Microbiology quiz questions unit 1

In a serial dilution, the final dilution factor performed was 1:100,000. After 48 hours incubation @ 37C there were 190 colonies counted on the plate. What was the concentration of bacteria in the original undiluted sample?

19,000,000 cfu/mL

Lysis of red blood cells occurs but the iron in the RBC is not consumed as a food source

Alpha hemolysis

This is the complete lysis of red blood cells on blood agar where all of the contents of the cells were consumed as a nutritional source

Beta hemolysis

Patient samples, after specimen collection, that were transported promptly but inaccurately labeled with be tested anyway.

False

Bacteria is growing on the agar but there is no change in the appearance or color of the blood agar and no lysis of red blood cells.

Gamma hemolysis

You observe an organism under the light microscope in the lab and have positively identified that it is multicellular and have determined that it belongs to the Domain Eukarya. You also observe no visible chloroplast and can clearly identify separate visible body regions. This organism must belong to___

Kingdom Amimalia

MacConkey Agar

MAC is most commonly used for the selective isolation of (a.)________ and differentiate them based on (b.)________ resulting in a color change. a. gram negative species b. lactose fermentation

Concerning the inoculation techniques discussed in this lab, one difference between the "spread plate method" and the "streak plate method of isolation" is______ and one similarity is ______?

One difference between the two techniques is that the "spread plate method" is used to evenly distribute the bacteria across the entire plate and a similarity is the end result should produce pure colonies in both methods

When performing a serial dilution, a student forgot to change the pipette and used the same pipette for every .5mL transfer of the solution from tube to tube. Would these results be accurate and what would you predict the outcome would be?

These results would be inaccurate because the extra culture on the inside and outside of the pipette would increase the concentration of the next tube beyond the factored amount.

After performing a serial dilution a student counted 9 colonies on the 1:100,000 plate and 21 colonies on the 1:10,000 plate, Was this an accurate serial dilution? Why or why not?

This was not an accurate serial dilution because the number of colonies counted on the 1:100,000 plate was not within the target window and the difference in the count between the two plates was not close to a factor of 10.

According to taxonomy of living organisms yeast and mold both belong to the the Kingdom Fungi.

True

The appearnce of a greenish color with bacterial growth on blood agar

alpha hemolysis

a fundamental technique important in the laboratory and used by microbiologists for a variety of procedures such as transferring cultures, inoculating media and isolation of pure cultures is known as?

aseptic technique

In this type of hemolysis a clear zone is left behind in the agar

beta hemolysis

This is due to the lysis of red blood cells, in blood agar, and the complete absorbance of the nutrients from the red blood agar, leaving behind a clear zone on the agar.

beta hemolysis

Differential media is a type of specialty media which?

contain specific dyes that cause a color change as different bacteria grow and produce waste products.

Blood agar

differential

Which Gram is more resistant to antibiotics?

gram negative

Parafocal

image should remain in focus when objectives are changed

parcentric

image stays in center of field as one moves from one objective to another

You observe an organism under the light microscope in the lab and have positively identified that it is single celled. It has no internal membrane bound organelles. It clearly has several hairlike structures protruding from one end of an oblong cell shape. Your instructor tells you these are flagella. This organism belongs to____

kingdom bacteria

An agar that contains a dye and/or indicator and a growth inhibitor as part of its ingredients can be best be described as.

selective and differential

MAC

selective and differential

List 4 protocols that must be followed for the collection of a biological specimen in order to obtain a timely and valid laboratory result

-it must be collected in the presence of the patient and labeled with 2 identifiers(such as patient name and number). -collected samples must be transported to the laboratory as soon as possible. -Samples must be collected using proper collection techniques -it must be collected in the proper container

aseptic technique is a fundamental and important laboratory skill in the field of microbiology. Choose some examples of how or why aseptic technique would be used in a laboratory.

-proper aseptic technique prevents contamination of cultures from foreign bacteria inherent in the environment -using proper aseptic technique can greatly minimize or even eliminate the risk of contamination. -aseptic technique prevents microbes used in the laboratory from accidentally being released into the environment and/or infecting people working in the laboratory.

In the serial dilution procedure of this laboratory exercise the dilution was increased with each transfer to the next tube by a factor of_____?

10

A method used to dilute a substance in a stepwise manner into a solution with a constant dilution factor is known as?

Serial dilution