MB Chapter 27

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 provide the cell with a degree of physical protection from the environment.
d. Bacterial cell walls are similar in function to the cell walls of many protists, fungi, and plants.
e. Cell walls prevent cells from dying in hypertonic conditions.

e. Cell walls prevent cells from dying in hypertonic conditions.

Which of these is the most common compound in the cell walls of gram-positive bacteria?

a. cellulose
b. protein
c. lipopolysaccharide
d. lignin
e. peptidoglycan

e. peptidoglycan

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 swim through these thick and viscous materials
c. are obligate anaerobes
d. undergo death by lysis
e. are unable to metabolize the glucose or fructose, and thus starve to death

a. undergo death by plasmolysis

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, 3, and 5
d. 1 and 5
e. 2, 4, and 5

c. 1, 3, and 5

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 a chromosome
b. lack antibiotic-resistant genes
c. lack a cell wall
d. be unable to survive in its normal environment
e. lose base pairs from its chromosome

b. lack antibiotic-resistant genes

Regarding prokaryotic reproduction, which statement is correct?

a. Prokaryotes form gametes by meiosis
b. Prokaryotes skip sexual life cycles because their life cycle is too short
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 feature the union of haploid gametes, as do eukaryotes

d. Mutation is a primary source of variation in prokaryote populations

Which of these statements about prokaryotes is correct?

a. Genetic variation in bacteria is not known to occur, nor should it occur, because of their asexual mode of reproduction
b. Bacterial cells conjugate to mutually exchange genetic material
c. Their genetic material is confined within a nuclear envelope
d. They divide by binary fission, without mitosis or meiosis
e. The persistence of bacteria throughout evolutionary time is due to their genetic homogeneity (i.e., sameness)

d. They divide by binary fission, without mitosis or meiosis

Gram-positive bacteria:
-appear purple after Gram staining
-have a thick peptidoglycan
-alcohol rinse does not remove crystal violet

Gram-negative bacteria:
-appear pink after Gram staining
-alcohol rinse easily removes crystal violet
-have a thin peptidoglycan layer
-have an outer membrane as part of their cell well structure

Both Gram negative and positive bacteria:
-have a plasma membrane

Autotrophs
can synthesize organic molecules from inorganic sources

Heterotrophs
cannot synthesize organic molecules from inorganic sources and must obtain organic material by consuming other organisms

Chemoautotrophs
need only carbon dioxide as a carbon source and obtain energy by oxidizing inorganic substances

Photoautotrophs
use light energy to drive the synthesis of organic compounds from carbon dioxide

Photoheterotrophs
use light to generate ATP but must obtain carbon in organic form

Chemoheterotrophs
must consume organic molecules for both engery and carbon

Phototrophs
general term for organisms that obtain energy from light

Chemotrophs
general term for organisms that obtain energy from chemicals

Autotrophs may be chemotrophs or phototrophs
True

Heterotrophs may be chemotrophs or phototrophs
True

All chemotrophs are autotrophs
False

All autotrophs are chemotrophs
False

Chemotrophs may be autotrophs or heterotrophs
True

All phototrophs are heterotrophs
False

All heterotrophs are phototrophs
False

Phototrophs may be autotrophs or heterotrophs
True

Obligate aerobes
require oxygen for cellular respiration and cannot live without it

Obligate anaerobes
poisoned by oxygen and obtain energy through anaerobic respiration or fermentation

Facultative anaerobes
use oxygen for cellular respiration if it is present, but they may obtain energy through anaerobic respiration or fermentation when oxygen is not available

Which group is not one of the three major divisions of life-forms determined by Woese?

a. Archaea
b. Prokarya
c. Eukarya
d. Bacteria

b. Prokarya

What characteristics were used to classify organisms before Woese’s tree of life analysis?

a. Presence of membrane-bound nucleus
b. Composition of the cell wall
c. Differences in ribosomal RNA sequences
d. Number of cells in the organisms

a. Presence of a membrane-bound nucleus

True or false?
Data showing that the Bacteria were the first lineage to diverge from the common ancestor of all living organisms suggest that the Archaea and Eukarya are more closely related to each other than they are to the Bacteria
True

Which of the following statements about phylogenetic trees is true?

a. A paraphyletic group consists of an ancestral population and all of its descendants
b. A paraphyletic group has not experienced lateral gene transfer
c. A monophyletic group consists of a common ancestor and some of its descendants
d. A paraphyletic group consists of a common ancestor and some of its descendants

d. A paraphyletic group consists of a common ancestor and some of its descendants

Which molecule did Carl Woese study to produce his tree of life?

a. DNA
b. Messanger RNA
c. Ribosomal RNA
d. Ribosome

c. Ribosomal RNA

What is lateral gene transfer?

a. Inheritance of gene through meiosis
b. Inheritance of gene through mitosis
c. Physical transfer of a gene from a species in one lineage to a species in another lineage
d. Inheritance of a gene from a parent

c. Physical transfer of a gene from a species in one lineage to a species in another linage

Which of the following is an important source of endotoxin in gram-negative species?

a. endospore
b. capsule
c. sex pilus
d. cell wall
e. flagellum

d. cell wall

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, 3, and 4
b. 2 and 3
c. 1 only
d. 1 and 2
e. all four terms

a. 1, 3, and 4

In a hypothetical situation, a bacterium lives on the surface of a leaf, where it obtains nutrition from the leaf’s nonliving, waxy covering, while inhibiting the growth of other microbes that are plant pathogens. If this bacterium gains access to the inside of a leaf, it causes a fatal disease in the plant. Once the plant dies, the bacterium and its offspring decompose the plant. What is the correct sequence of ecological roles played by the bacterium in the situation described here? Use only those that apply.
1. nutrient recycler
2. mutualist
3. commensal
4. parasite
5. primary producer

a. 1, 2, 3
b. 2, 4, 1
c. 1, 3, 4
d. 2, 3, 4
e. 1, 2, 5

b. 2, 4, 1

Foods can be preserved in many ways by slowing or preventing bacterial growth. Which of these methods would not generally bacterial growth?

a. Irradiation: Kills bacteria by mutating their DNA to such an extent that their DNA-repair enzymes are overwhelmed
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. Refrigeration: Slows bacterial metabolism and growth
e. Canning in heavy sugar syrup: Creates osmotic conditions that remove water from most bacterial cells

b. Closing previously opened containers: Prevents more bacteria from entering, and excludes O2

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 synthesize peptidoglycan
b. deficient in certain vitamins
c. unable to fix carbon dioxide
d. unable to fix nitrogen
e. antibiotic resistant

b. deficient in certain vitamins

Many physicians administer antibiotics to patients at the first sign of any disease symptoms. Why can this practice cause more problems for these patients, and for others not yet infected?

a. The antibiotic administered may kill viruses that had been keeping the bacteria in check
b. Overuse of antibiotics can select for antibiotic-resistant strains of bacteria
c. Antibiotics ay interfere with the ability to identify the bacteria present
d. Particular patients may be allergic to the antibiotic
e. Antibiotics may cause other side effects in patients

b. Overuse of antibiotics can select for antibiotic-resistant strains of bacteria