Microbiology Exam I

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Microbiology @ UML 2012

Organisms that can grow in habitats with low water activity by maintaining a high internal salt concentration are called __________ organisms.

osmotolerant

Organisms that require high levels of sodium chloride in order to grow are called __________ organisms.

halophilic

Organisms that have their optimum growth pH between 0.0 and 5.5 are called __________.

acidophiles

Organisms that have their optimum growth pH between 5.5 and 8.0 are called __________.

neutrophiles

Organisms that have their optimum growth pH between 8.5 and 11.5 are called __________.

alkaliphiles

Organisms that grow best at pH levels above 10 are called __________ __________.

extreme alkaliphiles

Organisms with growth temperature maxima between 85 and 113°C are referred to as __________.

hyperthermophiles

Complex microbial communities that grow tightly adhered to surfaces are called __________.

biofilms

Microbial __________ is an increase in cell constituents that may or may not be accompanied by an increase in cell number.

growth

An open system in which the growth rate is maintained by the removal and addition of media at such a rate as to maintain a constant cell density is called a

Culturostat

In a continuous culture system, the rate at which media is added and removed is called the __________ rate.

Flow-through

Organisms that grow well at 0°C and have optimum growth temperatures of 15°C or lower are called

Psychrophiles

Organisms that grow at 0°C and have a maximum growth temperature of 35°C are called

mesophiles

Organisms that do not require oxygen for growth but grow better in its presence are called

facultative anaerobes

Organisms that ignore oxygen and grow equally well in its presence or absence are called

aerotolerant

Organisms that are damaged by the normal atmospheric levels of oxygen (20%) but require oxygen at levels of 2-10% for growth are called

microaerophiles

The membranes of psychrophilic bacteria have relatively high levels of __________ fatty acids, which allow them to remain semi-fluid at cold temperatures.

sterol

Organisms that are not drastically affected by increased pressure are called

barotolerant

Most microorganisms maintain their internal pH

near their optimal growth pH

The cell wall of bacteria constrains the ___________ _________ that results from the osmolarity of the cytoplasmic contents.

Turgor pressure

The site at which replication of DNA starts in bacterial cells is known as the __________ of ___________.

origin; replication

The __________ __________ is the length of time it takes for a population of microorganisms to double in number.

generation time

Growth is said to be __________ when all cellular components are synthesized at constant rates relative to one another.

balanced

Organisms that can grow in habitats with low water activity by maintaining a high internal salt concentration are called __________ organisms.

osmotolerant

Organisms that have their optimum growth pH between 0.0 and 5.5 are called __________.

acidophiles

Organisms that have their optimum growth pH between 5.5 and 8.0 are called __________.

neutrophiles

Organisms that have their optimum growth pH between 8.5 and 11.5 are called __________.

alkaliphiles

Organisms that grow best at pH levels above 10 are called __________ __________.

extreme alkaliphiles

Organisms with growth temperature maxima between 85 and 113°C are referred to as __________.

hyperthermophile

Complex microbial communities that grow tightly adhered to surfaces are called __________.

biofilms

Microbial __________ is an increase in cell constituents that may or may not be accompanied by an increase in cell number.

growth

If all cell components are synthesized at constant rates relative to one another, the culture is said to be in __________ growth; however, if the rates of synthesis of some components change relative to the rates of synthesis of other components, the culture is said to be in __________ growth.

balanced;unbalanced

The purpose of the penicillin binding proteins is to link phospholipids together in the cellular membrane.

False

When a young, vigorously growing culture of bacteria is transferred to fresh medium of different composition, the lag phase is usually short or absent.

False

The growth rate of a given species of microorganism is dependent on the composition of the medium in which it is grown.

True

The primary mechanism by which DNA is damaged by ultraviolet radiation involves the formation of thymine dimers.

Trie

A microbial environment containing high nutrient concentrations is called an oligotrophic environment.

