UF MCB 3020 Exam 4

Which of the following can be examined with an ordinary bright-field microscope?

Wet mounts

Heat-fixed specimens

Chemical-fixed specimens

All of the choices are correct.

All of the choices are correct.

The most common method used by clinical microbiology labs for identifying bacteria are _________.

biochemical

Which of the following tests can be used to distinguish Escherichia from Enterobacter?

IMViC

Chlorination of water supplies represents an epidemiological technique directed at ________.

eliminating sources of infection

Standard microbiological practices include all of the following EXCEPT _________.

hair longer than shoulder length should be tied back

work space should be disinfected only when contaminating spills occur

eating, drinking, manipulation of contact lenses, and the use of cosmetics, gum, and tobacco products are strictly prohibited in the lab

lab personnel should know how to use the emergency eyewash and shower stations

work space should be disinfected only when contaminating spills occur

The most common types of healthcare-associated infections are _________.

urinary tract infections

The ______ rate refers to the total number of individuals infected at any one time regardless of when the disease began.

prevalence

_______ are the leading cause of healthcare-associated diseases.

Bacteria

The ______ rate is the relationship of the number of deaths from a given disease to the total number of cases of the disease.

mortality

A(n) _______ is an increase in disease occurrence within a large population over a very wide region (usually the world).

pandemic

Chlorination alone will usually suffice to inactivate viruses present in drinking water. T/F

False

Which of the following represents ways in which canned foods may undergo spoilage?

All of the choices are correct.

As a result of underprocessing during canning

Leakage of contaminated water through can seams during cooling

Spoilage before canning

All of the choices are correct.

Which of the following represents a different principle for food preservation?

Heating

Penicillin is produced by some _________.

fungi

Indicator organisms are added to drinking water to test whether the purification process is being carried out effectively. T/F

False

Potable water is unfit for consumption or recreation because of the high levels of microbial contaminants present. T/F

False

Pasteurization of milk _________.

usually eliminates all disease-causing organisms

All of the following are responsible for food safety EXCEPT _______.

There are no exceptions here. All parties listed are responsible.

Water reuse is the purification of wastewater so that it can serve as drinking water. T/F

True

What did Fredrick Griffith do?

Described bacterial transformation

What did Louis Pasteur do?

disproved spontaneous generation

What did Edward Jenner do?

discovered vaccine for smallpox

What did John Snow do?

Determined the source of a cholera outbreak

A microbe is discovered living in an extreme environment near a deep sea vent. The microorganism lacks a nucleus and peptidoglycan in its cell wall, but it does have unusual membrane lipids. This species is most likely a member of the Domain _________

Archaea

Which of the following experiments is used to identify new pathogens?

Koch postulates

What is bound to the rough endoplasmic reticulum that makes it different from the smooth endoplasmic reticulum?

Ribosomes

Carl Woese distinguished between the members of the Archaea and the Bacteria using studies of their _________

Ribosomal RNA

The term used to describe bacteria that have a spherical shape is _________

Coccus

The study of viruses is known as _________

Virology

Antiseptic surgery was pioneered by _________

Joseph Lister

Chemotaxis is a process by which bacteria _________

move toward an attractant or away from a repellent

An external structure unique to archaea are the _________

cannulae

Which of the following is not true about archaeal ribosomes?

They have similar antibiotic sensitivities to those of bacteria.

Unlike members of domain Bacteria, most archaeans have linear chromosomes. T/F

False

Cells with a relatively complex morphology that have a true membrane-delimited nucleus are called _________

eukaryotes

All of the following statements about the periplasmic space are true except _________

a minimal periplasmic space may be observed between the plasma membrane and the peptidoglycan in some Gram-positive bacteria

it is located between the plasma membrane and outer membrane of Gram-negative bacteria

it contains hydrolytic enzymes and binding proteins involved in nutrient acquisition

it is found only in Gram-positive bacteria

it is found only in Gram-positive bacteria

The term used to describe bacteria that are intermediate in shape between spherical and rod-shaped is _________

coccobacilli

Cell walls of most archaea and bacteria contain peptidoglycan. T/F

False

Some archaea have been observed to form tubelike structures with tiny grappling hooks at the ends. These tubelike structures are called _________

hami

Which of the following is a function of the mitochondrion?

ATP synthesis

Tricarboxylic acid cycle enzyme reactions

Electron transport

All of the choices are correct.

All of the choices are correct.

Cells may enter stationary phase because of _________

the depletion of an essential nutrient

All of the choices are correct.

a lack of available oxygen

the accumulation of toxic waste products

All of the choices are correct.

The length of the lag phase of growth can vary depending on _________

the condition of the microorganisms

the temperature

the nature of the growth medium

All of the choices are correct.

All of the choices are correct.

Which of the following is a reason for the occurrence of a lag phase in a bacterial growth curve?

The medium may be different from the previous growth medium so that the cells must synthesize new enzymes to use different nutrients.

The organisms may have been injured and require time to recover.

The cells may be old and depleted of ATP, essential cofactors, and ribosomes that must be synthesized before growth can begin.

All of these are potential reasons.

All of these are potential reasons.

Which microbial control method best describes how an autoclave sterilizes material?

By heat

When counting isolated colonies on an agar plate, it is generally assumed that each colony resulted from one, original cell. T/F

True

Plasmids that have genes that decrease bacterial susceptibility to antibiotics are called _________blank factors.

resistance

Why would it be beneficial for cells to wait until a critical population density is reached before expressing certain genes?

