Exam 2 Flashcards

An agent used to reduce the number of bacteria on a toilet would most accurately be called a(n)

• antiseptic
• disinfectant
• aseptic
• fungicide
• virucide

Which of the following pairs of terms is mismatched?

• germicide – kills microbes
• bacteriostatic – kills vegetative bacterial cells
• sterilant – destroys all living microorganisms
• virucide – inactivates viruses
• fungicide – kills yeasts and molds

The fate of E. coli O157:H7 in apple cider held at 8°C for 2 weeks, with and without preservatives, is shown below:

A suspension of 10⁶ Bacillus cereus endospores was put in a hot-air oven at 170°C. Plate counts were used to determine the number of endospores surviving at the time intervals shown.

In the figure, what is the thermal death time?

• 60 minutes
• 150°C
• 100°C
• 120 minutes
• The answer cannot be determined based on the information provided.

In the table, which compound was the most effective against Staphylococcus?

• A
• B
• C
• D
• The answer cannot be determined based on the information provided.

Which of the following does NOT achieve sterilization?

• pasteurization
• supercritical fluids
• autoclave
• ethylene oxide
• dry heat

Which of the following chemical agents is used for sterilization?

• soap
• chlorine
• ethylene oxide
• phenolics
• alcohol

Which graph in the figure best depicts the effect of placing the culture in an autoclave for 15 minutes at time x?

• a
• b
• c
• d
• e

A suspension of 10⁶ Bacillus cereus endospores was put in a hot-air oven at 170°C. Plate counts were used to determine the number of endospores surviving at the time intervals shown.

In the figure, the decimal reduction time (D value) for the culture, which is defined as the time to reduce a population by one log, is approximately

• 10 minutes
• 40 minutes
• 0 minutes
• 30 minutes
• 60 minutes.

Microorganisms placed in high concentrations of salts and sugars undergo lysis.

• True
• False

The following data were obtained by incubating gram-positive bacteria in nutrient medium + disinfectant for 24 hours, then transferring one loopful to nutrient medium (subculturing). (+ = growth; - = no growth)

In the table, which disinfectant was bactericidal?

• Doom
• K.O.
• Mortum
• Sterl
• The answer cannot be determined based on the information provided.

Which of the following results in lethal damage to nucleic acids?

• heat and radiation
• heat
• radiation
• certain chemicals
• heat, radiation, and some chemicals

Application of heat to living cells can result in all of the following EXCEPT

• alteration of membrane permeability
• breaking of hydrogen bonds
• decreased thermal death time
• damage to nucleic acids
• denaturation of enzymes.

Autoclaving is the most effective method of moist heat sterilization.

• True
• False

All of the following are methods of food preservation EXCEPT

• high pressure
• desiccation
• ionizing radiation
• osmotic pressure
• microwaves.

Bacteriophage replication differs from animal virus replication because only bacteriophage replication involves

• assembly of viral components.
• adsorption to specific receptors.
• replication of viral nucleic acid.
• lysis of the host cell.
• injection of naked nucleic acid into the host cell.

• Which of the following substances is used for surgical hand scrubs?
• glutaraldehyde
• chlorine bleach
• soap
• chlorhexidine
• phenol

Desiccation is a reliable form of sterilization

• True
• False

Which of the following methods is used to preserve food by slowing the metabolic processes of foodborne microbes?

• nonionizing radiation
• ionizing radiation
• freezing
• lyophilization
• pasteurization

Which of the following is a limitation of the autoclave?

• It cannot inactivate viruses
• It requires an excessively long time to achieve sterilization
• It cannot be used with glassware
• It cannot be used with heat-labile materials
• It cannot kill endospores.

The preservation of beef jerky from microbial growth relies on which method of microbial control?

• ionizing radiation
• desiccation
• supercritical CO₂
• filtration
• lyophilization

In the table, which compound was the most effective against E. coli?

• A
• B
• C
• D
• The answer cannot be determined based on the information provided.

