Bacteria and Viruses

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bacteria and Viruses

 

 

Multiple Choice
Identify the choice that best completes the statement or answers the question.
 1.
Many microscopic organisms or entities have been identified as pathogens, including all of the following except:
a.
protozoa.
b.
viruses.
c.
fungi.
d.
bacteria.
e.
None of the above, all may be pathogenic.
 2.
Which of the following statements about bacteria is false?
a.
A small percentage of bacteria are pathogenic.
b.
Some bacteria can photosynthesize.
c.
Bacteria are important decomposers.
d.
Bacteria are not cellular and are sometimes not classified as life forms.
e.
Bacteria convert atmospheric nitrogen into ammonia and then nitrates that can be used by plants.
 3.
Viruses were first identified:
a.
because they caused an infection and formed colonies on nutrient agar plates.
b.
because they were seen in the light microscope.
c.
because they caused an infection and were small enough to pass through filters that trapped bacteria.
d.
because they were smaller than bacteria and had all the properties of living organisms.
e.
because they caused an infection and were seen in the electron microscope.
 4.
The protein coat of a virus is called the:
a.
capsule.
b.
capsid.
c.
exospore.
d.
phage.
e.
pilus.
 5.
Viruses that attack bacteria are called:
a.
phages.
b.
bacteriods
c.
prions.
d.
virons.
e.
viroids.
Figure 23-01
Use the figure below to answer the corresponding questions.
nar001-1.jpg

