Question 1

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 consists partly of an outer membrane of lipopolysaccharide?
A) only one species
B) two species
C) three species
D) four species

Accepted Answer

Three of the species (B, C, and E) have a cell wall consisting partly of an outer membrane of lipopolysaccharide, as indicated by the presence of both an outer membrane and lipopolysaccharide in their characteristics. The other two species (A and D) lack either an outer membrane or lipopolysaccharide in their characteristics, so they do not fit this description.

Question 2

The following question refers to the 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.

The cells in the 12 cell lines grown in low-glucose conditions showed the effects of which of the following processes?
A) gene flow and genetic drift
B) natural selection and mutation
C) natural selection and gene flow
D) conjugation and transformation

Accepted Answer

The cells in the 12 cell lines were subjected to natural selection and mutation due to the low glucose conditions they were grown in. The fitness of the individuals was tested, indicating that natural selection was taking place. The other options (A, C, D) involve genetic exchange, which was not mentioned in the experiment.

Question 3

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?

Accepted Answer

Chloramphenicol can inhibit prokaryotic ribosomes but not eukaryotic ribosomes because they are structurally different. However, mitochondria in eukaryotic cells have their own ribosomes that are similar in structure to prokaryotic ribosomes. Therefore, chloramphenicol can potentially inhibit mitochondrial ribosomes as well.

Question 4

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 capable of directed movement?
A) species A
B) species B
C) species C
D) species D

Accepted Answer

The answer of The following table depicts characteristics of five...

Question 5

Use the information in the following paragraph to answer the question.
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 ________.
A) gram-negative cell wall
B) peptidoglycan in the cell wall
C) lipopolysaccharides in the cytoplasm
D) long polypeptides in the cell wall

Accepted Answer

The fact that the bacterium is not susceptible to the penicillin family of antibiotics suggests that it has a gram-negative cell wall, as these types of bacteria have an outer membrane that makes them more resistant to certain antibiotics. Peptidoglycan, lipopolysaccharides, and long polypeptides are all components found in the cell wall of bacteria, but none of these directly make them resistant to penicillin.

Question 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?
A) nucleoid, fimbriae, and plasmids
B) endospore, fimbriae, and plasmids
C) fimbriae, nucleoid, and endospore
D) plasmids, nucleoid, and endospore

Accepted Answer

Plasmids allow for the exchange of genetic information that can confer antibiotic resistance, while the nucleoid houses the bacterium's DNA. The endospore is a highly resistant structure that allows the bacterium to persist through adverse conditions. Fimbriae are appendages used for attachment to surfaces and do not play a significant role in antibiotic resistance or resistance to adverse conditions.

Question 7

Jams, jellies, preserves, honey, and other foods with high sugar content hardly ever become contaminated by bacteria, even when the food containers are left open at room temperature. This is because bacteria that encounter such an environment ________.
A) undergo death as a result of water loss from the cell
B) are unable to metabolize the glucose or fructose, and thus starve to death
C) are obligate anaerobes
D) are unable to swim through these thick and viscous materials

Accepted Answer

High sugar content creates a hypertonic environment, causing water to leave bacterial cells, leading to dehydration and death.

Question 8

Use the information in the following paragraph to answer the question.
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 should one be able to locate a complete chromosome of this bacterium?
A) mitochondrion
B) nucleoid
C) nucleus
D) plasmid

Accepted Answer

The paragraph mentions that the bacterium contains no plasmids, indicating that it does have a chromosome, which is located in the nucleoid region. The other options, mitochondrion and nucleus, are not applicable as they are found in eukaryotic cells rather than prokaryotic cells like bacteria.

Question 9

The following question refers to the 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.

Imagine that after generation 20,000, the experimental cells were grown in high-glucose conditions for 20,000 generations (using the same transfer process described). Refer to the y-axis on the graph and predict the fitness of the new lines when tested in low- and high-glucose conditions.
A) low: 1.0; high: 1.0
B) low: 1.6; high: 1.6
C) low: 1.0; high: 1.6
D) low: 1.6; high: 1.0

Accepted Answer

The answer of The following question refers to the figure.
In...

Question 10

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 lack ________.
A) antibiotic-resistant genes
B) a cell wall
C) a chromosome
D) water in its cytoplasm

Accepted Answer

Plasmids are extra-chromosomal pieces of DNA that can contain genes for antibiotic resistance, among other things. If the endospore did not contain any plasmids with antibiotic-resistant genes, then the regenerated bacterium will not have them either.

Question 11

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?
A) phospholipid membrane, capsule, peptidoglycan, lipopolysaccharide membrane
B) lipopolysaccharide membrane, peptidoglycan, capsule, phospholipid membrane
C) lipopolysaccharide membrane, capsule, peptidoglycan, phospholipid membrane
D) capsule, lipopolysaccharide membrane, peptidoglycan, phospholipid membrane

Accepted Answer

Bdellovibrio bacteriophorus first penetrates the capsule, then the outer lipopolysaccharide membrane, followed by the peptidoglycan layer, and finally the inner phospholipid membrane to reach the cytoplasm of a gram-negative bacterium.

Question 12

Use the following information and graph to answer the question.
The figure below 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).

What process is occurring at Time C that is decreasing the DNA content?
A) crossing over
B) cytokinesis
C) degradation of DNA that was not retained in the recipient's chromosome
D) reversal of the direction of conjugation

Accepted Answer

At Time C, the DNA content is decreasing due to degradation of DNA that was not retained in the recipient's chromosome. This means that some of the DNA fragments from the Hfr cell did not get exchanged with the recipient's chromosome and therefore are being degraded.

