QUIZ 3

A disease-causing microorganism or virus is referred to as a(n) pathogen.

Attributes of an organism that promote pathogenicity are called virulence factors.

Fungi that are important for fermentation of fruit secrete degradative enzymes.

Coccidioidomycosis is a fungal disease caused by Coccidioides sp.

An example of genetic variation used in pathogen survival may be changing the pilus type.

Colonization of the body is inhibited by All of the answer choices are correct.

The replicative form of nucleic acid in filamentous phages is positive ssDNA.

Filamentous phages only infect E. coli that have pili.

Phthirus pubis cause "crabs".

Fleas may transmit Yersinia pestis.

Entry of bacteriophages and animal viruses into host cells is by fusion.

For which of the following processes are enzymes not required? Self-assembly

Algae are important environmentally as major producers of oxygen.

Free-floating, photosynthetic organisms found in marine environments are phytoplankton.

Why does abnormal prion protein accumulate in cells while normal prion protein does not? Normal prion proteins are susceptible to protease digestion, while abnormal prion proteins are not.

Fungi are aerobes or facultative anaerobes.

All fungi have chitin in their cell walls

Fungi are classified according to their method of sexual reproduction.

Fungi are important in All of the choices are correct.

Fungi are important because of their ability to All of the answer choices are correct.

Haustoria are specialized hyphae used by parasitic fungi.

Fungi capable of dimorphism grow either as yeast-like or mycelium.

Paralytic shellfish poisoning occurs when humans eat shellfish that have fed on Gonyaulax species.

Gonyaulax produces a non-protein neurotoxin AND is a dinoflagellate.

The "hygiene hypothesis" proposes that lack of exposure to microbes can lead to development of allergies.

Growth of a parasitic organism in or on the host is referred to as infection.

Select the INCORRECT statement about prions. Normal and abnormal prion proteins are found in different types of cells.

How do prions accumulate in brain tissue? Abnormal prion proteins change normal prion proteins into the abnormal form.

The spread of toxin via circulation is called toxemia

If a disease affects only a human and not an animal, then it would be difficult to fulfill Koch's postulate number 2

Cells infected with animal viruses lyse because functions necessary for cell survival are not carried out and the cell dies.

In addition to lysis, animal viruses may exit the host cell by budding.

In the region of budding, the inside of the cytoplasmic membrane becomes coated with matrix proteins.

In the region of budding, the cytoplasmicmembrane acquires spike proteins AND matrix proteins.

The correct order for the stages of a phage infection is attachment, penetration, transcription, replication of nucleic acid and protein, assembly, release.

Phages that can either replicate and cause cell lysis or can integrate their DNA into the host DNA are called temperate phages.

Which of the following is not a characteristic of normal cells grown in vitro in a cell culture? They grow as multiple layers.

Plant viruses enter the host plant via wound sites.

What is a definitive host in the life cycle of a parasite? An organism in which sexual reproduction or the adult form of a parasite occurs.

Please select the INCORRECT statement regarding helminths and the diseases they cause. Some helminths are inadvertently ingested. For example , Onchocerca volvulus, the cause of River blindness, is transmitted by drinking contaminated water or eating fish carrying this parasite.

Prions are made of protein only.

Prions affect the nervous system.

Many protozoa (for example Sarcodina) move by means of pseudopodia.

Protozoans are an important part of the food chain, ingesting large numbers of bacteria and algae.

The genome of retroviruses is made of ssRNA.

Retroviruses are unique in that they use RNA as a template to make DNA.

Protozoan classification used to be based on their means of locomotion.

Sarcodina move by means of pseudopodia.

The most necessary habitat requirement of protozoa is moisture.

Schizogony means multiple fissions AND is performed by protozoa.

The site in a photosynthetic eukaryotic cell where photosynthesis occurs is the chloroplast.

Sexual reproduction in algae involves meiosis that results in the production of gametes with half the amount of DNA as in the parental cells.

One of the organisms that may cause red tide is dinoflagellates.

Single-celled eukaryotic organisms that lack chlorophyll include protozoa AND yeasts.

A more modern equivalent to Koch's postulates is termed molecular postulates.

Species of both Shigella and Streptococcus invade host cells AND produce a toxin.

