Microbiology Final Exam (Mcgraw-Hill) ch 10,5,11,20, 6
Which of the following are physical ways to remove or destroy microbes?
Incineration Filtration Ultraviolet radiation Autoclaving
______ provides an alternative to heat for sterilization and disinfection, but the process damages some types of plastics.
Irradiation
______ is a revolutionary new technology being used in clinical labs that can rapidly identify an organism based on its protein profile.
MALDI-TOF mass spectrometry
You are working in a clinical lab and are given a stool sample to analyze for suspected roundworms. What phenotypic characterization approach would give you the fastest presumptive answer?
Microscopic morphology
Choose the methods used to identify prokaryotes that are based on phenotypic characteristics.
Microscopic morphology Culture characteristics Metabolic capabilities
A reason why environments that are routinely exposed to O2 can support anaerobic growth is that ______.
O2-consuming organisms depletes the oxygen levels
Which of the following use moist heat to destroy microbes?
Pasteurization Pressurized steam Boiling
It is often difficult to choose which germicide to use because often the most effective options ______.
are not the safest
According to the rules of nomenclature, the name of a bacterium or archaeon ______.
can reflect the habitat of the organism can honor a scientist needs to include a Latin suffix
Sulfur-oxidizing bacteria ______.
can sometimes grow in filaments can use hydrogen sulfide or thiosulfate as an energy source
Adding sorbic, propionic, and benzoic acid to foods affects ______ of microbes.
cell membrane function
High pressure (130,000 psi) is thought to kill microbes by altering their ______.
cell membranes proteins
Choosing the correct antimicrobial procedure depends on many factors including ______.
composition of item type and number of microbes environmental conditions
A surgical scalpel is rated as a ______ instrument because it penetrates skin and mucous membranes and therefore must be sterile.
critical
Members of the Gram-negative genera Aquifex and Hydrogenobacter are hydrogen-oxidizing bacteria. An example of their metabolism involves using ______.
hydrogen as a source of energy and oxygen as a terminal electron acceptor, forming water
Salting and drying decrease the availability of water in food, resulting in an environment that is ______ relative to microbes, thereby preventing their growth.
hypertonic
Ozone ______.
is a strong oxidizing agent
Ethylene oxide is gaseous agent that ______.
is very useful for sterilizing heat- or moisture-sensitive items
Adding preservatives such as benzoic acid to food is important because ______.
it inhibits growth of many bacteria and mold
Microscopic morphology, culture characteristics, and fatty acid analysis are all examples of ______ characteristics used to identify prokaryotes.
phenotypic
The evolutionary relatedness of organisms is called
phylogeny
What term describes the evolutionary history of organisms?
phylogeny
Heat treatment, irradiation and filtration are examples of ______ used to control microorganisms.
physical processes
Ecophysiology is the study of the ______.
physiological mechanisms bacteria and archaea use to live in terrestrial and aquatic environments
A high-solute environment damages microbial cells by causing ______.
plasmolysis
The act of delaying spoilage is ______.
preservation
High- _ processing (HPP) is used to decrease the number of microbes in food while maintaining the color and flavor.
pressure
The _ bacteria have projections called prosthecae, which are extensions of the cytoplasm and cell wall that increase the surface area to facilitate absorption of nutrients.
prosthecate
The purpose of the sheath in sheathed bacteria is for ______.
protection
When boiling or pasteurizing a sample, microorganisms are destroyed because their ______.
proteins are irreversibly denatured
Which four of the following microbial groups are the most resistant to chemical control methods?
protozoan cysts and oocysts bacterial endospores nonenveloped viruses Mycobacterium species
MALDI-TOF mass spectrometry is an important new technology in bacterial identification because it can identify an organism from a colony ______.
rapidly, often in less than 15 minutes based on the profile of its proteins
All of the following are examples of biochemical tests EXCEPT one. Which? Multiple choice question. catalase serology gelatinase oxidase sugar fermentation
serology
Scientists group bacteria into different groups in order to ______.
show how different species are related
Microscopic examination is important in the presumptive identification of an organism because it can provide information on the organism's ______.
size and shape staining characteristics
The main effect of low temperature storage is to ______.
slow the activity of microbes
All of the following are examples of electromagnetic radiation EXCEPT ______. Multiple choice question. microwaves UV light X-rays sound waves visible light
sound waves
The motile cells found in sheathed bacteria are called ______ cells, and these exit through the end of the sheath.
swarmer
True or false: Scientists sort living organisms into different groups to show the relationships among the species
t
True or false: Some methods of detecting specific nucleotide sequences make it possible to identify organisms that cannot yet be grown in culture.
t
True or false: The risk of developing a fatal infection after surgery has substantially decreased since the late 19th century because modern hospitals now have procedures in place to avoid microbial contamination.
t
_ is the science that studies organisms in order to arrange them into groups; it can be viewed as three separate interrelated areas: identification, classification, and nomenclature.
