Quizzes Exam 4

Genes encoding _____ are widely used as target genes in molecular biodiversity studies

16S rRNA

Diptheria toxin is a...?

AB toxin

A pediatric patient presents with fever, malaise, and pharyngitis. The neck of the patient is inflamed and described to look like a "bull's neck". Examination of the patient's throat reveals a large grey pseudomembrane extending down the pharynx of the patient. Clinical history of the patient reveals no previous vaccinations. What factor is responsible for the patient's condition?

Diphtheria toxin

Which of the following is the causal agent of gastric ulcers?

Helicobacter pylori

The dose of an antigen that kills 50% of animals in a test group and is used to estimate the virulence of a pathogen known as...?

LD50 (lethal dose 50)

Which of the following pathogens is associated with food borne meningitis in pregnant and elderly patients after ingestion of contaminated vegetables or dairy products such as ice cream and milk?

Listeria monocytogenes

Salmonella enterica serotype Typhi chronic carrier state presents as the result of:

Salmonella dissemination through the bloodstream reaching the gallbladder and establishing long-term infection

A 2-year old patient presents with abrupt oneset localized perioral erythema that later develops into scaled skin syndrome. Which of the following best describes the pathogenesis of this disease?

Staphylococcus aureus secretes exfoliative toxins that split desmosomes in the epidermis resulting in desquamation of the epithelium

A Gram stain prepared from a swab collected from a patient diagnosed with necrotizing fasciitis demonstrated gram-positive cocci arranged in chains. What is the most likely causative agent?

Streptococcus

The rumen is an ______ habitat that depends on _____ to digest cellulose for ruminant animals

anaerobic/cellulolytic and fermentative bacteria

The methodology of microbial ecology includes...?

enrichment and isolation of specific microbes, cell-staining, and characterization of genes, transcripts, and proteins

In a stratified lake, the warmer and less dense layer is called the...?

epilimnion

Staphylococcus aureus is a common causative agent of food borne disease because it...?

grows on many foods, is present in some humans that work in food processing, and produces several heat-stable enterotoxins

A population of metabolically related microorganisms is called a(n)...?

guild

Which of these microorganisms is most likely to be found in the human stomach?

helicobacter pylori

Which approach would help to identify biologically produced sulfur in a sediment sample...?

isotopic fractionation

How does the tetanospasmin affect motor control?

it blocks the release of inhibitory neurotransmitters in the synaptic cleft leading to spastic paralysis

The most heavily colonized human organ by bacteria is the _____, containing 10^11-10^12 bacterial cells per gram

large intestine

The Campylobacter spp. are...?

microaerophiles

Two organisms that both benefit from each other are in a symbiotic relationship called...?

mutualism

Isonicotinic acid hydrazine (INH) is an antibiotic used in the treatment of tuberculosis. It affects the synthesis of...?

mycolic acid

Two major environmental extremes of the deep sea are high _____ and low _____

pressure/nutrient levels

Exotoxins are ____, but endotoxins are ____

proteins/lipopolysaccharide-lipoprotein complexes

The metabolic process of denitrification...?

reduces NO3-

Most nitrogen-fixing bacteria symbiotically associated with plants are called...?

rhizobia

Greenhouse gases...?

such as CO2, CH4, and N2O trap infrared radiation, heating the earth

Which statement is true about the fluid from the hydrothermal vents?

the fluid contains large amounts of reduced inorganic materials

When dealing with stable isotopes of carbon and sulfur, enzymes tend to favor...?

the lighter isotope

Which of the following is true regarding the interaction between hormones and vaginal microbial diversity...?

there is an inverse relationship between estrogen levels and microbial diversity

What is the role of fecal transplants in medicine?

they can provide a healthy microbiota to help treat clostridium difficult infections