, berbentuk bola
bergerombol seperti buah anggur, contoh: Staphylococcus aureus.
f. Sarcina, bentuk bola berdempetan
membentuk kubus, contoh : Sarcina sp.
2. Bacillus (basil/batang)
a. Monobacillus, bentuk batang
tunggal, contoh Escherichia coli, Lactobacillus.
b. Diplobacillus, bentuk batang
berpasangan
c. Streptobacillus, bentuk
batang berkoloni berbentuk rantai, contoh : Azotobacter, streptobacillus
moniliformis.
3. Spirillum (spiral)
a. Spirillum, bentuk spiral
bergelombang, contoh spirillum minor.
b. Spirochaeta, yaitu bentuk sel
seperti sekrup atau kumparan, contoh : treponema pallidum.
4. Vibrio (koma), yaitu bentuk sel bakteri
seperti tanda baca koma atau kurang dari setengah lingkaran.
D. Klasifikasi Bakteri
Bakteri merupakan organisme
yang dapat kita temui hidup di segala habitat dan dengan jumlah yang sangat
banyak dibandingkan dengan makhluk hidup lain. Bakteri secara umum dapat dibagi
menjadi dua kelompok besar yaitu Archaebacteria dan Eubacteria, selain itu
bakteri juga dapat diklasifikasikan berdasarkan sumber nutrisi dan kebutuhan
oksigennya.
1. Klasifikasi bakteri secara umum, bakteri
terbagi menjadi :
a. Archaebacteria
Berasal dari bahasa yunani : archaio yang
berarti kuno.Archaebacteria adalah kelompok bakteri primitif,
archaebacteria dianggap sebagai nenek moyang dari bakteri yang ada sekarang
archaebacteria bersifat prokariotik, dapat hidup di habitat yang ekstrim
seperti daerah berkadar garam tinggi maupun di tempat bersuhu panas, memiliki
ciri khusus seperti :
- Dinding selnya tidak mengandung
peptidoglikan
- Membran selnya mengandung lipida
berikatan eter.
- Ribosomnya mengandung beberapa jenis RNA
polimerase
Archaebacteria terbagi menjadi
beberapa kelompok, yaitu :
1) Bakteri Metanogen/metanogenik
Bakteri jenis ini mendapatkan
makanan dari sisa-sisa pembusukan bahan organik, dimana proses pembusukan
tersebut menghasilkan gas metana (CH4).
Bakteri metanogen yang
bersifat anaerobik dan kemosintetik ini hidup di habitat rawa dan lingkungan
yang berkadar oksigen rendah, bakteri yang hidup di laut mendapatkan makanan
dari bahan organik yang jatuh ke laut.
2) Bakteri Halofil/halofilik
Berasal dari kata halo :
garam, dan philos : suka, bakteri halofil yaitu bakteri yang dapat hidup di
lingkungan yang berkadar garam tinggi , bakteri ini mampu melakukan
fotosintesis dengan menggunakan klorofil bacteriorhadopsin (ungu), contoh :
Halobacterium sp.
3) Bakteri Termoasidofil/termoasidofilik
Bakteri ini hidup di
lingkungan ekstrim yang memiliki suhu tinggi serta tingkat keasaman tinggi,
contohnya seperti kawah gunung vulkanik dari gunung berapi dan mata air
bersulfur.
b. Eubacteria
Eubacteria memiliki ciri
khusus yang membedakannya dari archaebacteria diantaranya :
- Adanya peptidoglikan pada
dinding selnya
- Membran plasmanya mengandung lipida
berikatan ester
- Ribosom mengandung satu jenis RNA
polimerase
Eubacteria dibagi menjadi 5 kelompok yaitu :
1) Bakteri Gram Positif
Beberapa bakteri gram positif
dapat berfotosintesis dan ada yang bersifat kemoheterotrof, bakteri ini dapat
membentuk endospora ketika keadaan lingkungan kurang menguntungkan. Contoh :
Bacillus, Clostridium, Mycobacterium tubercolosis dan Mycoplasma gallisepticum.
2) Cyanobacteria
Cyanobacteria dahulu dikenal
dengan ganggang hijau biru, hidup soliter maupun berkoloni. Cyanobacteria ada
yang bersel satu dan juga bersel banyak, tidak mempunyai membran inti dan tidak
memiliki banyak organela serta tidak memiliki alat gerak. Cyanobacteria
berukuran antara 1 - 60 µm.
Pada cyanobacteria terdapat
pigmen klorofil, karoten, dan pigmen tambahan berupa fikosianin (biru), dan
fikoeritrin (merah). Contoh cyanobacteria adalah Anabaena, Oscillatoria
rubescens, nostoc, anabaena azollae, azolla pinnata.
