Chapter 4 Micro

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Imagine you are a microbiologist trying to isolate new species of prokaryotes. You collect numerous samples and return to your lab, where you proceed to encourage any prokaryotes present to grow. Disappointingly, you are not successful. Which is the LEAST likely explanation for this outcome?

Compounds or conditions that you provided inhibited their growth.

The prokaryotes depended on a close association with others in order to grow.

You did not manage to provide them with all the major elements, trace elements, and growth factors necessary to support their growth.

Your atmospheric conditions did not sufficiently match those found in their environment.

There were no prokaryotes present where you sampled.

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Imagine you are a microbiologist trying to isolate new species of prokaryotes. You collect numerous samples and return to your lab, where you proceed to encourage any prokaryotes present to grow. Disappointingly, you are not successful. Which is the LEAST likely explanation for this outcome?

Compounds or conditions that you provided inhibited their growth.

The prokaryotes depended on a close association with others in order to grow.

You did not manage to provide them with all the major elements, trace elements, and growth factors necessary to support their growth.

Your atmospheric conditions did not sufficiently match those found in their environment.

There were no prokaryotes present where you sampled.

There were no prokaryotes present where you sampled.

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Bacteria and archaea typically divide by a process known as .___________ ________

binary fission

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Bacteria growing in a natural environment experience ______.

Multiple choice question.

dynamic and complex conditions

conditions similar to that of the laboratory

dynamic and complex conditions

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What term is used to describe a group of microbes co-existing in polymer-encased communities?

Multiple choice question.

Biolayer

Biofilm

Slime layer

Slime film

Biofilm

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Which of the following does not describe interactions of mixed microbial communities?

Multiple choice question.

Conditions in mixed microbial associations are readily reproduced in the laboratory.

Microbial cells can consume O2, creating microenvironments in which anaerobes can thrive.

Microbes can compete for nutrients.

Some microbes can synthesize toxic compounds to inhibit competitors.

Microbes can interact cooperatively and even foster the growth of species that otherwise could not survive.

Conditions in mixed microbial associations are readily reproduced in the laboratory.

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Some species of microorganisms can be found in environments where no unprotected human could survive.

True false question.

True

False

True

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Multiple Choice Question

Which of the following is most likely to be a pure culture?

Multiple choice question.

A bacterial lawn of growth covering an agar plate.

A Petri dish covered with bacteria following inoculation from a single patient.

A broth culture growing in a flask.

A single colony growing on a streak plate.

A single colony growing on a streak plate.

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This figure shows a bacterium dividing. The mechanism is called


binary fission

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A colony is a distinct mass of microorganisms which develop from a single cell growing on a solid medium.

True false question.

True

False

True

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Which environment is more dynamic and complex?

Multiple choice question.

A laboratory environment

Soil and its surroundings

Soil and its surroundings


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Culture media are usually solidified by the addition of a polysaccharide extracted from seaweed. This polysaccharide is known as

agar

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Many bacterial communities secrete polysaccharides and other hydrophilic polymers. This mesh-like accumulation can help protect the bacteria growing within from antibiotics or disinfectants. These communities are called

biofilms

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When bacteria or archaea are grown on agar plates or in tubes or flasks of broth, these closed systems are a _______culture. By contrast, cells can also be grown in an open system, or a continuous culture.

batch

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Consider interactions of mixed microbial communities. Match the descriptions in the left column with those that best correlate with them in the right column.

Instructions

Difficult to reproduce in the laboratory

Simpler to reproduce in the laboratory

Inhibit competitors

Nutrients for another microbe

Creation of low O2 microenvironment

  1. Production of metabolic wastes by one microbe

    Conditions in close microbial associations

    Consumption of O2 by aerobic growth

    Synthesis of toxic compounds

    Pure cultures

Difficult to reproduce in the laboratory & Conditions in close microbial associations

Simpler to reproduce in the laboratory & Pure cultures

Inhibit competitors & Synthesis of toxic compounds

Nutrients for another microbe & Production of metabolic wastes by one microbe

Creation of low O2 microenvironment& Consumption of O2 by aerobic growth


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A(n)______ culture contains only ONE species of microorganisms descended from a single cell.

pure

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A graphical representation of a changing population size over time is called which of the following?