Which of the following best describes the pattern of microbial death?

• The pattern varies depending on the antimicrobial agent
• The pattern varies depending on the species
• The cells in a population die at a constant rate
• All the cells in a culture die at once
• Not all of the cells in a culture are killed.

Which graph in the figure best depicts the effect of placing the culture at 7°C at time x?

• a
• b
• c
• d
• e

Which of the following disinfectants acts by disrupting the plasma membrane

• soaps
• bisphenols
• aldehydes
• heavy metals
• halogens

In the table, which disinfectant is the most effective at stopping bacterial growth?

• Doom
• K.O.
• Mortum
• Sterl
• The answer cannot be determined based on the information provided.

Some antimicrobial chemicals are considered to be disinfectants and antiseptics.

• True
• False

Which of the following regarding antimicrobial control agents is FALSE?

• Contaminating organic debris such as blood or sputum will decrease effectiveness.
• Some agents affect microbial cell membranes by dissolving lipids.
• Most chemical agents can achieve sterility.
• Some agents are utilized as both an antiseptic and a disinfectant.
• Some agents kill by denaturing microbial cell proteins.

In the table, which compound was bactericidal?

• A
• B
• C
• D
• The answer cannot be determined based on the information provided.

A bacterial species differs from a species of eukaryotic organisms in that a bacterial species

• has a limited geographical distribution.
• does not breed with other species.
• can be distinguished from other bacterial species.
• is a population of cells with similar characteristics.
• breeds with its own species.

Which statement regarding viral species is true?

• Viral species are classified within the Kingdom Plantae in the Domain Eukarya.
• Viral species are taxonomically differentiated based upon their cell wall.
• Viruses are classified as prokaryotes.
• Viral species are not classified as part of any of the three domains.

Use the dichotomous key in the table to identify a gram-negative cell that ferments lactose and uses citric acid as its sole carbon source.

• Lactobacillus
• Citrobacter
• Staphylococcus
• Escherichia
• Pseudomonas

Into which group would you place a unicellular organism that has 70S ribosomes and a peptidoglycan cell wall?

• Protist
• Plantae
• Animalia
• Bacteria
• Fungi

At this point in time, scientists believe the vast majority of the domain Bacteria have been discovered.

• True
• False

Into which group would you place a photosynthetic organism that lacks a nucleus and has a thin peptidoglycan wall surrounded by an outer membrane?

• Proteobacteria (gram-negative bacteria)
• Fungi
• Animalia
• Firmicutes (gram-positive bacteria)
• Plantae

The highest level in the current taxonomic hierarchy is "Kingdom."

• True
• False

Which of the following is the original basis for differentiation of the three domains of life?

• Ribosomal RNA sequences
• Nutritional patterns
• The presence or absence of ribosomes
• Optimum growth temperature

In the cladogram shown in the figure, which two organisms are most closely related?

• Streptomyces and Micrococcus
• Streptomyces and Mycobacterium
• Mycobacterium and Lactobacillus
• Micrococcus and Mycobacterium
• Streptomyces and Lactobacillus

Which of the following statements about archaea is FALSE?

• Some are thermoacidophiles; others are extreme halophiles.
• They lack peptidoglycan in their cell walls.
• Some produce methane from carbon dioxide and hydrogen.
• They are prokaryotes.
• They evolved before bacteria

Which one of the following statements is a reason for NOT classifying viruses in one of the threedomains of life (Bacteria, Archaea, Eukarya) rather than in a fourth separate domain?

• Viruses are obligate parasites.
• Viruses are not composed of cells.
• Viruses direct anabolic pathways of host cells.
• Some viruses can incorporate their genome into a host's genome.

Which of the following characterizes the Domain Bacteria?

• complex cellular structures
• prokaryotic cells; ether linkages in phospholipids
• eukaryotic cells; ester linkages in phospholipids
• multicellular
• prokaryotic cells; ester linkages in phospholipids

Which of the following is the best evidence for a three-domain system?