3) Proteobacteria
Proteobacteria bersifat
autotrof dan terdapat klorofil pada membran sel, protebacteria dapat dibedakan
menjadi tiga kelompok yaitu :
a) Bakteri ungu kemoautotrof
b) Proteobacteria kemoautotrof
c) Proteobacteria kemoheterotrof
Bakteri ungu terdapat pada
endapan danau, kolam, dan lumpur, contoh Chromatium. Proteobacteria
kemoautotrof hidup bebas atau bersimbiosis dengan makhluk hidup lain. Sedangkan
proteobacteria kemoheterotrof hidup di saluran pencernaan contoh Escherichia
coli, salmonella.
4) Spirochetes
Spirochetes sebagian hidup
bebas dan sebagian hidup sebagai parasit dan menjadi penyebab penyakit,
spirochetes merupakan bakteri gram negatif yang bersifat kemoheterotrof dan
berukuran antara 5 – 250 µm dan berbentuk spiral. Pada spirochetes terdapat
filamen aksial berupa serabut disepanjang tubuhnya dan berfungsi untuk gerakan
berputar. Contoh: Treponema pallidum, leptospira interrogans.
5) Chlamydias
Chlamydias merupakan kelompok
bakteri dengan ukuran paling kecil yaitu antara 0,2 – 1,5 µm dengan bentuk
tidak beraturan. Chlamydias hanya dapat hidup sebagai parasit dalam sel-sel
makhluk hidup lain. Contoh: chlamydias trachomatis.
2. Klasifikasi bakteri menurut kebutuhan
oksigennya, yaitu :
a. Bakteri Aerob, yaitu bakteri yang
memerlukan oksigen untuk memperoleh energi, contoh Nitrosomonas, nitrosococcus.
b. Bakteri Anaerob, yaitu bakteri
yang tidak membutuhkan oksigen untuk memperoleh energi, energi diperoleh antara
lain dengan cara fermentasi. Contoh Esherichia coli, lactobacillus.
3. Klasifikasi bakteri menurut sumber
nutrisinya, yaitu :
a. Bakteri Autotrof, yaitu
bakteri yang dapat mengubah bahan anorganik menjadi bahan
organik sebagai sumber makanan, bakteri autotrof dibagi menjadi dua kelompok
yaitu:
1) Bakteri fotoautotrof (fototrof) adalah
jenis bakteri yang menggunakan cahaya matahari sebagai sumber energinya.
2) Bakteri kemoautotrof, adalah
bakteri yang memperoleh energi dengan cara mengoksidasi senyawa-senyawa kimia
anorganik. Contohnya Nitrosomonas, nitrobacter.
b. Bakteri Heterotrof, adalah
bakteri yang memproleh energi dari bahan-bahan organik, dibagi menjadi :
1) Bakteri heterotrof yang
hidup sebagai parasit, yaitu jenis bakteri yang mendapatkan makanan dari
organisme lain yang menjadi inangnya, contoh Mycobacterium tubercolosis.
2) Bakteri heterotrof yang
hidup sebagai saprofit, yaitu bakteri yang mendapatkan makanan dengan cara
merombak bahan organik menjadi bahan anorganik melalui proses fermentasi,
bakteri ini biasanya apatogen. Contoh : Escherichia coli, clostridium
sporageus.
E. Reproduksi Bakteri
1. Reproduksi Aseksual
Pada umumnya bakteri melakukan
reproduksi atau berkembang biak secara aseksual dengan cara pembelahan biner
yang biasanya setiap sel bakteri membelah menjadi dua. Proses pembelahan biner
dimulai dari replikasi DNA, pemisahan sitoplasma kemudian diikuti dengan
terbentuknya dinding pemisah, dan selanjutnya terbentuklah dua sel bakteri.
2. Reproduksi Seksual
Reproduksi bakteri secara
seksual yaitu dengan pertukaran materi genetik dari satu bakteri ke bakteri
lain, disebut juga rekombinasi genetik atau paraseksual. Rekombinasi bakteri
menghasilkan dua sel bakteri yang terjadi dengan tiga cara yaitu :
a. Transformasi : yaitu proses
pemindahan sedikit materi genetik (DNA) ke dalam sel bakteri lain.
b. Transduksi : pemindahan
materi genetik dari satu sel bakteri ke bakteri lain dengan perantaraan virus
(bakteriofage)
c. Konyugasi : perpindahan
materi genetik yang berupa plasmid langsung melalui kontak sel dengan membentuk
struktur seperti jembatan dengan sel bakteri didekatnya.
F. Contoh Peranan Bakteri.
Dalam kehidupan manusia
bakteri mempunyai peranan yang menguntungkan maupun merugikan.