Prions are an infectious protein.

Spongiform encephalopathy occurs in all of the following EXCEPT plants.

If reasonably pure preparations of virus are available, the number of virus present may be determined by electron microscopy.

The approximate viral concentration of a sample may be determined by quantal

Which is a filamentous phage? M13

The bacterial viruses that are released by a process termed extrusion are called filamentous phages.

The enveloped viruses typically obtain their envelope from the host cytoplasmic membrane as they exit the host.

The best known chronic infection involves hepatitis B.

The chemical nature of endotoxins is that of a/an lipopolysaccharide.

The chemical nature of exotoxins is that of a protein.

Which of the following members of the normal microbiota inhibit the growth of Candida albicans? Lactobacillus species

The composition of the normal microbiota may be affected by All of the answer choices are correct.

Which is/are TRUE of viruses? They may prevent induction of host cell apoptosis.

The damage caused by parasites may be due to all of the following EXCEPTthe parasite's immune response

The common species name of the virus is frequently based on the disease the virus causes.

The family to which the Rhinovirus belongs is the Picornaviridae.

Adhesins are involved in the first step of the infectious process AND are often found at the tip of pili.

The first step in the establishment of infection is that the organism must attach to host cells.

Which of the following factors is not considered important for the establishment of an infection? Toxicity

The lack of susceptibility to diseases of other species in humans may be due to the lack of receptors that are recognized by adherence factors.

Dimorphic fungi may grow as mycelia or yeast AND are often associated with disease in humans.

The pH at which most fungi thrive is 5

A key feature of all viral infections is the separation of viral nucleic acid from the capsid.

The receptors to which animal virus attachment proteins usually bind are glycoproteins.

Fungi are particularly good at infecting plants.

The return of carbon dioxide to the atmosphere and nitrogen to the soil is due to the action of fungi and bacteria.

The connection between a particular organism and a specific disease was first made by Koch.

The series of steps used to connect an organism to a disease are known as Koch's postulates.

One group of animal viruses that are able to agglutinate red blood cells are the orthomyxoviruses.

The site at which a virus has infected and subsequently lysed the infected cell, releasing its progeny to infect and lyse surrounding cells, thereby forming a "clear zone," isa plaque.

The term "segmented" refers to viruses that may contain several pieces of RNA.

The terms helical, icosahedral, and complex refer to shapes of viruses.

In the case of T-even phages, the burst size is about 200 per host cell.

The time from absorption to release for T-even phage is about 30 minutes.

Which of the following BEST describes theprotein coat of a virus? It is called a capsid, protects the nucleic acid, AND is involved in the recognition of host cell receptors by non-enveloped viruses.

The viral envelope closely resembles the eukaryotic cytoplasmic membrane.

Animal viruses are divided into a number of families whose names end in -viridae.

There are ______ major families of DNA-containing viruses that infect vertebrates.7

The phenomenon responsible for the ability of Corynebacterium diphtherium to produce the virulent toxin responsible for the devastating effects of diphtheria is called lysogenic conversion.

Transducing virulent phages do not lyse the cells they invade because bacterial DNA has replaced critical viral DNA in the phage.

Once inside the host cell, phage DNA All of the choices are correct.

Using phages to treat a bacterial infection is an interesting idea because of the increasing problem of antibiotic resistance in pathogens.

Viroids characteristically are composed of ssRNA.

Viroids cause disease in plants.

There are ______ major families of RNA containing viruses that infect vertebrates. 13

Viruses are commonly referred to by their ______ name. disease AND species

Genetic exchange in segmented viruses that allows a zoonotic virus to infect humans is an example antigenic shift.

Viruses are not cultivated in blood agar.

Which of the following does S. pneumoniae use to survive in the host?Capsule

Which of the following would be considered a sign of a disease? A rash (All of these are signs)

Fungal diseases are generally referred to mycoses.

Which statement about aflatoxins is NOT true? They are produced by Candida.

In the replication of phage containing positive-sense DNA, the host's DNA polymerase uses the phage RNA as a template to make negative-sense DNA.

Which statement about most phages that contain single-stranded DNA is NOT true? They contain a negative-sense DNA strand.

Membrane ruffling is induced by some bacteria that trigger rearrangements of a cell's actin, leading to engulfment of those bacteria.