• There are three distinctly different types of nuclei.
• Some bacteria live in extreme environments.
• There are three distinctly different Gram reactions.
• There are three distinctly different sets of metabolic reactions.
• Nucleotide sequences in ribosomal RNA vary between all three domains.

In the scientific name Enterobacter aerogenes, Enterobacter is the

• specific epithet.
• kingdom.
• genus.
• family.
• order.

Into which group would you place a photosynthetic cell that lacks a nucleus?

• Bacteria
• Plantae
• Fungi
• Protista
• Animalia

In the figure, the closest ancestor for both species "a." and species "b." would be which of the following?

• 1
• 2
• 3
• 4
• 5

The phylogenetic classification of bacteria is based on

• Gram reaction.
• cell morphology.
• diseases.
• habitat.
• rRNA sequences.

In the table, which features are found in nearly all eukarya?

• 2, 3, 5
• 3, 5
• 2, 3
• 1, 2, 5
• 1, 4, 6

Use the dichotomous key in the table to identify a gram-negative coccus.

• Pseudomonas
• Neisseria
• Streptococcus
• Staphylococcus
• Micrococcus

Which of the following groups in the Domain Archaea require high salt concentrations for survival?

• Archaezoa
• hyperthermophiles
• methanogens
• halophiles

If two organisms have similar rRNA sequences, you can conclude that they

• live in the same place.
• evolved from a common ancestor
• will both ferment lactose.
• will have different G-C ratios.
• mated with each other.

Which of the following statements about members of the Kingdom Plantae is FALSE?

• They synthesize organic molecules.
• They are multicellular.
• They are composed of eukaryotic cells.
• They undergo photosynthesis.
• They use organic carbon sources.

In the table, which feature(s) is (are) found only in prokaryotes?

• 4, 6
• 2
• 1
• 1, 2, 3
• 2, 4, 5

The arrangement of organisms into taxa

• is based on evolution.
• was designed by Charles Darwin.
• shows relationships to common ancestors.
• shows degrees of relatedness between organisms.
• is arbitrary

You discovered a unicellular organism that lacks a nucleus and peptidoglycan. You suspect the organism is in the group

• Fungi.
• Archaea.
• Animalia.
• Bacteria.
• Plantae.

Into which group would you place a multicellular organism that has a mouth and lives inside the human liver?

• Plantae
• Proteobacteria (gram-negative bacteria)
• Firmicutes (gram-positive bacteria)
• Animalia
• Fungi

A clone is

• a mound of cells on an agar medium.
• genetically identical cells derived from a single cell.
• a genetically engineered cell.
• a taxon composed of species.

A genus can best be defined as

• a taxon composed of one or more species and a classification level lying below family
• a taxon composed of families.
• a taxon comprised of classes.
• the most specific taxon.
• a taxon belonging to a species.

Chloroplasts possess circular DNA and reproduce by binary fission.

• True
• False

________ are a diverse group of eukaryotic organisms that are similar in rRNA sequences, but quite different from each other in motility types and ecology. They have been used previously as a "catch-all" for organisms that couldn't be easily classified into other groups.

• Methanogens
• Fungi
• Plants
• Protists

Which type of organism would NOT be included in the Domain Eukarya?

• bacterium
• ameba
• fungus
• protist

Bacteria and Archaea are similar in which of the following?

• peptidoglycan cell walls
• considered prokaryotic cells
• sensitivity to antibiotics
• methionine as the start signal for protein synthesis
• plasma membrane ester linkage

What is the outstanding characteristic of the Kingdom Fungi?

• All members are photosynthetic.
• Members absorb dissolved inorganic matter.
• Members absorb dissolved organic matter.
• All members are microscopic.
• All members are macroscopic.

Into which group would you place a multicellular heterotroph with chitin cell walls?

• Plantae
• Archaea
• Bacteria
• Fungi
• Animalia

In the figure, species "c." is most closely related to which of the following?