 6.
The structure of the virus in Figure 23-01 that is common to all viruses is:
a.
2.
b.
3.
c.
4.
d.
5.
e.
All of the above.
 7.
In Figure 23-01, the function of the structure labeled 3 is:
a.
attachment to a host cell.
b.
locomotion.
c.
mate recognition.
d.
replication.
e.
to take over host cell mechanisms.
 8.
Viruses are classified by:
a.
the sequence of their DNA.
b.
structural similarities.
c.
the sequence of their rRNA genes.
d.
the traditional Linnaean binomial nomenclature system.
e.
an international committee.
 9.
Viruses:
a.
are very tiny cells on the order of 500 nm.
b.
contain both RNA and DNA.
c.
cannot independently perform metabolic activities.
d.
have a standard morphology that includes a capsid, tail, and tail fibers.
e.
All of the above.
 10.
Viruses:
a.
are usually species-specific.
b.
may have multiple origins.
c.
are probably related to mobile genetic elements.
d.
may have escaped from cells.
e.
All of the above.
 11.
Phages are being considered for:
a.
vectors in gene therapy experiments.
b.
antibiotics in bacterial infections.
c.
gene transfer vectors in animal cells.
d.
being equivalent to the first living organisms.
e.
All of the above.
 12.
Temperate viruses:
a.
always destroy their host immediately.
b.
are considered virulent.
c.
do not always destroy their host.
d.
do not undergo a lysogenic cycle.
e.
undergo a lytic cycle.
 13.
Virulent (lytic) phages:
a.
infect viruses.
b.
destroy bacteria.
c.
infect, but do not destroy bacteria.
d.
infect virions.
e.
infect prions.
 14.
The five stages of a lytic infection are attachment, penetration, _____________, assembly, and release.
a.
lysis
b.
prophage
c.
lysogenesis
d.
transduction
e.
replication
 15.
A prophage:
a.
is phage DNA that is integrated into viral DNA.
b.
is phage DNA that is integrated into bacterial DNA.
c.
replicates only when the eukaryotic cell it infects replicates.
d.
is an underdeveloped lytic virus.
e.
is a bacterial cell about to lyse.
 16.
The bacterium that causes botulism disease is harmless until it:
a.
is infected by lytic bacteria.
b.
is infected by certain retroviruses.
c.
contains a certain prophage DNA.
d.
is irradiated by UV radiation.
e.
is infected by prions.
 17.
____________ conversion occurs when a bacterium carrying viral genes takes on new, atypical characteristics.
a.
Transducing
b.
Lysogenic
c.
Prophage
d.
Lytic
e.
Reverse
 18.
The specificity of viruses to different types of cells is due to _____________ sites on the host cell.
a.
prophage
b.
receptor
c.
transduction
d.
penetration
e.
transcription
 19.
Retroviruses differ from other RNA viruses by:
a.
having reverse transcriptase instead of RNA-dependent RNA polymerase.
b.
the shape of their capsid.
c.
the way they infect their host cells.
d.
the sugar coating on their capsids.
e.
lytically destroying their hosts.
 20.
Which of the following diseases is not caused by a virus?
a.
rabies
b.
polio
c.
warts in humans
d.
chickenpox
e.
Lyme disease
 21.
Which of the following identifies a group of DNA viruses?
a.
retroviruses
b.
herpesviruses
c.
paramyxoviruses
d.
filovirus
e.
picornaviruses
 22.
Viral proteins can damage host cells by:
a.
increasing the rate of fermentation within the host.
b.
producing endotoxins.
c.
causing a decline in coordination and increased irritability.
d.
preventing transcription of viral nucleic acids.
e.
overwhelming the host cell with a large number of viruses.
 23.
Viral infections in humans spread via the circulatory system. Viral infections in plants spread from cell to cell via:
a.
endocytosis.
b.
plasmodesmata.
c.
infected seeds.
d.
pili.
e.
transformation.
 24.
Human viruses can enter human cells by fusion with the cell membrane or by:
a.
diffusion into the cell.
b.
passage through specific protein channels.
c.
coating themselves with lipids that cloak their entrance into the cell.
d.
endocytosis.
e.
hitchhiking onto protein signals entering the cell.
 25.
Viroids cause a variety of plant diseases and are composed only of:
a.
strands of RNA.
b.
strands of DNA.
c.
protein coats.
d.
peptidoglycan.
e.
a capsid.
 26.
Mad cow disease is an example of an infection caused by a:
a.
bacterium.
b.
bacteriophage.
c.
retrovirus.
d.
viroid.
e.
prion.
 27.
_____________ is credited with the discovery of prions as a new biological principle of infection.
a.
Stanley Prusiner
b.
Anton van Leeuwenhoek
c.
Dmitrii Ivanowsky
d.
Stanley Brenner
e.
Carl Woese
 28.
A symptom of a transmissible spongiform encephalopathy (TSE) is:
a.
degeneration of the digestive tract.
b.
progressive immune deficiency.
c.
degeneration of the brain and central nervous system.
d.
inflammation of the reproductive organs.
e.
influenza-like symptoms.
 29.
The volume of a typical bacterium is about ____________ the volume of a typical eukaryotic cell.
a.
equal to
b.
a half
c.
a tenth
d.
a hundredth
e.
a thousandth
 30.
A chain of round bacteria would be called:
a.
spirilla.
b.
diplococci.
c.
bacilli.
d.
streptococci.
e.
streptobacilli.
 31.
Rod-shaped bacteria are called:
a.
streptococci.
b.
bacilli.
c.
diplococci.
d.
vibrio.
e.
spirochete.
Figure 23-02
Use the figure below to answer the corresponding questions.
nar002-1.jpg