Without a certain density, it would be highly unlikely that the molecules produced by a cell in the group could find and bind to other cells of the population effectively.

Genes for antibiotic resistance can be found in antibiotic-producing bacteria as well as in non-antibiotic-producing bacteria. T/F

True

A _________blank mutation does not alter the amino acid sequence of the resulting protein.

Silent

The site on the DNA to which a repressor protein binds is the _________

operator

Transfer of genes from one mature independent organism to another is called _________

horizontal gene transfer

Mutations that result in the death of an organism when expressed are called _________ mutations.

lethal

In eukaryotes, the initiator tRNA for translation is _________

Met−tRNAiMet, which is also used by archaea

Which of the following types of mutation may play an important role in driving evolution because they are often nonlethal and, therefore, remain in the gene pool?

Missense

The enzyme _________blank unzips and unwinds the DNA molecule.

helicase

Which of these techniques sterilizes on the basis of the size of the microbes to be removed?

Filtration

Which of the following methods of genetic recombination is common to both eukaryotic and bacterial cells?

Vertical gene transfer

This term refers to a microbe establishing itself and multiplying on a body surface

Colonization

This term refers to a microbe that causes disease only when the body is already compromised in some way

Opportunistic pathogen

This term refers to the degree of pathogenicity (disease causing ability) of a microbe

Virulence

This term refers to a microbe that causes disease in otherwise healthy individuals

Primary pathogen

Because you have always been fascinated by spiders and bacteria, you decide to study the microbiome of a species of spider that is locally abundant. You are able to cultivate many bacteria from the spiders gut in the lab, and the spiders do not appear to be negatively affected by treatment with antibiotics that you know will inhibit the growth of these bacteria. Based on this evidence, which of the following types of symbiotic relationships do you suspect might be occurring between the spider and the bacteria?

Cooperative

In general, as genome size of organisms increase, the metabolic and morphological complexity of the cell _________

increases

Tears protect the eyes by _________

flushing and lysozyme

The innate response resists a particular foreign agent; moreover, innate immune responses improve on repeated exposure to the agent. T/F

False

Inflammation is a nonspecific defensive reaction to a tissue injury. T/F

True

Patients who take antibiotics sometimes experience overgrowth of the fungus Candida albicans in their mouths and throats (a condition called thrush). C. albicans is considered part of the gastrointestinal microbiome but its population is typically limited by the presence of other microorganisms. Based on this evidence, which of the following types of symbiotic relationship do you think occurs between members of the normal flora and C. albicans?

Competition

Which of the following is considered to be a biological defense mechanism?

Gastric acid

Fever

Normal microbiota

Skin

Normal microbiota

Bacteria within biofilms exchange _________

plasmids

nutrients

quorum-sensing molecules

All of the choices are correct.

All of the choices are correct.

The skin surface is a very favorable environment for colonization by most microorganisms. T/F

False

The inhalation of cigarette smoke and similar pollutants has a gradual effect on cilia lining the respiratory tract, first causing the beating to slow and eventually stop. How does this change in cilia most directly impact the resistance mechanisms of the host?

Innate host immunity due to mechanical barrier protection would be lost

A _________ epidemic is characterized by a sharp rise to a peak then a rapid, but not as pronounced, decline in the number of individuals infected.

common-source

Which of the following is used to reduce or eliminate the source of an infection?

All of the choices are used to reduce or eliminate the source of an infection.

Treatment of sewage to reduce water contamination

Destruction of vectors by spraying insecticides

Destruction of an animal reservoir of the infectious agent

All of the choices are used to reduce or eliminate the source of an infection.

Chlorination of water supplies represents an epidemiological technique directed at _________

eliminating sources of infection

Which type of epidemic usually results from the introduction of a single infected individual into a susceptible population?

Propagated

The natural site or environmental location in which the causative organism is normally found is called the _________

reservoir

The _________ rate is the relationship of the number of deaths from a given disease to the total number of cases of the disease.

mortality

Which of the following terms refers to a disease that maintains a relatively steady, low-level frequency at a moderately regular interval?

Endemic

Consider a community in which the vaccination rate for measles is 99 percent. A 2-year-old with leukemia, has not received the measles vaccination because of their immunocompromised status. The child is unlikely to get measles because _________

there is substantial herd immunity in his community

Consider the following hypothetical situation. Researchers doing influenza surveillance involving molecular analysis of recent isolates of the virus notice a major change in the H and N antigens. What is a likely outcome?

The number of cases of influenza will increase significantly.

The first case in an epidemic is called the _________ case.

index

Javier buys a package of fresh-sliced ham from the deli and places it in his refrigerator. Unbeknownst to him, there are 10,000 E. coli cells on his ham. After three days under refrigeration, predict the number of E. coli cells that would be on his ham, using what you know about the effects of refrigeration on most microbes.

Slightly more than 10,000

The main environmental factors that affect microorganism growth include chemical inhibitors, oxygen, pH, nutrients, moisture, and _________

temperature

With ideal environmental factors, the reproduction rate of many bacterial species is _________

extremely rapid

Above 100°C (212°F) most bacteria _________

are destroyed

At freezing temperatures, most bacteria _________

stop growing, but are not dead

Check all of the following that showcases how microbes can be used by people.

Production of breads

Production of cheeses

Production of antibiotics

Production of vitamins

Production of enzymes used for many different industrial applications

All of them showcase how microbes can be used by people