• a
• b
• c
• d
• e

Which of the following statements about the members of the Kingdom Animalia is FALSE?

• They are multicellular.
• They are heterotrophs.
• They ingest nutrients through a mouth.
• They are composed of eukaryotic cells.
• They undergo photosynthesis.

Which of the following do you expect to be MOST resistant to high temperatures?

• Escherichia coli
• Bacillus subtilis
• Neisseria gonorrhoeae
• Streptococcus pyogenes
• Staphylococcus aureus

Borrelia is classified as a spirochete because it

• possesses an axial filament.
• is aerobic.
• is a rod.i
• s transmitted by ticks.
• is a pathogen.

Which of the following can survive in phagocytic cells and grows in refrigeration temperatures?

• Mycoplasma hominis
• Mycobacterium leprae
• Clostridium botulinum
• Borrelia burgdorferi
• Listeria monocytogenes

The characteristic most notable regarding the mycoplasmas is that they

• are nonpathogenic.
• are aerotolerant.
• carry out fermentative metabolism.
• produce endospores.
• lack cell walls.

Escherichia coli belongs to the

• green sulfur bacteria.
• spirochetes.
• proteobacteria.
• actinomycetes.
• gram-positive bacteria.

If a patient is diagnosed with a peptic ulcer, which genus of proteobacteria is probably responsible?

• Desulfovibrio
• Helicobacter
• Campylobacter
• Myxococcus

A biological control method to reduce the reproductive success of mosquitoes involves the use of

• Pelagibacter.
• Gemmata.
• Wolbachia.
• Neisseria.
• Acinetobacter.

What is group "c." in the key shown in the figure?

• planctomycetes
• spirochaetes
• fusobacteria
• chlamydiae
• bacteroidetes

Which of the following is NOT a characteristic of spirochetes?

• possess an axial filament
• gram-negative
• helical shape
• easily observed with brightfield microscopy
• found in the human oral cavity

Streptomyces are important because they

• fix nitrogen.
• are strict aerobes.
• make antibiotics.
• are implicated in acne.
• produce conidia.

Staphylococcus and Streptococcus can usually be differentiated by microscope examination because of

• endospore formation.
• cell arrangement.
• acid-fast reaction.
• Gram stain reaction.
• cell shape.

Which gammaproteobacteria are facultatively anaerobic, Gram-negative rods that inhabit the intestinal tracts of humans and other animals?

• Enterobacteriales
• Pseudomonadales
• Legionellales
• Vibrionales

Which of the following photosynthetic bacteria carries out oxygenic photosynthesis and most likely altered Earth's atmosphere by significantly contributing to the accumulation of oxygen gas?

• Cyanobacteria, such as Anabaena and Prochlorococcus
• Purple sulfur bacteria
• Green nonsulfur bacteria such as Chloroflexus.
• Green sulfur bacteria such as Chlorobium

All of the following bacteria are motile. Which does NOT have flagella?

• spirochetes
• Salmonella
• Pseudomonas
• Escherichia
• Spirillum

Salmonella, Shigella, Yersinia, and Serratia are all

• fermentative.
• gram negative aerobes.
• endospore-forming bacteria.
• gram-positive aerobic cocci.
• gram-negative facultatively anaerobic rods.

Gram-positive organisms with high G+C content are in the phylum __________.

• Actinobacteria
• Spirochaetes
• Proteobacteria
• Firmicutes

Which of the following statements about the causative agent of Rocky Mountain spotted fever is FALSE?

• It is in the genus Rickettsia.I
• t is transmitted by ticks.
• It is gram-negative.
• It is an intracellular parasite.
• It is found in soil and water.

Rickettsias differ from chlamydias in that rickettsias

• require an arthropod for transmission.
• are enterics.
• are gram-negative.
• form elementary bodies.
• are intracellular parasites.

All gram-negative bacteria are classified as proteobacteria.

• True
• False

The human body is typically free of archaeal species.

• True
• False

The majority of bacterial species on Earth have not been successfully cultivated.