Multiple choice question.

growth curve

histogram

generation time

growth curve

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An isolated ______ is a distinct mass of microorganisms appearing on a solid medium, arising from the multiplication of a single cell.

colony

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______ phase describes the initial phase after bacterial cells are placed into a new environment and are gearing up for cell division, but their numbers have not yet increased.

lag

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The polysaccharide found in marine algae that is commonly used to solidify culture media is called ______.

agar

peptone

starch

gelatin

agar

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In which phase of the growth curve is the generation time measured?

Multiple choice question.

Death

Lag

Log

Stationary

Log

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A batch culture has which of the following characteristics?

Multiple select question.

It is a closed system.

It is an open system.

Nutrients are not renewed.

It typically involves growth of bacteria or archaea either on agar plates or in tubes or flasks of broths.

Wastes are not removed.

Cells are maintained in a state of continuous growth.

It is a closed system.

Nutrients are not renewed.

It typically involves growth of bacteria or archaea either on agar plates or in tubes or flasks of broths.

Wastes are not removed.

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During which phase of growth does the number of new cells balance the number of declining cells?

Multiple choice question.

Stationary phase

Log phase

Death phase

Lag phase

Stationary phase

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Which of the following does not describe interactions of mixed microbial communities?

Multiple choice question.

Conditions in mixed microbial associations are readily reproduced in the laboratory.

Microbes can interact cooperatively and even foster the growth of species that otherwise could not survive.

Microbes can compete for nutrients.

Some microbes can synthesize toxic compounds to inhibit competitors.

Microbial cells can consume O2, creating microenvironments in which anaerobes can thrive.

Conditions in mixed microbial associations are readily reproduced in the laboratory.

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In a growth curve, cell numbers increase exponentially during the log phase and decrease exponentially during the death phase.

True false question.

True

False

True

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The characteristic pattern that shows the changes in size of a bacterial population over time in a broth culture is called a bacterial . _________ __________

growth curve

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In what ways is microbial growth in a colony the same as growth in a liquid?

Multiple select question.

Cells in either situation are all in the same phase of growth at the same time.

Cells in both situations experience the same levels of nutrients.

In both cases, cells compete with one another for available nutrients.

Both involve a lag phase followed by exponential growth.

In both cases, cells compete with one another for available nutrients.

Both involve a lag phase followed by exponential growth.

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Which of the following characterizes the lag phase of a normal bacterial growth curve?

Multiple choice question.

Cells are undergoing logarithmic cell division.

Depletion of nutrients and buildup of waste. While some cells multiply, others die, and the overall population remains relatively constant.

Cells are declining exponentially.

Cells are synthesizing enzymes needed for growth but not increasing in number.

Cells are synthesizing enzymes needed for growth but not increasing in number.


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Which device is used to keep cells in a state of constant growth?

Multiple choice question.

Chemostat

Flow cytometer

Spectrophotometer

Thermocycler

NMR

Chemostat

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The log (logarithmic) phase of a normal growth curve is also referred to as the______ phase.

exponential

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Some microorganisms live in harsh environments that kill most other organisms. The term used to describe an organism with this characteristic is .______

extremophiles

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The ______phase of the bacterial growth curve is when there are an equal number of cells dividing as there are dying.

stationary

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Which of the following describes the optimum temperature of a psychrophile relative to a thermophile?

Multiple choice question.

It is lower than a thermophile.

It is higher than a thermophile.

It is the same as a thermophile.

It is lower than a thermophile.


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In which phase of the growth curve is the number of viable cells decreasing?

Multiple choice question.

log

lag

stationary

death

death


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Match the term on the left with the description of the optimum temperature environment.

Instructions

psychrophile

cold Arctic regions


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Match the term on the left with the description of the optimum temperature environment

.

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Match the term on the left with the description of the optimum temperature environment.

psychrotroph

refrigeration

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Match the term on the left with the description of the optimum temperature environment.

mesophile

human body

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Match the term on the left with the description of the optimum temperature environment.

thermophile

compost heap

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Why are cells growing in a colony on solid media likely to be in many more different phases of growth than cells growing in liquid culture?

Multiple select question.

Cells grow much more quickly in liquid culture, so they are more likely to stay in the same phase.

Growth on solid media provides a greater abundance of nutrients, so cells are able to rapidly separate out into different phases of growth.

Unlike cells on the edge of a colony, those in the center of a colony face depleted levels of nutrients and O2, yielding different phases of growth.