1. Contoh peranan bakteri yang
menguntungkan
a. Bidang Pertanian :
1) Bakteri nitrit (nitrosomonas dan
nitrococcus) dan bakteri nitrat (nitrobacter) adalah bakteri yang membantu
proses pembentukan senyawa nitrat dalam tanah
2) Azetobacter, clostrodium pasteurianum,
rodospirillium rubrum dan rhizobium mampu mengikat N2 bebas dari udara.
b. Bidang Industri :
1) Lactobacillus casei, berperan dalam
fermentasi keju dan yoghurt.
2) Acetobacter xylinum, menghasilkan asam
cuka dan natan de coco
3) Streptococcus lactis, berperan dalam
fermentasi keju dan mentega.
4) Propionibacterium berperan dalam
pembuatan asam propionat.
5) Methanomonas methanica berperan dalam
pembuatan gas bio.
6) Clostridium acebutylicum menghasilkan
aseton dan butanol.
c. Bidang Farmasi :
1) Streptococcus griseus, menghasilkan
antibiotik streptomisin
2) Streptomyces venezuelae, menghasilkan
antibiotik kloromisetin
3) Streptomyces aureofaciens, menghasilkan
antibiotik aureomisin
4) Streptomyces rimosus, menghasilkan
antibiotik tetrasiklin
5) Pseudomonas denitrificans, menghasilkan
vitamin B12
6) Bacillus brevis, menghasilkan antibiotik
tirotrisin.
7) Bacillus subtilis, menghasilkan
antibiotik basitrasin.
8) Bacillus polymyxa, menghasilkan
polymixin.
d. Bidang lain :
1) Escherichia coli, pembusukan sisa
makanan di usus serta membantu pembentukan vitamin K.
2. Contoh berbagai bakteri yang merugikan.
Beberapa bakteri menyebabkan
penyakit pada manusia, hewan dan tumbuhan.
a. Penyebab penyakit pada manusia, antara
lain :
1) Mycobacterium tubercolosis, penyebab
penyakit TBC
2) Mycobacterium leprae, penyebab penyakit
lepra.
3) Clostrodium tetani, penyebab penyakit
tetanus.
4) Salmonella typhi, dapat menyebabkan
penyakit tifus.
5) Vibrio cholerae, penyebab penyakit kolera.
6) Shigella disentriae, penyebab penyakit
disentri.
7) Pasteurella pestis, penyebab panyakit
pes.
8) Diplococcus pneumonia, menyebabkan
radang paru-paru.
9) Treponema pallidium,menyebabkan penyakit
sifilis.
10) Neisseria gonorrheaea, menyebabkan
penyakit gonoro.
11) Leptospira sp., dapat menyebabkan
penyakit leptospirosis.
b. Penyebab penyakit pada hewan dan
tumbuhan, antara lain :
1) Bacillus anthracis, menyebabkan penyakit
antraks pada sapi, kerbau, dan domba.
2) Brucella abortus, menyebabkan penyakit
bruselosis pada sapi.
3) Pseudomonas solanacearum, penyebab
penyakit pada tomat, terung, dan tembakau.
4) Agrobacterium tumafaciens, penyebab
penyakit tumor pada tumbuhan.
5) Xanthomonas citri, penyebab penyakit kanker
pada batang jeruk.
6) Erwinia tracheiphila, menyebabkan busuk
pada daun labu.
7) Psedomonas cattleyae, menyebabkan busuk
pada daun anggrek.
c. Menyebabkan rusaknya makanan, yaitu :
1) Clostridium botulinum, menyebabkan
makanan kaleng rusak.
2) Pseudomonas cocovenenans, menyebabkan
rusaknya tempe.
3) Leuconostoc mesentroides, menyebabkan
makanan basi.
G. Faktor-faktor yang mempengaruhi
pertumbuhan bakteri.
Faktor-faktor yang
mempengaruhi pertumbuhan bakteri atau kondisi pertumbuhan optimum dari bakteri
yaitu :
1. Suhu/temperatur, pada umumnya
bakteri dapat tumbuh baik pada suhu antara 250C sampai 350C.
2. Derajat keasaman atau pH
3. Konsentrasi garam
4. Sumber nutrisi, dimana
tersedia sumber nutrisi untuk pertumbuhan bakteri
5. Kelembapan, dimana bakteri
umumnya hidup di lingkungan yang memiliki kelembapan tinggi karena sangat
menguntungkan untuk pertumbuhan bakteri.
6. Cahaya, umumnya cahaya dapat
merusak sel bakteri karena ionisasi pada komponen sel yang menghambat
pertumbuhan bakteri.
7. Zat kimia, antibiotik, logam berat dan
senyawa-senyawa kimia tertentu dapat menghambat bahkan mematikan bakteri.
Adapun faktor-faktor diatas
bervariasi menurut spesies bakterinya
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