• True
• False

Currently, no members of Archaea have been linked to human disease.

• True
• False

You have isolated and grown a pure culture of a prokaryotic cell type. The first step in identification is a(n)

• lactose fermentation test.
• flagella stain.
• DNA fingerprint.
• endospore stain.
• Gram stain.

You have isolated an aerobic gram-positive, endospore-forming bacterium that grows well on nutrient agar. To which of the following groups does it most likely belong?

• phototrophic bacteria
• bacillales
• gammaproteobacteria
• deltaproteobacteria
• The answer cannot be determined based on the information provided.

Which of the following pairs is mismatched?

• mycobacteria – acid-fast
• spirilum – aerobic, helical bacteria
• spirochete – axial filament
• enterics – gram-negative
• Pseudomonas – gram-positive

Which of the following best describes the enterics, a bacterial group found primarily in the intestines of humans?

• aerobic, helical bacteria
• gram-negative aerobic rods and cocci
• gram-positive cocci
• endospore-forming rods
• facultatively anaerobic gram-negative rods

Seventeen patients in ten hospitals had cutaneous infections caused by Rhizopus. In all seventeen patients, Elastoplast bandages were placed over sterile gauze pads to cover wounds. Fourteen of the patients had surgical wounds, two had venous line insertion sites, and one had a bite wound. Lesions present when the bandages were removed ranged from vesiculopustular eruptions to ulcerations and skin necrosis requiring debridement. Fungi are more likely than bacteria to contaminate bandages because they

• are aerobic.
• cannot tolerate high osmotic pressure.
• prefer a neutral environment (pH 7).
• have a fermentative metabolism.
• can tolerate low-moisture conditions.

Which of the following statements about algae is FALSE?

• All are unicellular.
• Some are capable of sexual reproduction.
• They produce oxygen from hydrolysis of water.
• They use CO₂ as their carbon source.
• They use light as their energy source.

A definitive host harbors which stage of a parasite?

• larva
• cyst
• adult
• miracidium
• All of the answers are correct.

Trichomonas vaginalis can be distinguished from other parasitic protozoa by which of the characteristics listed below?

• It infects Anopheles mosquitoes and can be transmitted by a bite.
• It has an undulating membrane, infects the vagina, and is frequently transmitted by sexual contact.
• It is usually found in drinking water and is associated with fecal contamination.
• It is a photosynthetic organism that lives in fresh water.

Which of the following statements regarding fungi is FALSE?

• Most fungi are pathogenic for humans.
• Fungi tolerate low moisture conditions.
• Most fungi grow well in acidic culture condition.
• Fungi are eukaryotic heterotrophs.
• Fungi reproduce by forming asexual or sexual spores.

In mid-December, a woman with insulin-dependent diabetes who had been on prednisone fell and received an abrasion on the dorsal side of her right hand. She was placed on penicillin. By the end of January, the ulcer had not healed, and she was referred to a plastic surgeon. On January 30, a swab of the wound was cultured at 35°C on blood agar. On the same day, a smear was made for Gram staining. The Gram stain showed large (10 µm) cells. Brownish, waxy colonies grew on the blood agar. Slide cultures set up on February 1 and incubated at 25°C showed septate hyphae and single conidia. The most likely cause of the infection is a

• protozoan.
• gram-negative bacterium.
• parasitic alga.
• dimorphic fungus.
• yeast.

Which of the following arthropods does NOT transmit diseases by sucking blood from a human host?

• fleas
• mosquitoes
• kissing bugs
• houseflies
• lice

Humans are the definitive host for __________, which is a type of __________.

• Plasmodium; cestode
• Taenia solium; roundworm
• Taenia saginata; tapeworm
• Echinococcus granulosus; tapeworm

Which of the following pairs is mismatched?

• diatoms – petroleum
• dinoflagellates – paralytic shellfish poisoning
• brown algae – algin
• red algae – agar
• green algae – prokaryotic

Which of the following statements is FALSE?