Cells in liquid culture experience a relatively uniform environment, so they are much more likely to be in the same phase of growth.

Unlike cells on the edge of a colony, those in the center of a colony face depleted levels of nutrients and O2, yielding different phases of growth.

Cells in liquid culture experience a relatively uniform environment, so they are much more likely to be in the same phase of growth

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A continuous culture system that adds nutrients and removes waste in order to maintain a constant growth rate and cell density is called a _____

chemostat/ bioreactor

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Which term describes a microorganism that has an optimum temperature between -50C and 150C?

Multiple choice question.

Psychrophile

Mesophile

Thermophile

Psychrotroph

Psychrophile

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Consider the following environmental factors. Which have the most impact on microbial growth?

Multiple select question.

wind speed

pH

atmosphere

water availability

odor

temperature

pH

atmosphere

water availability

temperature

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A species grows most rapidly at its____ growth temperature.

optimum

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Which term describes a microorganism that has an optimal temperature between 15āˆ˜C and 30āˆ˜C, but grows well on refrigerated foods?

Multiple choice question.

Mesophile

Thermophile

Psychrotroph

Psychrotroph

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he five groups used to categorize microorganisms with respect to growth temperature (psychrophile, psychrotroph, mesophile, thermophile, and hyperthermophile) ______.

Multiple choice question.

represent the entire range at which the organisms in the groups can grow.

are based on optimum growth temperatures.

are precise with respect to the dividing lines between each group.

are based on optimum growth temperatures.


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Human pathogens, adapted to growth in the human body, are ______.

Multiple choice question.

psychrophiles

hyperthermophiles

mesophiles

psychrotrophs

thermophiles

mesophiles

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In what ways is microbial growth in a colony the same as growth in a liquid?

Multiple select question.

In both cases, cells compete with one another for available nutrients.

Cells in both situations experience the same levels of nutrients.

Both involve a lag phase followed by exponential growth.

Cells in either situation are all in the same phase of growth at the same time.

In both cases, cells compete with one another for available nutrients.

Both involve a lag phase followed by exponential growth.

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An environment with little or no O2 present is called a(n)________ environment

anaerobic

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If you wanted to study psychrophilic microorganisms, you would most likely find them ______.

Multiple choice question.

in water from a hot tub

growing on your skin

in lakes fed by glaciers

in lakes fed by glaciers

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Which of the following describes a microbe that must have O2 to survive?

Multiple choice question.

Semi aerobe

Facultative aerobe

Passive aerobe

Obligate aerobe

Obligate aerobe


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Some microorganisms live in harsh environments that kill most other organisms. The term used to describe an organism with this characteristic is .________

extremophile

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From which body site could a facultative anaerobe be isolated?

Multiple choice question.

Surface of skin

Any of these locations

Intestine

Deep wound

Any of these locations


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Multiple Choice Question

A ______ is most likely to be implicated in spoilage of refrigerated foods.

Multiple choice question.

mesophile

thermophile

psychrotroph

hyperthermophile

psychrotroph

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Bacteria that cannot multiply if O2 is present, and are often killed by even brief exposure to air, are termed _______ ________

obligate anaerobes

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E. coli and most other common bacteria are ______.

Multiple choice question.

mesophiles

thermophiles

psychrotrophs

hyperthermophiles

psychrophiles

mesophiles

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A(n________) is an aerobe that requires O2 at a concentration less than that in the atmosphere.

microaerophile

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If O2 is present in an environment, it is said to be _______.

Multiple choice question.

aerobic

aerotactic

aerophilic

aerobic

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Which of the following organisms does not use O2 at all for growth?

Multiple choice question.

Aerotolerant anaerobe

Facultative anaerobe

Microaerophile

Aerotolerant anaerobe


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A(n)______ aerobe, or strictly aerobic organism, requires O2 for survival.

obligate

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Regardless of the pH of the external environment, microbial cells maintain a constant internal pH, typically near neutral. For example, prokaryotes that grow in alkaline conditions bring ______ into the cell.

protons

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Which of the following correctly describe facultative anaerobes?

Multiple select question.

Their growth is faster when O2 is available.

They can only grow in the absence of O2.

They can grow without O2.

They can grow in the presence of O2 but do not use it to harvest en

Their growth is faster when O2 is available.