 32.
The structure in Figure 23-02 labeled C is:
a.
a ribosome.
b.
the plasma membrane.
c.
the capsule.
d.
the cell wall.
e.
the flagellum.
 33.
What is the function of the structure labeled A in Figure 23-02?
a.
to adhere to surfaces or other bacteria
b.
to prevent phagocytosis
c.
support and protection in hypotonic conditions
d.
transmission of DNA between bacteria
e.
locomotion
 34.
Even though bacteria lack membrane-bound organelles, such as chloroplasts and mitochondria, they can still perform the functions of these organelles by localizing certain metabolic enzymes on:
a.
the nuclear membranes.
b.
the endoplasmic reticulum.
c.
the plasma membrane.
d.
ribosomes.
e.
the cell wall.
 35.
Most bacterial cells keep from bursting in a hypotonic environment by:
a.
an efficient water pump.
b.
a tough cell membrane.
c.
pumping large quantities of salts into the cell.
d.
a rigid cell wall.
e.
a stiff capsule.
 36.
Gram-positive bacteria would stain __________ in a gram stain because of a thick layer of __________ in their cell walls.
a.
green; peptidoglycan
b.
purple; peptidoglycan
c.
green; cellulose
d.
purple; polysaccharides
e.
red; polysaccharides
 37.
The walls of Eubacteria contain peptidoglycan, which is:
a.
lipids crosslinked with sugars.
b.
sugars crosslinked with proteins.
c.
a protein.
d.
a lipid.
e.
a polysaccharide.
 38.
Penicillin works most effectively against gram-positive bacteria because:
a.
penicillin affects cell membranes.
b.
they have a thick peptidoglycan cell wall and penicillin affects the synthesis of peptidoglycans.
c.
they have special protein channels that allow penicillin to enter the cell and halt the cell cycle.
d.
they are smaller than gram-negative bacteria and, thus, easily take up penicillin by diffusion.
e.
they contain prophages that negatively interact with penicillin.
 39.
Some bacteria avoid a host’s immune system by means of:
a.
efficient use of their flagella.
b.
ameboid motion.
c.
their capsule.
d.
changing their cell wall structure.
e.
eliminating the use of a membrane.
 40.
Bacteria:
a.
are incapable of locomotion.
b.
move by means of pili
c.
move by means of cilia.
d.
move by means of a rotating flagella.
e.
move by means of a whiplike flagella.
 41.
Small circles of DNA called ______________ exist in addition to the bacterial chromosome.
a.
capsids
b.
plasmids
c.
chromatids
d.
pili
e.
centromeres
 42.
Small hairlike structures on the surface of bacteria are called:
a.
capsids.
b.
pili.
c.
chromatids.
d.
plasmids.
e.
virons.
 43.
Plasmids of bacteria often have genes involved in:
a.
reproduction.
b.
motility.
c.
viral resistance.
d.
antibiotic resistance.
e.
photosynthesis.
 44.
Pili are involved in adhesion of bacterial cells to a substrate or host, or in transmission of __________ between bacteria.
a.
ribosomes
b.
cytoplasm
c.
vectors
d.
RNA
e.
DNA
 45.
Prokaryotes have their genetic information stored in:
a.
several small, circular pieces of DNA.
b.
a single, small, circular piece of DNA.
c.
a large, linear piece of DNA.
d.
several small, linear pieces of DNA.
e.
a large, circular piece of DNA.
 46.
_______________ is a form of genetic exchange in bacteria that involves contact between two cells.
a.
Transformation
b.
Transduction
c.
Conjugation
d.
Binary fission
e.
Budding
 47.
_____________ are dormant structures formed by bacteria in response to adverse environmental conditions.
a.
Capsids
b.
Endospores
c.
Exotoxins
d.
Endotoxins
e.
Heterocysts
 48.
Most bacteria are:
a.
photoheterotrophs.
b.
chemoheterotrophs.
c.
autotrophs.
d.
heterotrophs.
e.
chemoautotrophs.
 49.
A bacterium that gains nourishment from dead organisms is referred to as:
a.
an autotroph.
b.
a parasite.
c.
a saprotroph.
d.
a chemoautotroph.
e.
a pathogen.
 50.
A(an) ___________________ bacterium would not be able to survive in the presence of oxygen.
a.
facultative aerobic
b.
facultative anaerobic
c.
facultative autotrophic
d.
obligate aerobic
e.
obligate anaerobic
 51.
The most common mode of reproduction in bacteria is:
a.
binary fission.
b.
transformation.
c.
transduction.
d.
conjugation.
e.
mitosis.
 52.
The first indication that Archae were different from the Eubacteria came from differences noted in their:
a.
cell wall.
b.
preferred habitats.
c.
16 S rRNA sequence.
d.
protein synthesis machinery.
e.
resistance to antibiotics.
 53.
The Archaea differ from the Eubacteria and eukaryotes by having different ____________ in their cell membranes, but they are similar to eukaryotes in their ____________ process.
a.
sugars; replication
b.
sugars; transcription
c.
lipids; replication
d.
lipids; transcription
e.
proteins; transcription
Figure 23-03
Use the figure below to answer the corresponding questions.
nar003-1.jpg

