27.1 Structural and functional adaptations contribute to prokaryotic success Flashcards
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 undergo ready fossilization in sedimentary rock.
E) They possess typical prokaryotic flagella.
B) They are subject to lysis in hypotonic conditions.
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.
B) Their cell walls are composed of very different biochemicals.
3) 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
A) plasma membrane
4) Which statement about bacterial cell walls is false?
A) Bacterial cell walls differ in molecular composition from plant cell walls.
B) Cell walls prevent cells from bursting in hypotonic environments.
C) Cell walls prevent cells from dying in hypertonic conditions.
D) Bacterial cell walls are similar in function to the cell walls of many protists, fungi, and
plants.
E) Cell walls provide the cell with a degree of physical protection from the environment.
C) Cell walls prevent cells from dying in hypertonic conditions.
5) Which of these is the most common compound in the cell walls of gram-positive bacteria?
A) cellulose
B) lipopolysaccharide
C) lignin
D) peptidoglycan
E) protein
D) peptidoglycan
6) Penicillin is an antibiotic that inhibits enzymes from catalyzing the synthesis of
peptidoglycan, so which prokaryotes should be most vulnerable to inhibition by penicillin?
A) mycoplasmas
B) gram-positive bacteria
C) archaea
D) gram-negative bacteria
E) endospore-bearing bacteria
B) gram-positive bacteria
7) 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 which can inhibit phagocytosis, what is the correct sequence of structures
penetrated by B. bacteriophorus on its way to the preyʹs cytoplasm?
1. membrane composed mostly of lipopolysaccharide
2. membrane composed mostly of phospholipids
3. peptidoglycan
4. capsule
A) 2 → 4 → 3 →1
B) 1 → 3 → 4 → 2
C) 1 → 4 → 3 → 2
D) 4 → 1 → 3 → 2
E) 4 → 3 → 1 → 2
D) 4 → 1 → 3 → 2
8) 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.
A) undergo death by plasmolysis.
9) 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 transformed bacterium.
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 bacteriumʹs progeny.
E) the temporary possession by this bacterium of a completely diploid genome.
B) the rapid spread of tetracycline resistance to other bacteria in that habitat.
10) 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. flagellum
3. endospore
4. fimbriae
5. plasmids
A) 1 only
B) 1 and 4
C) 1 and 5
D) 1, 3, and 5
E) 2, 4, and 5
D) 1, 3, and 5
11) Which two structures play direct roles in permitting bacteria to adhere to each other, or to
other surfaces?
1. capsules
2. endospores
3. fimbriae
4. plasmids
5. flagella
A) 1 and 2
B) 1 and 3
C) 2 and 3
D) 3 and 4
E) 3 and 5
B) 1 and 3
12) 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 ʺmotorʺ embedded in the cell wall and plasma membrane.
D) a basal body that is similar in structure to the cellʹs centrioles.
C) a complex ʺmotorʺ embedded in the cell wall and plasma membrane.
13) Prokaryotic ribosomes differ from those present in eukaryotic cytosol. Because of this,
which of the following is correct?
A) Some selective antibiotics can block protein synthesis of bacteria without effects on protein synthesis 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
A) Some selective antibiotics can block protein synthesis of bacteria without effects on protein synthesis in the eukaryotic host.
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 multiple chromosomes, ʺpackedʺ with a relatively large amount of protein.
D) The prokaryotic chromosome is not contained within a nucleus but, rather, is found at the nucleoid region.
E) Prokaryotic genomes are composed of linear DNA (that is, DNA existing in the form of a line with two ends).
D) The prokaryotic chromosome is not contained within a nucleus but, rather, is found at the nucleoid region.
15) 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
A) lack antibiotic-resistant genes.
B) lack a cell wall.
C) lack a chromosome.
D) lose base pairs from its chromosome.
E) be unable to survive in its normal environment.
A) lack antibiotic-resistant genes.