• Fungal spores are used in identification of fungi.
• Fungal spores are highly resistant to heat and chemical agents.
• Fungal spores are for asexual or sexual reproduction.
• Fungi produce asexual spores.
• Fungi produce sexual spores.

Dinoflagellates are a type of unicellular __________. One genus of dinoflagellates is responsible for a foodborne disease called __________.

• fungus; potato blight
• algae; paralytic shellfish poisoning (PSP)
• tapeworm; cysticercosis
• protozoa; dysentery

All of the following are characteristic of algae EXCEPT which ONE of the following?

• Some produce harmful toxins.
• Most are photoautotrophs.
• They are currently classified as plants.
• They may be unicellular or multicellular.
• They mostly live in aquatic habitats.

Three weeks after a river rafting trip, three family members experienced symptoms of coughing, fever, and chest pain. During the rafting trip, the family had consumed crayfish that they caught along the river banks. An examination of the patients' sputum revealed helminth eggs, and serum samples were positive for antibodies to Paragonimus. All of the family members recovered following treatment with praziquantel. In the Paragonimus life cycle,

• both humans and crayfish are intermediate hosts.
• the crayfish are the definitive host and humans are the intermediate host.
• both humans and crayfish are definitive hosts.
• the source of the infection was the river water.
• humans are the definitive host and crayfish are the intermediate host.

Which of the following tends to be more complex in a parasitic helminth than in free-living helminths?

• reproductive system
• digestive system
• nervous system
• digestive and nervous systems

Some species of dinoflagellates produce neurotoxins that cause fish kills and red tides.

• True
• False

If a larva of Echinococcus granulosus is found in humans, humans are the

• reservoir.
• definitive host.
• intermediate host.
• infected host.
• None of the answers is correct.

Which of the following statements regarding protozoa is FALSE?

• Protozoa are unicellular eukaryotes.
• Most protozoa reproduce asexually.
• Nearly all protozoa cause disease.
• Protozoa are common in water and soil.
• Some protozoan pathogens are transmitted by arthropod vectors.

In the malaria parasite life cycle, humans are the ________ host, while mosquitoes are the ________ host as well as the vector.

• intermediate; intermediate
• vector; intermediate
• temporary; final
• definitive; intermediate
• intermediate; definitive

In helminth life cycles, the organism that harbors the adult sexually reproductive phase of the parasite is called the intermediate host.

• True
• False

Dengue fever and Zika virus are transmitted by which of the following?

• fleas
• sucking lice
• mites and ticks
• mosquitoes

Arthropod vectors are blood-sucking animals such as ticks, lice, and fleas that transmit microbial pathogens.

• True
• False

Ringworm is caused by a(n)

• trematode.
• cestode.
• protozoan.
• fungus.
• nematode.

A viroid is a(n)

• capsid without nucleic acid.
• infectious piece of RNA without a capsid.
• infectious protein.
• provirus.
• complete, infectious virus particle.

How do all viruses differ from bacteria?

• Viruses are filterable.
• Viruses are obligate intracellular parasites.
• Viruses do not reproduce.
• Viruses do not have any nucleic acid.
• Viruses are not composed of cells.

Which of the following substances is used for surgical hand scrubs?

• glutaraldehyde
• chlorine bleach
• soap
• chlorhexidine
• phenol

Which of the following events might trigger induction of a temperate bacteriophage?

• Bacterial conjugation
• Normal cell division of an infected cell
• Exposure to UV light
• An infected cell entering the logarithmic phase of growth

How is the lytic cycle different from the lysogenic cycle with respect to the infected host cell?

• The viral DNA may integrate into the host genome during the lytic stage.
• The host cell dies during the lytic stage.
• The host cell is allowed to live during the lytic stage.
• The host cell can only divide during the lytic stage.

What is the fate of the prophage during the lysogenic stage?

• It is copied every time the host DNA replicates.
• It is degraded by the activity of host defense enzymes.
• It is released from the cell by lysing the cell.
• It is packaged into viral proteins and maintained until the host is exposed to an environmental stress.