They can grow without O2.

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If you inoculated a test tube of cooled liquid agar with an obligate anaerobe and incubated it, where would you expect to find growth?

Multiple choice question.

Only at the bottom of the tube.

Throughout the tube.

Only at the top of the tube.

Only at the bottom of the tube.


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Which answer best explains the events in the figure leading to plasmolysis?

Multiple choice question.

There is a greater concentration of water outside the cell, so water flows from inside to outside the cell.

The solute concentration inside the cell is greater than outside the cell, causing water to diffuse out of the cell via osmosis.

The solute concentration of the medium is greater than that in the cell, causing water to diffuse out of the cell due to osmosis.

There is more solvent outside the cell than inside, so water exits the cell.


The solute concentration of the medium is greater than that in the cell, causing water to diffuse out of the cell due to osmosis.


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A microbe that requires small amounts of O2 (2-10%) for aerobic respiration but is inhibited by higher concentrations is called a(n) ______.

Multiple choice question.

microaerophile

aerotolerant anaerobe

obligate aerobe

facultative anaerobe

microaerophile

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Carbon, oxygen, hydrogen, nitrogen, sulfur, and phosphorus, are examples of chemical substances called ________ ________, which are the essential components of the cell's macromolecules.

major elements

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A microbe that doesn't use O2 but can grow in environments containing O2 is described as a(n) _______anaerobe.

aerotolerant

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Microbial cells must maintain a near-neutral internal pH. Because of this, bacteria that grow in acidic environments have mechanisms to ______.

Multiple choice question.

pump out OH- that enter the cell

bring OH- into the cell

bring H+ into the cell

pump out H+ that enter the cell

pump out H+ that enter the cell


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An organism that must consume organic matter is called a(n) .______

heterotroph

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What term is used to describe organisms that use CO2 as a carbon source?

Multiple choice question.

Heterotrophs

Saprotrophs

Autotrophs

Autotrophs

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If the solute concentration is higher outside the cell than inside the cell, water will diffuse out due to osmosis. This will result in

plasmolysis

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What term is used to describe chemical substances such as carbon or phosphorous, which are found in large quantities in cells?

Multiple choice question.

Macroelement

Megamolecule

Macromolecule

Macrocompound

Major element

Major element

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Animals could not survive without autotrophs because without them the world would run out of ______.

Multiple choice question.

organic nitrogen

organic carbon

inorganic nitrogen

inorganic carbon

organic carbon

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Which of the following organisms does not use O2 at all for growth?

Multiple choice question.

Microaerophile

Facultative anaerobe

Aerotolerant anaerobe

Aerotolerant anaerobe


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Which of the following contain nitrogen?

Multiple select question.

Carbohydrates

Proteins

RNA

DNA

Fats

Proteins

RNA

DNA

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Which type of organism requires organic compounds for its carbon and energy needs?

Multiple choice question.

Autotroph

Heterotroph

Phototroph

Heterotroph

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Nitrogen fixation is the process by which some prokaryotes convert atmospheric nitrogen into _______and then incorporating that into cellular material.

ammonia or NH3

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A(n)_______ requires only carbon dioxide as a sole carbon source.

autotroph

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What term is used to describe essential organic compounds, such as a vitamin or amino acid, that must be provided in the diet?

Multiple choice question.

Inhibitory regulators

Trace element

Virulence factors

Growth factors

Growth factors


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Autotrophs play a crucial role in the cycling of carbon in the environment by converting inorganic carbon to an organic form. This process is called carbon .______

fixation

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Unlike sugar, proteins provide which of the following elements?

Multiple choice question.

Hydrogen

Nitrogen

Oxygen

Carbon

Nitrogen

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Which term is used to describe organisms that can obtain energy directly from sunlight?

Multiple choice question.

Chemotrophs

Phototrophs

Saprotrophs

Phototrophs

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Some microorganisms can convert nitrogen gas (N2) to ammonia in a process called _______.

Multiple choice question.

denitrification

nitrogen fixation

nitrogen assimilation

nitrification

nitrogen fixation


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An autotrophic organism that uses light for energy and carbon dioxide as a carbon source is termed a _______

photoautotroph

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A______ factor is an organic compound, such as a vitamin or an amino acid, that a given microorganism cannot synthesize and therefore must be provided in the growth medium.

growth

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