MCB 3023 Exam 4

How do termites obtain nitrogen in their diet?

From nitrogen fixing bacteria in their gut.

From digestion of lignin.

From digestion of cellulose.

From digestion of wood.

From nitrogen fixing bacteria in their gut.

Leghemoglobin produced by plants is important for:

oxygen supply

nodule formation

phosphorous assimilation

acidosis

oxygen supply

Most primary endosymbionts of insects have all these in common, EXCEPT:

are required for survival or fertility

nitrogen fixation genes

highly reduced genomes

maternal transmission

nitrogen fixation genes

What are Zooxanthellae?

Symbionts of tubeworms at hydrothermal vents

Symbionts of ruminants

Heterotrophic symbionts of corals

Photosynthetic symbionts of corals

Photosynthetic symbionts of corals

Lichens contain:

chemolithoautotrophs

a heterotrophic partner and at least one fungal phototrophic partner

at least one fungal heterotrophic partner and at least one phototrophic partner

root nodules

at least one fungal heterotrophic partner and at least one phototrophic partner

Herbivores mostly require microorganisms to help them with the digestion of this compound.

proteins

glycogen

cellulose

starch

cellulose

Humans have a:

rumen fermentation

colonic fermentation

cecal fermentation

stomach fermentation

colonic fermentation

Which of these contains zooxanthellae as photosynthetic symbionts?

tubeworms

termites

corals

lichen

corals

Which genes are encoding for subunits of nitrogenase, the main enzyme for nitrogen fixation?

leghemoglobin genes

nif genes

nod genes

fix genes

nif genes

The majority of Archaea found in the human intestinal tract are _____ .

sulfate-reducing bacteria

sulfide oxidizing bacteria

methanogens

halobacteria

methanogens

The bacterial group that is responsible for root nodule formation in legumes is:

Rhizobia

Rhizospheres

Roseobacter

Rhodobacter

Rhizobia

What is the human microbiome composed of?

Only microbes that live in the intestinal tract of humans.

Only microbes that contribute to the health of humans.

Only microbes that live on human skin.

All microbes that live on or within the human body.

All microbes that live on or within the human body.

When the diet of a ruminant is drastically changed from grass to a starch rich diet, the ruminant may become very ill or die because:

of the production of large amounts of acid, resulting in acidosis.

the microbes in the rumen cannot break down starch.

the starch is broken down very slowly and the rumen becomes clogged.

they lack a source of protein.

of the production of large amounts of acid, resulting in acidosis.

These genes are important for root nodule formation:

nar

nif

nod

nir

nod

What is an endophyte?

A member of the plant root rhizosphere.

A parasite of a plant.

A symbiont that lives inside plant cells.

A parasite of an animal.

A symbiont that lives inside plant cells.

Pathogenicity islands are blocks of genes on the bacterial chromosome that most likely arose from this process.

spontaneous mutation

horizontal gene transfer

chemically induced mutagenesis

vertical gene transfer

horizontal gene transfer

What are the two main functions of B cells?

Activation of MHC and antigen production.

Activation of helper T cells and antibody production.

Activation of antibody cells and cytokine degradation.

Activation of macrophages and endotoxin production.

Activation of helper T cells and antibody production.

How does vertical transmission of a pathogen occur?

From mother to offspring.

By ingesting contaminated water.

As a result of an insect bite.

By an aerosol route.

From mother to offspring.

Exogenous antigen is usually taken up by antigen-presenting cells through phagocytosis, processed, and presented to T cells on their surface by these:

MHC molecules

Tumor necrosis factor alpha

Cytokines

Interleukins

MHC molecules

The Tir/Intimin system of pathogenic E. coli is used for

degradation of SNARE proteins

attachment to host cells

iron acquisition

inhibition of host transcription

attachment to host cells

Which of these is true of an endemic disease?

It is constantly present in a given population.

It is always epidemic on a worldwide scale.

It is present in a population at numbers higher than the ID50.

It is always spread by an animal vector.

It is constantly present in a given population.

All of the following are clinical signs of inflammation at the site of injury EXCEPT:

formation of pus.

constriction of blood vessels.

heat.

swelling.

constriction of blood vessels.

The term for properties of pathogens that aid in causing disease is:

virulence factors

promoters

proteases

pathogenics

virulence factors

Which of these is NOT a mechanism of horizontal gene transfer?

transduction

inherited DNA from mother cell to daughter cell

conjugation

transformation

inherited DNA from mother cell to daughter cell

Some T cells (T lymphocytes):

induce apoptosis of target cells

are macrophages

produce antibodies

induce apoptosis of target cells

Name the type of viral infection in which the viral genome is present in infected cells but the virus only replicates sporadically.

latent

acute

persistent

lytic

latent

Which is an example of innate immunity?