Most drugs that interfere with viral multiplication also interfere with host cell function.

• True
• False

An envelope is acquired during which of the following steps?

• penetration
• adsorption
• release
• biosynthesis
• uncoating

Which of the following statements about viruses is FALSE?

• Viruses contain DNA or RNA but never both.
• Viruses have genes.
• Viruses use their own catabolic enzymes.
• Viruses use the anabolic machinery of the cell.
• Viruses contain a protein coat.

Which of the following is NOT utilized to culture viruses?

• embryonated eggs
• animal cell cultures
• culture media
• bacterial cultures
• laboratory animals

Some viruses, such as human herpesvirus 1, infect a cell without causing symptoms. These are called

• latent viruses.
• slow viruses.
• lytic viruses.
• phages.
• unconventional viruses.

Which statement is INCORRECT concerning animal viruses?

• Capsid proteins are produced in the cytoplasm.
• Enveloped viruses are surrounded by a lipid and carbohydrate coat, which is made from the host cell's plasma membrane.
• The genome of animal viruses is always single-stranded.
• Retroviruses use an enzyme called reverse transcriptase, which synthesizes DNA using RNA as a template.

________ were first identified in cancer-causing viruses and can induce ________ in infected cells.

• Glycoprotein spikes; syncytia formation
• Oncogenes; transformation
• Herpes viruses; lesions
• T antigens; lysis
• Segmented genomes; reassortment

An example of a persistent viral infection is

• Herpes Simplex Virus infection.
• Human Immunodeficiency Virus infection.
• Varicellavirus infection.
• Hepatitis A infection.
• Influenza.

Which of the following statements is NOT true of lysogeny?

• Lytic cycle may follow lysogeny.
• It causes lysis of host cells.
• It can give infected pathogens the genetic information for toxin production.
• Prophage is inserted into the host genome.
• It is a "silent" infection; the virus does not replicate.

What is the key characteristic of a transformed cell?

• is producing toxins affecting neighboring cells
• has acquired tumor-forming properties
• has undergone chromosomal rearrangements
• is producing budding viruses
• is infected with a lytic virus

Oncogenic viruses

• are lytic viruses that kill the host cell.
• cause acute infections.
• cause tumors to develop.
• have no effect on the host cell.
• are genetically unstable.

Which virus is NOT associated with cancer?

• human papillomavirus (HPV)
• Epstein-Barr virus (EBV)
• hepatitis B virus (HBV)
• coronavirus

Which of the following statements regarding latent viral infections is true?

• During latent infections, small amounts of virus are produced, and virus numbers build up over time.
• Latent viral infections are caused by the slow conversion of cellular glycoproteins from normal to infectious form.
• Latent infections can persist for years in an individual without causing any symptoms.
• Latent viral infections are almost always fatal.

Viruses are the only known infectious agents that are obligatory intracellular parasites.

• True
• False

Shingles is an example of

• reactivation of latent virus.
• transformation.
• persistent virus.
• lysogeny.
• lytic virus.

An infectious protein is a

• viroid.
• prion.
• bacteriophage.
• retrovirus.
• papovavirus.

Which of the following statements concerning prion diseases is true?

• Prion diseases are always inherited.
• Normal host cellular prion proteins (PrP^C) are converted into scrapie proteins (PrP^Sc).
• Prion diseases affect humans but not other animals.
• Prion diseases affect brain function but do not affect the morphology (overall appearance) of brain tissues.

Which of the following is necessary for replication of a prion?

• lysozyme
• DNA
• PrP^Sc
• DNA polymerase
• RNA

A persistent infection is one in which

• viral replication is unusually slow.
• host cells are gradually lysed.
• the disease process occurs gradually over a long period.
• host cells are transformed.
• the virus remains in equilibrium with the host without causing a disease.

What is an oncogene?