False

When the cell elongates, replicates its chromosome, and separates the chromosome into the two parts of the cell, and a septum forms at midcell, this process is called _______________.

Binary Fission

The limitation on microbial growth rate at high nutrient levels is

the saturation of transport proteins for nutrient uptake

The total number of viable microorganisms remains constant in stationary phase because

either there is a balance between cell division and death or there is a cessation of cell division even though the cells may remain metabolically active

A culture in a closed vessel to which no additional medium is added and from which no waste products are removed is called a __________ culture.

batch

Which of these methods can be used to determine the number of viable microorganisms in a sample?

Measuring colony forming units per ml

When a microorganism is placed in a(n) __________ solution, water will enter into the cell and cause it to burst unless something is done to prevent this.

hypotonic

Organisms that grow near deep-sea volcanic vents are likely to be

thermophilic

Organisms that grow near deep-sea volcanic vents are likely to be

barophilic or barotolerant

Organisms that grow in the mud under relatively nonturbulent bodies of water are likely to be

anaerobes

Membranes of thermophilic bacteria are stabilized by phospholipids with

fatty acids that tend to be more saturated

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

all of the choices

At 4:00 p.m. a closed flask of sterile broth is inoculated with 10,000 cells. The lag phase lasts 1 hour. At 9:00 p.m. the culture enters stationary phase with a population of 65 million cells. At what time is the population half maximal?

8:40PM

At 4:00 p.m. a closed flask of sterile broth is inoculated with 10,000 cells. The lag phase lasts 1 hour. At 9:00 p.m. the log phase culture has a population of 65 million cells. The mean generation time is approximately

20 minutes

The trace amounts of micronutrients needed by microorganisms are usually supplied as inadvertent contaminants in water and regular media components.

True

Zinc (Zn) is considered a macronutrient.

False

Copper (Cu) is considered a micronutrient.

True

Which of the following is not a major class of growth factors?

nucleic acids

__________ membranes allow some molecules to pass but not others.

Selectively permeable

Bacteria that can utilize methane, methanol, carbon monoxide, formic acid, and a few related one-carbon molecules as their principal source of carbon are called ____________.

methylotrophic

__________ membranes allow some molecules to pass but not others.

Selectively permeable

Which of the following is not considered a macronutrient?

cobalt (Co)

Which of the following is not considered a micronutrient?

magnesium (Mg)

Which of the following features is most likely to be associated with a lithotroph?

oxidization of an inorganic substrate

Which of the following processes can be used to bring nutrients into a cell against a concentration gradient?

active transport

Agar is an excellent solidifying agent for microbiological media because

it is not degraded by most microorganisms and solid agar remains solid until the temperature is raised to 90°C, and liquid agar remains liquid if the temperature is lowered to 45°C are correct.

A growth medium that favors the growth of some microorganisms but inhibits the growth of other microorganisms is a __________ medium.

selective

A growth medium that distinguishes among different groups of bacteria on the basis of their biological characteristics is called a __________ medium.

differential

Mannitol salt agar (MSA) only allows the growth of halophiles (salt-loving microbes); nonhalophiles will not grow. Among the halophiles, mannitol fermenters will produce acid that turns the pH indicator yellow; mannitol nonfermenters leave the medium red. Onto MSA you inoculate a halophilic mannitol fermenter and a halophilic mannitol nonfermenter. In this case, the medium is acting as (a) __________ medium(s).

differential

Mannitol salt agar (MSA) only allows the growth of halophiles (salt-loving microbes). Among the halophiles, mannitol fermenters release acid that turns the pH indicator yellow; mannitol nonfermenters leave the medium red. Onto MSA you inoculate a halophilic mannitol nonfermenter and a nonhalophilic mannitol nonfermenter. Here the medium acts as a __________ medium.