taxonomy
Bacteria are given names according to internationally recognized rules based on which of the following?
the International Code of Nomenclature of Prokaryotes
All of the following are reasons why sequencing the genes of small subunit (SSU) rRNA is extremely useful in classifying organisms EXCEPT ______. the genes are often horizontally transferred some sequences in groups of organisms that diverged a long time ago will still be similar their genes are of moderate size even organisms that cannot be grown in culture can be classified
the genes are often horizontally transferred
Bacteria that oxidize sulfur are Gram-negative rods or spirals that ______.
use sulfur compounds as an energy source and oxygen as a terminal electron acceptor
Germicidal chemicals ______.
usually react irreversibly with proteins, DNA, cytoplasmic membranes, or viral envelopes are often poorly understood with regards to mechanisms of action
Chlorine-releasing compounds such as sodium hypochlorite (bleach is a 5.25% solution) are used for all of the following EXCEPT ______. Multiple choice question. sewage and waste water disinfection food equipment sanitation swimming pool treatments household cleaning wound treatment and skin cleansing
wound treatment and skin cleansing
You have a sample containing bacteria that cannot yet be grown in culture. You decide to use 16s rDNA sequences to identify the bacteria. What is the correct order of steps you should use? Start with the earliest at the top.
1. extract DNA from the bacteria 2. amplify the bacterial DNA 3. sequence the 16S rDNA 4. compare the 16S rDNA sequence with sequences of known organisms
What method are researchers today most likely to use in order to group organisms into a classification scheme?
16S rDNA sequence data
Aqueous solutions of alcohol at a concentration of ______ are more effective than 100% alcohol.
60-80%
When two prokaryotic strains are compared by DNA hybridization, what is the minimum percent similarity they need to show to generally be considered members of the same species?
70%
_ species are Gram-negative curved rods that are highly motile and prey on other Gram-negative rods by boring a hole in their cell wall.
Bdellovibrio
Controlling microbial growth is important in which of the following scenarios? esting a water sample for bacterial contamination Caring for an open wound Manufacturing of food products Preparing a patient for surgery
Caring for an open wound Manufacturing of food products Preparing a patient for surgery
_ media are designed to reveal specific colony characteristics that can help in the initial identification of bacteria in clinical samples.
Differential
_______ does not actually destroy microbes or inhibit their growth but instead removes them physically from samples.
Filtration
_______ is a physical means used for destroying or removing microorganisms.
Filtration
The base ratio of an organism is usually expressed as the percent of guanine plus cytosine, which is called the _ content.
G+C
You sequence the genome of an organism and measure the relative amount of each nucleotide. After measuring the percent of cytosine at 20%, what can you safely conclude about the percentages of the remaining nucleotides?
Guanine is 20%; adenine and thymine are each 30%.
Taxonomy can be viewed as three separate but interrelated areas. Match these three areas with their definitions. Classification Identification Nomenclature
Identification matches Choice Process of characterizing an isolate to determine the group (taxon) to which it belongs Classification matches Choice Process of arranging organisms into similar or related groups, primarily to make it easier to identify and study them Nomenclature matches Choice System of assigning names to organisms
Which of the following strategies is least important when attempting to identify the causative agent of a patient's disease symptoms?
Identifying each and every organism present in the patient or patient's sample.
______ is the destruction of microbes by subjecting them to extremes of dry heat, reducing them to ashes.
Incineration
Consider the use of low temperature storage for the preservation of food. Which of the following are accurate statements? Multiple select question. Psychrotrophic and some psychrophilic microorganisms can grow at refrigeration temperatures. The ice crystals that form during freezing kill microbial cells, making this an effective method of sterilizing food. Refrigeration inhibits the growth of many pathogens and spoilage microorganisms by slowing or stopping critical enzyme reactions.
Psychrotrophic and some psychrophilic microorganisms can grow at refrigeration temperatures. Refrigeration inhibits the growth of many pathogens and spoilage microorganisms by slowing or stopping critical enzyme reactions.
Choose the correct descriptions of serological tests.
Require detection by antibodies. Rely on differences of surface structure molecules such as components of the cell wall, capsule, flagella, or pili.
Why are ribosomal components (ribosomal RNA and ribosomal proteins) considered reliable indicators of evolutionary relatedness?
Ribosomal genes are not commonly horizontally transferred. Ribosomes perform crucial and functionally constant tasks. Ribosomes are present in all organisms.
_ testing uses antibodies to detect characteristic proteins or polysaccharides that make up microorganisms.
Serological, Serotyping, or Serologic
Colony morphology can give hints as to the identity of the organism. Match the following examples of specific morphological features with the correct organism. Serratia marcescens Pseudomonas aeruginosa Streptococcus pyogenes
Serratia marcescens matches Choice often red when incubated at 22oC Pseudomonas aeruginosa matches Choice has a distinct fruity odor; often produces a soluble greenish pigment Streptococcus pyogenes matches Choice forms β-hemolytic colonies on blood agar
When comparing phenotypic and genotypic methods of classification of organisms, which of the following best describe phenotypic methods?
