Lab Exam – Microbiology – Flashcards

A colony is a ___1____ microbial growth on a solid medium that originated from a ______2______ and through cell division produced a multitude of identical daughter cells.

Useful colony characteristics for differentiation of bacterial species include    1    ,     2    ,     3    ,          4   ,     5    ,    6    . For example, Serratia marcescens luteus colonies are red, irregular in shape, and have a strong odor. Micrococcus colonies, on the other hand, are yellow, opaque, round, and dome-shaped.

When working with culture that may contain millions of cells, dilution on to a solid medium is essential for    1     the cell with enough space so that they grow into    2     colonies.

The streak plate method does not require any additional      1     for dilution and only requires

      2        for inoculation

The loop is flamed before entering a culture tube to ensure that         1         microbes are introduced in to the culture. The loop is flamed afterward so that           2          are introduced into the          3            .

Plates are inverted during incubation so that

         1      accumulate on the lid and drop on to the agar surface. This will cause the organisms 

        2         the dilution effect.

 Refrigeration is used to control spoilage microbes in food but psychrotrophs, such as         1       , are still capable of growth at these temperatures.

Most human pathogens grow best at      1      , which is     2      temperature. 

Temperature affects metabolism by influencing

      1       ,        2      , and      3     .

UV radiation causes the formation of     1       in DNA that result in     2     errors during reproduction. These errors cause        3       which ultimately lead to cell death.

Endospores are     1      cells and are not subject to the same effects as      2      vegetative cells.

UV radiation is most germicidal at        1         because that is the wavelength at which DNA

       2          UV light.

UV radiation can cause damage to     1     and can cause      2     . It also can cause        3      . In this experiment, goggles are worn to protect the eyes and one should avoid looking directly at the UV light source. In everyday life, wearing long clothing, a hat, and/or sunscreen will protect against the damaging UV rays of the sun.

 A  B. megaterium culture in stationary phase will contain more     1     as nutrients become limited and therefore would demonstrate the best survival following exposure to UV radiation.

For antisepsis of skin, alcohol has advantages over soap because it is a     1     agent, does not require water, and does not need to be wiped off because it readily    2   .

Antiseptics, such as alcohol or iodine, are used on 

         1          . Disinfectants, such as bleach, are used on         2           . Most antiseptics (e.g. alcohol, iodine, peroxide) can be used as disinfectants, but most disinfectants are

  3   recommended for use     4    (e.g. bleach, 

Lysol, ammonia).

The size of the zone of inhibition is influenced by the        1         of the agent and its         2         in the agar.

Gram-negative bacteria have        1         that may limit penetration of chemicals that harm

         2         targets. This makes them more

        3       to being killed by those chemicals than the gram positive bacteria.

The advantages are        1      ,      2       ,

       3        ,       4      ,        5      ,       6      ,

      7      ,        8      ,       9        . The disadvantages are having to confirm questionable test results and multitest systems are designed for a particular medically important group of pathogens and are                   10                    .

The          1          is done to confirm that the unknown is a member of the family Enterobacteriaceae. These organisms test

         2           .

All enterobacteria ferment glucose and produce

                1                  .

A “0” as the first number of the code indicates

       1       , i.e. not a glucose fermentor.  Gram-negative bacilli that do not      2       include Pseudomonas, Plesiomonas, Vibrio, Achromobacter, Moraxella, Pasteurella, Aeromonas, Alcaligenes, and Bordatella. These bacteria are likely oxidase      3      and should be identified with the       4       Tube II system (Exercsie 47).

 The VP test is utilized when the 5-digit code provides        1         and the interpretation guide indicates that the VP test can

          2        .

 Contaminated or mixed cultures as well as

         1          may provide “nonsense” profiles that cannot be found.  

       1         in grape juice are fermented.  Fermentation produces       2      and       3      .

Expansion of the balloon demonstrates production of       1       gas. The rubber stopper would trap gas, causing the formation of gas bubbles in 

the wine, and yield         2          or        3       .

Acetobacter contamination would result in      1       production, which would impart a sour taste to the wine.  This change can be measured as a lowered

  2   of the wine. This process is performed in the production of       3       by some manufacturers.

Hydrogen sulfide production would impartan

        1         and           2        .

Starches from the flour in bread dough are used for fermentation.      1     and      2     are produced.      3       causes the bread dough to rise before baking and      4      evaporates during baking. Lactobacillus sanfrancisco bacteria ferment sugars in the bread dough to produce       5      , which is responsible for the taste of sour dough bread.

Fermentation contributes to food preservation by creating       1      and       2       environment that inhibits the growth of many

       3       .