• a toxin gene transferred by a virus
• an altered form of a gene that may induce cancer
• a viral polymerase
• a viral ligand found in a family of viruses
• a problematic gene found exclusively in viruses

How are viruses different from eukaryotic cells?

• They do not contain protein.
• They do not contain genetic material.
• They require a host in order to reproduce.
• They do not contain enzymes

What is the function of the structural elements of a virus?

• To provide a source of energy for the virus
• To package and protect the viral genome
• To use all of the cell proteins

A clear area against a confluent "lawn" of bacteria is called a

• phage.
• cell lysis.
• rash.
• pock.
• plaque.

Which statement concerning viral structure is true?

• Spikes are found on some viruses. They are very consistent in structure within a viral species and can be used for identification.
• The proteins in the envelope are capsomeres.
• Animal viruses usually contain tail sheaths and spikes.
• All viruses contain an envelope, which is made of lipid, carbohydrate, and protein.

Part completeBacteriophage replication differs from animal virus replication because only bacteriophage replication involves

• assembly of viral components.
• adsorption to specific receptors.
• replication of viral nucleic acid.
• lysis of the host cell.
• injection of naked nucleic acid into the host cell.

The definition of lysogeny is

• attachment of a phage to a cell.
• when the burst time takes an unusually long time.
• phage DNA is incorporated into host cell DNA.
• lysis of the host cell due to a phage.
• the period during replication when virions are not present.

A virus's ability to infect an animal cell depends primarily upon the

• presence of pili on the host cell wall.
• type of viral nucleic acid.enzymatic activity of a host cell.
• host cell's ability to phagocytize viral particles.
• presence of receptor sites on the cell membrane.

An example of a latent viral infection is

• cold sores.
• mumps.
• subacute sclerosing panencephalitis.
• influenza.
• smallpox.

In which stage is the viral DNA introduced into the cell?

• Assembly
• Release
• Biosynthesis
• Penetration
• Attachment

In which stage does formation of mature viruses occur?

• Attachment
• Assembly
• Penetration
• Release
• Biosynthesis

The host DNA is usually degraded during which stage?

• Release
• Attachment
• Biosynthesis
• Assembly
• Penetration

What would be the fate of a lytic bacteriophage if the host cell died prior to the assembly stage?

• The virus would not be able to infect new hosts.
• The cell could still be revived by the virus.
• The virus would infect new hosts.

Dogs do not get measles because their cells lack the correct receptor sites for that virus.

• True
• False

Why do most scientists agree that viruses are nonliving entities?

• They pass through filters.
• They are composed of relatively simple components.
• They cause diseases in host cells.
• They are not composed of cells.
• They cannot replicate outside host cells.

In the figure, which structure is a complex virus?

• a
• b
• c
• d
• All of the structures are complex viruses.

A viral species is a group of viruses that

• has the same genetic information and ecological niche.
• infects the same cells and cause the same disease.
• has the same morphology and nucleic acid.
• cannot be defined.

Binomial nomenclature is used to name viruses.

• True
• False

Which of the following statements about viral spikes is FALSE?

• They are used for attachment.
• They may cause hemagglutination.
• They are found only on nonenveloped viruses.
• They bind to receptors on the host cell surface.
• They are composed of carbohydrate-protein complexes.

Assume a patient had chickenpox (human herpesvirus 3) as a child. Which line on the graph in the figure would show the number of viruses present in this person as a 60-year-old with shingles (human herpesvirus 3)?

• a
• b
• c
• d
• e

Which of the following is true concerning a lysogenic viral replication cycle?

• Lysogenic infections are similar to persistent infections in that virus is constantly produced.
• Once the lysogenic portion of the cycle has begun, virus is never produced again.
• During lysogeny, the viral genome integrates into the host DNA, becoming a physical part of the chromosome.
• During lysogeny, the viral DNA is present as a circular plasmid.

Assume a patient has influenza. During which time on the graph in the figure would the patient show the symptoms of the illness?

• a
• b
• c
• d
• e