Some taxonomists believe classification should be based on more than just genotypic traits. Classification schemes that group organisms by phenotype have been largely replaced by DNA sequencing data. Phenotypic methods still provide an important foundation for prokaryotic identification.
______ destroy all microbes, including viruses and endospores.
Sterilants
When comparing two organisms using DNA hybridization, the process relies on what property of DNA?
The extent of hybridization reflects the degree of sequence similarity between the two organisms. Select a concept reso
What is one disadvantage of using heat treatment to sterilize plastic items?
The items may melt.
Which of the following is a major advantage of detecting specific nucleotide sequences to identify prokaryotes?
The organisms do not need to be grown in culture.
Why are sequences of ribosomal RNA so useful in microbial classification and identification?
They allow identification without culturing the organism. Once a sequence is determined, it can be compared with sequences of known organisms by searching extensive databases. The sequences are relatively stable, since the ribosome would not function with too many mutations.
Which of the following accurately describe biochemical tests used to identify microorganisms?
They generally provide a more certain identification than just relying on colony morphology. They rely on differences in metabolic capabilities of microorganisms.
Which of the following chemical classes destroy microorganisms by forming chemical bonds that cross-link and inactivate proteins and nucleic acids?
aldehydes
A sterile object is free of ______.
all viable microorganisms and viruses
Bdellovibrio species ______.
are highly motile Gram-negative curved rods bore a hole in the cell wall of their prey prey on Gram negative bacteria like E. coli
Radio waves, X-rays, microwaves, UV light and gamma rays are all examples of ______.
electromagnetic radiation
The most highly resistant microbial structure is the bacterial
endospore
Like the green and purple bacteria, members of the genus Heliobacterium are also examples of anoxygenic phototrophs. They are ______ bacteria related to members of the genus Clostridium.
endospore-forming rod-shaped Gram-positive
_ oxide is an extremely useful gaseous sterilizing agent that destroys all microbes and is often used to sterilize fabric, equipment, and implantable devices.
ethylene
True or false: Choosing which germicide to use is not that complicated since we only consider how effective it is against the target microbes.
f
True or false: Scientists now understand the true diversity of microbial life and have determined the relationships between the millions of prokaryotes that exist.
f
True or false: There is a standard antimicrobial procedure available from the Centers for Disease Control and Prevention (CDC) that can be used for all different microorganisms under any condition.
f
Prosthecate bacteria form projections called prosthecae, which are extensions of the cytoplasm and cell wall. These prosthecae ______.
facilitate absorption of nutrients
The straining of a fluid or air through a membrane to trap microorganisms is known as
filtration or filtering
Chlorine and iodine are common disinfectants that belong to a class of chemicals called
halogens
Prokaryotes that grow well in an environment that contains 32% NaCl would be called extreme
halophiles
Match the examples given to the type of method used to control microbial growth. heat treatment, filtration, irradiation antimicrobial chemical
heat treatment, filtration, irradiation physical method of control antimicrobial chemical chemical method of control
Disinfectants that destroy all viruses and vegetative organisms but not endospores are referred to as _ -level disinfectants.
high
All of the following are characteristics of bleach, a solution of sodium hypochlorite, EXCEPT ______? Multiple choice question. it reacts with some organic compounds to form carcinogens its germicidal activity is disrupted by organic compounds it is only effective against a limited range of microorganisms it is corrosive and toxic it is irritating to skin and mucous membranes it reacts with some organic compounds to form trihalomethanes
it is only effective against a limited range of microorganisms
Although generally less reliable than heat, germicidal chemicals are especially useful for treating ______.
large surfaces heat-sensitive items
Microorganisms that are free living are ______ to chemical disinfectants than microorganisms in a biofilm.
less resistant
Choose the pair of phrases that best completes the following scenario: Consider two organisms that diverged from a common ancestor at some point in history. If there are many differences in the sequences of their DNA, this indicates they diverged ______: if there are few differences, this indicates they diverged ______.
longer ago; more recently
A solution of sodium hypochlorite is more effective against bacteria at _______ pH.
low
Soap generally does not destroy most microbes, but it aids in their ______.
mechanical removal
Household bleach applied at 55C is ________ effective in killing bacteria than if it were applied at 50
more
Many cyanobacteria can convert nitrogen gas (N2) to ammonia, which is a process called ______.
nitrogen fixation
Halogens are highly reactive _______ agents that _______.
oxidizing; cause damage to proteins
Used as an alternative to chlorine for disinfecting water, _ is a strong but unstable oxidizing agent that must be generated on-site, usually be passing air or O2 between two electrodes.
ozone or O3
When selecting an appropriate chemical disinfectant, it is important to realize that the death rate is significantly influenced by ______.
pH temperature