Micro Lab 5 Questions

Match the phase of microbial growth in the left-hand column to its description in the dropdown menu.

lag phase-little growth; bacteria are acclimating to new growth conditions

log phase-exponential increase in population

stationary phase-microbial death balance production of new cells

death phase-popularion decrease at a logarithmic rate

Match the definition on the right side to the term it describes from the drop down menu.

heat loving; optimum growth 40 to 75 degrees C-thermophile

salt loving; growth in high concentrations of salt-halophile

moderate temperature loving; optimum growth 10 to 50 decrees C-mesophile

optimum growth 0 to 30 degree C-psychrotroph

alkaline loving growth in alkaline conditions-alkaliphile

excessive heat loving; optimum growth from 65 to 120 degrees C-extreme thermophile

acid loving; growth in acidic conditions;-acidophile

cold living; optimum growth in -20 to 10 degrees C-psychrophile

What are the nutrient requirements for an organism classified as a photoautotroph?

sun and CO2

Most extremophilic organisms belong to the domain ______.

archaea

____ are moderate temperature-loving organisms that optimally grow at 25-40 degrees C.

mesophiles

True or False? Most human pathogenic bacteria are thermophiles

False

Many food spoilage bacteria are characterized by temperature as ______.

psychotrophs

In what type of conditions would you expect to find a halophilic acidophile?

high salt and low pH conditions

True or False? Agar is a seaweed derivative that is added to culture media to solidify it at room temperature.

True

A certain species of bacteria grows best on 25% glucose, 5% NaCl, and 0.2% magnesium sulfate agar plates. From this description, identify this general type of growth media.

Chemically defined

A certain species of bacteria grows the best on 5% peptone, 5% beef heart extract, and 8% sodium chlorida. From this description, identify this general type of growth media.

complex

True of False? Turbidity in liquid culture media indicates there is bacterial growth.

True

The red arrows are pointing to _________________.

a single bacterial colony

True or False? A single colony of bacteria contain genetically diverse bacteria bacteria.

false

The image shows the results of three different bacterial species grown on MacConkey media. What sugar is used in the formulation of MacConkey media?

lactose

This image shows the results of three different bacterial species grown on MacConkey media. Which bacterial species, if any, are likely Gram-negative?

A, B, and C

This image shows the results of three different bacterial species grown on MacConkey media. Which bacterial species, if any, ferment lactose?

B and C only

This image shows the results of three different bacterial species grown on MacConkey media. Escherichia coli is a very stron lactose fermenter. Which letter likely indicates E. coli growth?

C

This image shows the results of three different bacterial species grown on EMB media. What sugar is used in the formulation of EMB media?

Lactose

This image shows the results of three different bacterial species grown on EMB media. Escherichia coli is a very strong lactose fermenter. Which letter likely indicates E. coli growth?

C

This image shows the results of three different bacterial species grown on MacConkey media. Which bacterial species, if any, are Gram-positive?

none of the bacterial species are Gram-positive

The results in this image represent 4 different bacterial species inoculated onto an MSA plate. Which organism(s) is(are) halophilic and ferment mannitol?

A and C

The results in this image represent two different bacterial species inoculated on an MSA plate. What sugar is used in the formulation of MSA media?

mannitol

The results in this image represent two different bacterial species inoculated on an MSA plate. Which, if any, organism(s) ferment mannitol?

B only

The results in this image represents two bacterial species inoculated on an MSA plate. Which, if any, organism(s) are halophilic?

both A and B

Streptococcus pneumoniae exhibits a greenish appearance when grown on sheep's blood agar. What type of hemolytic pattern does this indicate?

alpha

Streptococcus pyogenes, the etiological agent of strep throat, scarlet fever and rheumatic fever, exhibits complete clearing of RBCs when grown on sheep's blood agar. What type of hemolytic pattern does this indicate?

beta

Escherichia coli yields whitish colonies when grown on sheep's blood agar. What type of hemolytic pattern does this indicate?

gamma

What is the rational of having high salt content in the diagnostic media, MSA?

to select for halophiles and/or facultative halophiles

The selective & differential media called MAC contains a chamical called neutral red that will detect a change in pH if the sugar in the media is metabolized by the growing organism. What is the general term for the chemical added to media that detect changes in pH?

indicator

Sheep's blood agar differentiates between bacteria that produce a toxin called _______, which is indicated by the partial or complete destruction of red blood cells contained in the media.

hemolysin

When a sheep's blood agar plate is streaked with bacteria, such as Streptococcus pyogenes, beta hemolysis occurs. What does beta-hemolysis indicate about the pathogenicity of S. pyogenes?

it is likely to be pathogenic