selective

Mannitol salt agar (MSA) only allows the growth of halophiles (salt-loving microbes). Among the halophiles, mannitol fermenters release acid that turns the pH indicator yellow; mannitol nonfermenters leave the medium red. Onto MSA you inoculate a halophilic mannitol fermenter, a nonhalophilic mannitol fermenter, and a halophilic mannitol nonfermenter. Thus, the medium is acting as a __________ medium.

selective and differential

You would like to culture a bacterium that is growing in the lung of a human patient with pneumonia. Which media would be of most use in culturing this organism?

complex medium supplemented with whole blood

All fastidious microorganisms require which of the following for growth?

extra nutrients (such as whole blood)

Which of the following can be used to isolate pure cultures of bacteria from mixtures?

all of the choices

Sulfur can be obtained from inorganic sources only.

False

Nitrogen can be obtained from either organic or inorganic sources.

True

Permease proteins that aid in the transport of nutrients resemble enzymes in their specificity for the substance to be transported. Each carrier is selective and will transport only a closely related set of substances.

True

The size and shape of a colony is not useful for identification of a microorganism because most microorganisms produce colonies that are indistinguishable from one another.

False

Serial dilutions can be used to estimate the total number of bacterial cells in a solution, including living and dead cells.

False

A branched network of hyphae formed by the Actinomycetes is called a __________.

mycelium

Actinomycetes form long filaments called ___________.

hyphae

Molecules or regions of molecules that readily interact with water are said to be __________, whereas molecules or regions of molecules that are insoluble in water or do not readily interact with water are said to be hydrophobic.

hydrophilic

A(n) __________ layer is a layer of protein or glycoprotein that exhibits a pattern resembling floor tiles.

S

The most widely accepted current model for membrane structures is called the __________ model.

fluid mosaic

_______ is a peptidoglycan-like molecule found in the cell walls of some archaea.

Pseudomurein

Intracellular granules of organic or inorganic material that are stockpiled by bacteria for future use are called __________.

inclusions

Bacteria have a region of the cytoplasm known as the __________, which is not bounded by a membrane but contains the chromosome.

nucleoid

Small circular DNA molecules capable of replicating and containing genes that are useful but not necessary to the bacterium are called __________.

plasmids

Some species of aquatic bacteria use inclusion bodies known as ________ to orient themselves in Earth's magnetic field.

magnetosomes

_______ are the site of protein synthesis in the cell.

Ribosomes

Bacterial flagella are composed of three parts: the ______ body, which is embedded in the cell, the hook, and the _______, which is the longest part of the flagellum.

basal, filament

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

coccobacilli

Bacterial cells that are variable in shape are called

pleomorphic

Square planar arrangement of cells that forms when round bacteria remain attached to each other during reproduction are called

tetrads

Flexible bacteria with a helical shape are called

spirochetes

Rigid bacteria with a helical cell shape are called

spirilla

The term used to describe bacteria that are shaped like curved rods is

vibrio

The term used to describe bacteria that are rod shaped is

bacillus

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

coccus

The lipopolysaccharide (LPS) that is found in the outer membrane of gram-negative bacteria is also known as

endotoxin

Proteins that are loosely associated with the cytoplasmic membrane are called __________ proteins.

peripheral

Proteins that are embedded within the cytoplasmic membrane and not easily extracted are called __________ proteins.

integral

Lipids with polar and nonpolar ends are said to be

amphipathic

Bacterial and archaeal ribosomes are known as _____ ribosomes, based on their sedimentation coefficient.

70S

Twitching or gliding motility involves

both type IV pili and movement of slime can be involved in twitching or gliding motility.

Sortase is a protein enzyme of bacteria that

catalyzes covalent attachment of some surface proteins to peptidoglycan.

Invisible living creatures were thought to exist and cause disease long before they were ever observed.

True

Agar is used as a solidifying agent for microbiological media because it is not readily digested by most microorganisms.

True

The usefulness of agar in solidifying microbiological growth media is limited because it does not remain solid at temperatures about 28oC.

False

Some microorganisms are useful in bioremediation processes that reduce the effects of pollution.