The development of a specific cell mediated response.

The development of a specific antibody response.

The removal of a bacterial cell in the lungs by a resident macrophage.

A quick immune response against an influenza virus because of a previous exposure.

The removal of a bacterial cell in the lungs by a resident macrophage.

Why do RNA viruses have a high mutation rate?

Their RNA is quickly degraded by nucleases.

Their RNA is not methylated after synthesis.

Their RNA contains unusual nucleotides.

Their RNA-dependent RNA polymerases lack a proofreading function.

Their RNA-dependent RNA polymerases lack a proofreading function.

What does a high case-to-infection ratio (CI) indicate?

That the disease is usually fatal.

That most people infected by the pathogen will not develop the disease.

That the disease is usually very mild.

That most people infected by the pathogen will develop the disease.

That most people infected by the pathogen will develop the disease.

The term for the number of NEW cases of a disease within a population during a specific time period is:

incidence rate

mortality rate

prevalence rate

infectious dose 50 rate

incidence rate

An example of a rumen fermenter is the:

rabbit

horse

human

sheep

sheep

What is the electron donor for bacterial symbionts of tubeworms at hydrothermal vents?

carbon dioxide

ferric iron (Fe3+)

oxygen

H2S

H2S

Which of these is characteristic of the enzyme nitrogenase?

It is found in all plant symbionts.

It is found in both prokaryotes and eukaryotes.

It is irreversibly inactivated by oxygen.

It converts dinitrogen to nitrate.

It is irreversibly inactivated by oxygen.

Many of the rumen bacteria specialize in the breakdown of these macromolecules:

proteins

nucleic acids

cellulose polymers

peptidoglycans

cellulose polymers

Camels have a:

stomach fermentation

cecal fermentation

colonic fermentation

rumen fermentation

rumen fermentation

Which of these is true of a mutualistic relationship?

One member benefits and the other member does not receive any benefit.

Neither organism benefits or is harmed by the relationship.

Both organisms benefit.

One member benefits and the other member is harmed.

Both organisms benefit.

All of the following are components that may be used by a pathogen for attachment to a host cell EXCEPT:

cellulases

attachment proteins

capsules

fimbriae

cellulases

Evolution of viruses by reassortment causes dramatic changes to the virus. This is referred to as _____________ .

antigenic drift

transduction

transformation

antigenic shift

antigenic shift

Cytolysins:

are produced by all pathogens

form pores or destroy plasma membranes

help during attachment to the target cell

are endotoxins

form pores or destroy plasma membranes

Which of these results in immunological memory?

The non-specific immune response.

The adaptive immune response.

Passive immunity from mother to offspring.

The innate immune response.

The adaptive immune response.

In order to cause a fast spreading disease, successful infectious pathogens must be able to do ALL of the following EXCEPT:

attach to and/or invade host cells.

kill the host.

evade host defenses.

gain entry to the host.

exit the host.

kill the host

Rhinovirus is a cause of the common cold. What type of infection does it usually cause?

persistent

latent or persistent, with equal likelihood

latent

acute

acute

Pathogens that have the ability to change their surface antigens are better able to do which of the following?

exit the host successfully

enter host cells

evade host defenses

acquire nutrients

evade host defenses

Which one of the following statements is NOT one of Koch's postulates?

Inoculate the isolated microbe into a susceptible host to see if it causes the disease.

Identify and characterize endotoxins from the isolated microbe.

Recover the microbe from the experimentally inoculated host.

Isolate the suspected microbe in pure culture.

Identify the suspected microbe in every person with the disease.

Identify and characterize endotoxins from the isolated microbe.

This is an example of a virus known to undergo evolutionary change by reassortment of genetic elements:

hepatitis type B virus

influenza virus

herpes virus

adenovirus

influenza virus

The term describing a clustering of virulence genes on the chromosome of a pathogenic microbe is:

operon

pathogenicity island

enhancer region

promoter

pathogenicity island

The Ebola virus is transmitted by a ____________ mechanism.

sexual

zoonotic

respiratory

fecal-oral

zoonotic

What is the primary effect of microbial lipopolysaccharides (LPS) on the host?

Acts as a neurotoxin.

Attacks cells of the immune system.

Lyses epithelial cells.

Triggers an intense inflammatory response.

Triggers an intense inflammatory response.

A contagious disease is MOST likely to be spread via:

Sexual transmission

Contaminated medications and dressings

Airborne transmission

Blood-to-blood contact

Airborne transmission