 54.
Which of the following groups from Figure 23-03 represents gram-negative bacteria?
a.
Spirochetes
b.
Protists
c.
Methanogens
d.
Halophiles
e.
None of the above.
 55.
Which of the following groups from Figure 23-03 is a member of the Eubacteria domain?
a.
Fungi
b.
Halophiles
c.
Chlamydias
d.
Protists
e.
More than one of the above.
 56.
About how many different species of bacteria have been classified?
a.
200
b.
2,000
c.
4,000
d.
20,000
e.
40,000
 57.
The most significant difference between the Archaea and the Eubacteria is:
a.
lack of a nuclear envelope in the Archaea.
b.
the absence of the 70S ribosomes in the Eubacteria.
c.
the presence of a single filament flagellum in the Eubacteria.
d.
the absence of peptidoglycans in the cell walls of the Archaea.
e.
All of the above.
 58.
One difference between the Archaea and the Eukarya is:
a.
the lack of a nuclear envelope in the Archaea.
b.
the absence of the 70S ribosomes in the Archaea.
c.
the presence of membrane-bound organelles in the Archaea.
d.
the presence of peptidoglycans in the cell walls of the Archaea.
e.
the presence of simple RNA polymerase in the Archaea.
 59.
One unique characteristic associated with some of the extreme halophilic Archaea is:
a.
that they are found at deep-sea vents on the sea floor.
b.
that they are a source of most known antibiotics.
c.
that they have photosynthetic ability involving a purple bacteriorhodopsin pigment.
d.
that they fix atmospheric nitrogen that is then used by plants.
e.
that most form symbiotic associations.
 60.
_____________ Archae are typically found in abnormally hot environments.
a.
Extreme halophile
b.
Extreme thermophile
c.
Pyrrhanogen
d.
Metanogen
e.
Any of the above.
 61.
Most prokaryotes belong to the:
a.
Fungi.
b.
Archaea.
c.
Protista.
d.
Eubacteria.
e.
Viroids.
 62.
Bacterial ____________ cause systemic symptoms such as fever, whereas bacterial ____________ cause more specific maladies.
a.
phages; prophages
b.
prophages; phages
c.
endotoxins; exotoxins
d.
exotoxins; endotoxins
e.
exotoxins; phages
 63.
The bacterial reproductive parasite Wolbachia is known to:
a.
eradicate males from a population.
b.
convert males into females.
c.
cause infected females to lay eggs that develop without fertilization.
d.
reduce the number of males in a population.
e.
All the above.
 64.
The symbiotic bacteria found in the root nodules of legumes:
a.
supply the plant with the nitrogen it needs in the form of nitrates.
b.
are motile, soil-dwelling bacteria.
c.
belong to the genus Rhizobium.
d.
are gram-negative Eubacteria.
e.
All of the above.
 65.
Koch’s postulates include all the following except:
a.
when a sample of a pure culture is injected into a healthy host causes the same disease.
b.
a sample of the microorganism from a diseased host can be grown in pure culture.
c.
the microorganism can be recovered from an experimentally infected host.
d.
the microorganism must be visible in the electron microscope.
e.
the pathogen must be present in every individual with the disease.
 66.
The first bacteria that was clearly identified as the cause of an infectious disease was:
a.
Legionella pneumophila, which causes Legionnaires’ disease.
b.
Chamydia sp., which causes pelvic inflammatory disease in women.
c.
Clostridium botulinum, which causes botulism.
d.
Vibrio cholerae, which causes cholera.
e.
Bacillus anthracis, which causes anthrax.
 

Short Answer
 67.
Compare and contrast a virus and a bacterium.

 68.
List the characteristics of the following groups and identify examples for each: Archaea, Eubacteria, and Eukarya.

 69.

Compare and contrast the metabolic diversity of bacteria in one of the two groups below.

A. Obligate anaerobes, facultative anaerobes, and aerobes
B. Autotrophic and heterotrophic bacteria

 70.
Identify and briefly discuss two ecological roles filled by bacteria.

 

Essay
 71.
Describe the theory that attempts to explain the species specificity of viruses to their hosts.

 72.
Discuss the distinction between gram-negative and gram-positive bacteria. In the laboratory, how is this determined? What are differences between these two groups of bacteria?

 73.
Describe endotoxins and exotoxins. What effects do they each have on infected persons?

 

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