True

Light rays are refracted (bent) when they cross the interface between materials with different refractive indices.

True

A substage condenser is used to focus light onto the specimen, which increases the resolution of a light microscope.

True

Confocal microscopes, in combination with specialized computer software, can be used to create three-dimensional images of cell structures.

True

Resolution decreases when the wavelength of the illuminating light decreases.

False

Immersion oil is used to prevent a specimen from drying out.

False

Immersion oil increases the amount of light passing through a specimen and entering the objective lens.

True

Gram staining divides bacterial species into roughly two equal groups.

True

Negative staining facilitates the visualization of bacterial capsules which are intensely stained by the procedure.

False

Negative staining with India ink can be used to reveal the presence of capsules that surround bacterial cells.

True

Mordants increase the binding between a stain and specimen.

True

In order to stain flagella so that they may be readily observed by light microscopy, it is usually necessary to increase their thickness.

True

It was possible to view viruses only after the invention of the electron microscope because they are too small to be seen with a light microscope.

True

During the assembly of the flagellar filament, the flagellin protein monomers assemble at the cell proximal base of the flagellum.

False

Although a particular microbial species usually can be defined as a particular nutritional type, some show great metabolic flexibility and alter their metabolic patterns in response to environmental changes.

True

Phosphorus can be obtained from organic sources only.

False

Organisms usually have only a single transport system for any nutrient.

False

Different transport systems for the same nutrient that are part of the same organism are usually regulated in different ways.

True

The extreme insolubility of ferric iron leaves little free iron available for transport into bacterial cells.

True

Blood agar is both a differential and enriched medium.

True

All bacterial and archaeal cells are diploid.

False

During the lag phase of microbial growth, the cells are metabolically inactive.

False

One of the major advantages of a continuous culture system is that the cells can be maintained in the exponential growth phase for extended periods of time.

True

Obligate anaerobes are usually poisoned by molecular oxygen but may grow in aerobic habitats if associated with facultative anaerobes that use up all available oxygen.

True

DNA of thermophiles is stabilized by binding of special nucleoid-associated proteins.

True

Membranes of some thermophilic Archaea are stabilized by ether linked phospholipids.

True

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

Eukaryotes

Cells with a relatively simple cell morphology that do not have a true membrane-delimited nucleus are called

Prokaryotes

Definition of life includes all of the following except

cells lack response to external environment

Proteins function in modern cells as

catalysts;structural elements

RNA serves to convert the information stored in DNA to ________.

protein

Who of the following provided the evidence needed to discredit the concept of spontaneous generation?

Pasteur

The concept that living organisms arise from nonliving material is called

Spontaneous generation

Studies by Emil von Behring and Shibasaburo Kitasato demonstrated that inactivated toxins can induce the synthesis of antitoxins in the blood of rabbits. These antitoxins (antibodies) are the basis of

Humoral immunity

Old cultures of bacteria that have lost their ability to cause disease are said to be

Attenuated

Which of these microscopes can be used to create high-resolution three-dimensional images of cells?

Confocal

A 30× objective and a 20× ocular produce a total magnification of

600x

A 45× objective and a 10× ocular produce a total magnification of

450x

A microscope that exposes specimens to ultraviolet, violet, or blue light and forms an image with the light emitted at a different wavelength is called a __________ microscope.

Fluorescence

Immersion oil can be used to increase the resolution achieved with some microscope lenses because it increases the __________ between the specimen and the objective lens.

Neither optical density nor refractive index

If the objective lenses of a microscope can be changed without losing focus on the specimen, they are said to be

Parfocal

An instrument that magnifies slight differences in the refractive index of cell structures is called a (n) __________ microscope.

Phase-contrast

The instrument that produces a bright image of the specimen against a dark background is called a (n) __________ microscope.

Dark-field

Acid-fast organisms such as Mycobacterium tuberculosis contain __________ constructed from mycolic acids in their cell walls.

lipids

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