Which statement applies to endotoxins? Toxin is part of the outer cell membrane and has no effect unless released.

Why are viroids resistant to nucleases? Having a circular RNA "genome," they are resistant tomost exonucleases (that digest the free ends of RNA or DNA).

Why is it virtually impossible to eradicatea disease caused by a zoonotic virus? All of the answer choices are correct.

Select the correct sequence for proving Koch's postulates. 2.The microorganism must be present in every case of the disease. 4 .The microorganism must be grown in pure culture from diseased hosts. 3.The same disease must be produced when a pure culture of the microorganism is introduced into susceptible hosts. 1.The microorganism must be recovered from the experimentally infected hosts.

Why was it not possible until recently to use Koch's postulates to show that Treponema pallidum causes syphilis? T. pallidum could not be grown in pure culture.

Nematodes may enter the gastrointestinal tract or the blood.

Why would all protozoa be expected to require large amounts of water in their habitats? Without being in water, they would quickly dehydrate (due to their small size) and

Outside of living cells, viruses are metabolically inert.

A phage that replicates inside the host cell and then lysis its host during its release is a virulent or lytic phage.

The microorganisms that are occasionally found in or on the body are called transient microbiota.

A relationship in which one partner benefits and the other is unaffected is termed commensalism.

The terms yeast, mold, and mushrooms refers to fungal morphology.

A tangle of fungal hyphae is generally known as a mycelium.

Which statement regarding phage replication is TRUE? A lysogen is a bacterial cell with an integrated prophage.

A temperate phage may be lysogenic AND enters a lysogenic or lytic life cycle shortly after entering the host cell.

A limiting factor for viral infection of animals cells is presence of specific receptor molecules on the host cell.

All of the statements about specialized transduction are correct EXCEPT it involves the random transmission of any gene.

The filamentous phages all contain single-stranded DNA.

An exit method used by viruses that does not immediately destroy the host bacterium is extrusion.

Phage-encoded enzymes are produced in a sequential manner AND are used to customize the cell for viral production.

Assembly of the T4 phage may involve some self-assembly AND may involve the use of scaffolds.

C5a peptidase is a virulence factor.

Bacteria may survive phagocytosis by preventing fusion of the lysosome with the phagosome AND lysing the phagosome.

The process by which infectious agents are ingested by host cells is endocytosis.

Bacteria that resist killing by complement proteins are termed serum resistant.

Please select the CORRECT definition for primary endosymbiosis A non-photosynthetic eukaryotic cell engulfs a cyanobacterium, which becomes a chloroplast.

Convergent evolution explains the morphological similarity yet major genetic differences found between slime molds and fungi AND refers to two different organisms that develop similar characteristics in adaptation to similar environments.

Agar is obtained from algae.

Diatoms are algae whse silicon dioxide-containing shells are useful economically as filters.

The nucleocapsid is composed of DNA or RNA, and protein.

Enveloped viruses have a lipid bilayer membrane containing various proteins.

Alga often grow in areas where other forms of life may have difficulty.

Macroscopic algae possess a special structure that acts as an anchor and is commonly called holdfast.

Lichens may be an association of algae and fungi.

Mycorrhizae are vital for the survival of many plants AND increase the absorptive ability of roots.

The changes that occur in virally infected cells are characteristic for a particular virus and are referred to as the cytopathic effect.

Normal tissue taken from animals and prepared immediately as a medium for viral growth is termed a(n) primary culture.

The integration of phage DNA into the bacterial chromosome occurs because of the phage's ability to synthesize an enzyme that integrates its DNA into the host's chromosome.

Once integrated, phage DNA can remain in the prophage state as long as certain phage genes are repressed.

The ability to exist as either a trophozoite or a cyst is characteristic of man protozoa.

One of the greatest causes of human deaths through time has been due to Plasmodium species.

If you had three tubes of flu viruses and you exposed tube 1 to protease, tube 2 to proteaseand RNase,and tube 3 to protease and DNase, and the contents of tube 2 were be degraded, you would be able to conclude that an RNA virus.

What are the plaques in the plaque assay? Areas where all of the host bacteria have died.

Which statement regarding protozoa is INCORRECT? The infectious form of some protozoa is the trophozoite.

