AP Biology Chapter 27

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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

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

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

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

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

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

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

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

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

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

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

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

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
can eukaryotes.

A

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

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

16

Which of the following is composed almost entirely of peptidoglycan?

A) endospore

B) sex pilus

C) flagellum

D) cell wall

E) capsule

D

17

Which of the following requires ATP to function, and permits some species to respond to
taxes (plural of taxis)?
A) endospore
B) sex pilus
C) flagellum
D) cell wall
E) capsule

C

18

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

E

19

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) sex pilus
C) flagellum
D) cell wall
E) capsule

A

20

Which of the following is a structure that permits conjugation to occur?
A) endospore
B) sex pilus
C) flagellum
D) cell wall
E) capsule

B

21

Which of the following is an important source of endotoxin in gram-negative species?
A) endospore
B) sex pilus
C) flagellum
D) cell wall
E) capsule

D

22

) If this structure connects the cytoplasm of two bacteria, one of these cells may gain new
genetic material:
A) endospore
B) sex pilus
C) flagellum
D) cell wall
E) capsule

B

23

Which of the following contains a copy of the chromosome, along with a small amount of
dehydrated cytoplasm, within a tough wall?
A) endospore
B) sex pilus
C) flagellum
D) cell wall
E) capsule

A

24

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.

D

25

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.

C

26
card image

) Which term best describes what has occurred among the experimental populations of cells
over this 8-year period?
A) microevolution
B) speciation
C) adaptive radiation
D) sexual selection
E) stabilizing selection

A

27
card image

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) 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

D

28
card image

) 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

C

29
card image

) If the vertical axis of Figure 27.1 refers to ʺDarwinian fitness,ʺ 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

E

30

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

B

31

E. coli cells typically make most of their ATP by metabolizing glucose. Under the conditions
of this experiment, what should be true of E. coliʹs 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.

C

32

If the experimental population of E. coli lacks an F factor or F plasmid, and if bacteriophage
are excluded from the bacterial cultures, then which of these is a 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) both A and C above

D

33
card image

Among the six statements below, which two best account for the results obtained by the
researchers (see Figure 27.1)?
1. Low-glucose conditions caused mutations that made individual E. coli cells better suited
to these conditions.
2. Daughter cells acquired the ability to tolerate low-glucose conditions as they received
the enzymes and membrane components that had been modified by their mother cell.
3. The initial E. coli population may have included some cells whose genes favored their
survival in low-glucose conditions–OR–such genetic variants arose by chance early in the
experiment.
4. The first few generations of E. coli in low-glucose conditions responded to the challenge
by increasing the use of certain enzymes and ion pumps, while decreasing the use of others.
This behavior was recorded in their gene sequences, which were later transmitted to
daughter cells.
5. From generation to generation, there was an increase in the proportion of the
experimental populations adapted to low-glucose conditions, because such bacteria
produced relatively more offspring than did ancestral bacteria under low-glucose
conditions.
6. During each generation, individual cells evolved to increase their survival in
low-glucose conditions.

A

34

Which term is least closely associated with the others?
A) Hfr cells making use of a sex pilus
B) rolling circle replication
C) the ʺtoilet paperʺ model of replication
D) conjugation involving an F factor
E) recombination involving a bacteriophage

E

35
card image

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 recipientʹs chromosome
E) reversal of the direction of conjugation

D

36
card image

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) It has a greater number of introns.

C

37
card image

) 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
5. ʺtoilet paperʺ replication of recipient cellʹs plasmids
A) 1 and 4
B) 2 and 3
C) 3 and 5
D) 1 and 3
E) 4 and 5

B

38
card image

During which two times can the recipient accurately be described as ʺrecombinantʺ 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

A

39
card image

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 recipientʹs chromosome, what prevents this
from occurring?
B) Why do geneticists refer to the same structure by at least three different names: sex
pilus, mating bridge, and conjugation tube? Why all the jargon?
C) What forces are generally responsible for disrupting the mating bridge?
D) How is it that a recipient cell does not necessarily become an Hfr cell as the result of
conjugation with an Hfr cell?
E) What makes a cell an ʺHfr cellʺ?

A

40
card image

Among the six statements below, which two best account for the results obtained by the
researchers (see Figure 27.1)?

3. The initial E. coli population may have included some cells whose genes favored their
survival in low-glucose conditions–OR–such genetic variants arose by chance early in the
experiment.

5. From generation to generation, there was an increase in the proportion of the
experimental populations adapted to low-glucose conditions, because such bacteria
produced relatively more offspring than did ancestral bacteria under low-glucose
conditions.
During each generation, individual cells evolved to increase their survival in
low-glucose conditions.
A) 3 and 5
B) 1 and 5
C) 2 and 4
D) 1 and 6
E) 1 and 3

A

41

) 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.

A

42

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.

D

43

Which of the following features of prokaryotic biology involves metabolic cooperation
among cells?
A) binary fission
B) endospore formation
C) endotoxin release
D) biofilms
E) photoautotrophy

D

44

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

B

45

Plant-like photosynthesis that releases O2 occurs in
A) cyanobacteria.
B) chlamydias.
C) archaea.
D) actinomycetes.
E) chemoautotrophic bacteria

A