Question 13

Use the following information and graph to answer the question.
The figure below 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).

Which two processes are responsible for the shape of the curve at Time B?
A) transduction and rolling circle replication of single-stranded Hfr DNA
B) entry of single-stranded Hfr DNA and rolling circle replication of single-stranded Hfr DNA
C) rolling circle replication of single-stranded Hfr DNA and activation of DNA pumps in the plasma membrane
D) transduction and activation of DNA pumps in the plasma membrane

Accepted Answer

The graph shows an increase in the amount of DNA present in the recipient cell, indicating that DNA from the Hfr cell is entering the recipient cell. This process involves the entry of single-stranded Hfr DNA. The shape of the curve at Time B is due to rolling circle replication of the single-stranded Hfr DNA within the recipient cell, which leads to a rapid increase in the amount of DNA present. Therefore, the correct answer is B, entry of single-stranded Hfr DNA and rolling circle replication of single-stranded Hfr DNA. The other options do not accurately describe the processes occurring during Hfr cell conjugation. Transduction is a different mechanism of DNA transfer that does not involve conjugation. Activation of DNA pumps in the plasma membrane is not a known process in Hfr cell conjugation.

Question 14

Use the following information and graph to answer the question.
The figure below 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).

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.

Accepted Answer

The answer of Use the following information and graph to...

Question 15

Which of the following observations about flagella is accurate and is consistent with the scientific conclusion that the flagella from eukaryotes and bacteria evolved independently?
A) The flagella of both eukaryotes and bacteria are made of the same protein, but the configuration is different.
B) The mechanics of movement and protein structure are the same in these flagella, but there are significant genetic differences.
C) Although the mechanism of movement in both flagella is the same, the protein that accomplishes the movement is different.
D) The protein structure and the mechanism of movement in eukaryotes flagella are different from those of bacteria flagella.

Accepted Answer

The observation that the protein structure and the mechanism of movement in eukaryotes flagella are different from those of bacteria flagella is the most accurate and consistent with the scientific conclusion that the flagella from eukaryotes and bacteria evolved independently. This indicates that the flagella in these two domains of life have different evolutionary origins and mechanisms of development. Option A is incorrect because if the flagella were made of the same protein with different configuration, it could suggest a common evolutionary origin. Option B is incorrect because significant genetic differences can occur even in evolutionary homologs. Option C is incorrect because it contradicts the observation that the mechanism of movement in both flagella is the same.

Question 16

Which of the following observations about flagella is accurate and is consistent with the scientific conclusion that the flagella from archaea and bacteria evolved independently?
A) The flagella of the two groups differ in size.
B) The protein structures in the flagella are different.
C) The mechanisms of rotation are similar.
D) Both groups have flagella like those found in eukaryotes.

Accepted Answer

The statement that "the protein structures in the flagella are different" is accurate and supports the scientific conclusion that the flagella from archaea and bacteria evolved independently. This is because different protein structures suggest that they were not inherited from a common ancestor but rather evolved separately. The other answer choices are not consistent with the independent evolution of flagella in archaea and bacteria.

Question 17

Use the information in the following paragraph to answer the question.
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.
Which of the following statements about the cell wall is most probable?
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.

Accepted Answer

The mention of lipopolysaccharide (LPS) in the outer membrane of the cell wall suggests that it is a Gram-negative bacterium. Gram-negative bacteria have a thin layer of peptidoglycan in their cell wall, surrounded by an outer membrane of LPS. This is the only option that accurately describes the composition of the cell wall. Option A is incorrect, as a phospholipid bilayer is a characteristic of the cell membrane, not the cell wall. Option B is incorrect, as Gram-negative bacteria should turn pink after Gram staining. Option D is incorrect, as this type of cell wall is typical of Gram-positive bacteria.

Question 18

Termites eat wood, but many do not produce enzymes themselves that will digest the cellulose in the wood. Instead, some termites house a complex community of protozoa, bacteria, and archaea that could help digest the cellulose. Imagine an experiment that fed termites either wood only or wood and antibiotics, and then measured the amount of energy extracted from the wood. If both groups gained equal amounts of energy, which of the conclusions is the most logical?
A) We would conclude that the protozoa contributed to digestion of cellulose and lignin.
B) We would conclude that the archaea contributed to digestion of cellulose and lignin.
C) We would conclude that the bacteria did not contribute to digestion of cellulose and lignin.
D) We would conclude that none of the three groups were needed to digest cellulose and lignin.

Accepted Answer

The answer of Termites eat wood, but many do not...

Question 19

Use the information in the following paragraph to answer the question.
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

Accepted Answer

Fimbriae are hair-like structures that protrude from the surface of bacterial cells and allow them to adhere to surfaces. In this case, the bacterium adheres to the intestinal lining using a feature that protects it from various threats. The other choices (B, C, and D) do not play a role in adherence to the intestinal lining in this scenario.

Question 20

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

Accepted Answer

The answer of The following table depicts characteristics of five...

Quiz 27: Bacteria and Archaea

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 consists partly of an outer membrane of lipopolysaccharide?

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?

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 capable of directed movement?

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?

Jams, jellies, preserves, honey, and other foods 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 ________.

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 lack ________.

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?

Which of the following observations about flagella is accurate and is consistent with the scientific conclusion that the flagella from eukaryotes and bacteria evolved independently?

Which of the following observations about flagella is accurate and is consistent with the scientific conclusion that the flagella from archaea and bacteria evolved independently?

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?