What do hemoflagellates have in common with bacteria? They divide by binary fission.

What are two ways that phage can replicate without directly lysing their host cell? Extrusion and lysogeny

What is a defective phage? A virus that has lost some of its genetic material, and therefore cannot replicate within a new target cell.

One of the most intensively studied virulent phages which infects E. coli is T4

What part of the E. coli T4 phage attaches to the host cell receptors? Protein fibers at the end of the phage tail. C

Resistance of some animals to certain viral diseases is based on lack of specific receptors on the host cell.

When a non-enveloped animal virus adsorbs to the host cell with its protein spikes, the virions are taken into the cell by the process of endocytosis.

Convergent evolution explains the morphological similarity yet major genetic differences found between slime molds and fungi AND refers to two different organisms that develop similar characteristics in adaptation to similar environments.

When cellular slime molds run out of food, they form a slug.

Pediculus humanus only uses humans as a host AND can transmit a bacterial disease.

Which are not arthropods? Flukes

Which of the following is FALSE about mycoses? They are diseases caused by protozoa.

Which group has chitin in the cell walls? Fungi

The activation of the SOS system in a bacterium infected with a prophage results in destruction of the viral repressor through host protease activity AND lysis of the bacterial cell.

Which is true of lysogenized cells? They are immune to infection by the same virus AND may have new properties.

Please select the INCORRECT statement regarding eukaryotic toxins. Red algae produce the toxin corraline.

Which of the following about helminths is TRUE? Cestodes do not have a digestive system; they absorb predigested nutrients from the host through their skin.

Which of the statements regarding Naegleria fowleriis FALSE? It is a small, Gram-negative, flagellated diplococcus.

Which of the following are characteristics of fungi? Their cell wall contains chitin AND theyuse nutrients from dead or decaying organic matter.

How does Ascaris lumbricoides, an intestinal parasite, cause choking and pulmonary symptoms in some people? Ingested Ascarislarvae penetrate intestinal capillaries, from where they are carried to the lungs, causing coughing and shortness of breath.

Which of the following are diseases caused by protozoa Giardiasis, malaria, AND toxoplasmosis.

Why would it be more difficult to treat diseases in humans caused by members of the Eukarya than diseases caused by the Bacteria? Eukaryotic microbes use many of the same enzymes and systems as humans, so we lose the ability to target certain molecules that might be present ONLY in the cell type we want to eliminate.

Which of the following definitions is CORRECT? Saprophytes—organisms that take in nutrients from dead and decaying matter.

Select the FALSE statement regarding protozoa. All protozoa contain mitochondria.

Which of the following fungi is mismatched with the type of infection it causes? Pneumocystis jirovecii - systemic

Why does conidia formation increase when food supplies of a fungus are diminishing? Spores help the fungus survive under poor conditions such as a low food supply until conditions improve.

Which of the following is NOT an algal pigment? Bilirubin

Select the TRUE statement regarding algae.Although most algae have a cellulose/pectin cell wall, some algae lack a cell wall.

Which of the following is NOT an economic importance of fungi? Fungi may form symbiotic relationships with algae

Newborn babies acquire microbiota All of the above are a source of microbiota.

Which of the following is NOT true about the role normal microbiota plays in maintaining host health? They inhibit the innate immune system.

Plant viruses may be transmitted by All of the choices are correct.

Which of the following is NOT true of prions? Prions that cause spongiform encephalopathies have a different amino acid sequence from PrP c.

Which is NOT a mechanism by which viruses avoid the immune system? Inducing an overproduction of cytokines, causing a cytokine storm.

Which of the following is an example of damage caused by inflammation? Glomerulonephritis - resulting from activation of complement system proteins.

Which is true about superantigens? They are a type of exotoxin AND they stimulate an abnormally high number of T H cells.

Which of the following is/are true about endotoxins? Lipid A is the toxic portion of the molecule.

Which of the following statements regarding protozoa is FALSE? All protozoa lack All protozoa lack mitochondria.

Which of the following statements regarding tapeworms is FALSE They complete their life cycle in a single host.

Virulent pathogens are more likely to cause severe disease.

Which of the following would NOT be considered virulence factor(s)? Ribosomes