SERIES MICROBIOLOGY LAB - EXAM 2 COMPLETE QUESTIONS AND CORRECT ANSWERS | GRADED AND THE LATEST SERIES

2025-2026 SERIES
MICROBIOLOGY LAB - EXAM 2 COMPLETE
QUESTIONS AND CORRECT ANSWERS | GRADED
AND THE LATEST SERIES
medium


Ans: a mixture of nutritional substances on or in which microorganisms grow


Question: autotroph


Ans: nutritionally deficient mutants that have lost the ability to synthesize a
particular enzyme


many microorganisms in this group:
- can carry out photosynthesis
- usually do not cause disease
- synthesize organic compounds to obtain energy


Question: heterotroph


Ans: an organism that uses compounds to produce biomolecules


Question: autoclave


Ans: an instrument for sterilization by means of moist heat under pressure


Question: Autoclaving combines ____ and ____ to destroy high resistant

bacteria.

, 2025-2026 SERIES
Ans: high temp and high pressure


Question: What are six basic nutritional requirements of every living thing?


Ans: Water, carbon, nitrogen, metallic elements, energy and growth factors such
as vitamins


Question: general purpose media


Ans: Designed to grow a broad spectrum of microbes that do not have special
growth requirements


Question: enriched media


Ans: medium that contains special additives that could promote certain metabolic
activities. (ex. trypticase soy agar, blood agar, yeast extract broth)
- especially used for fastidious bacteria


Question: selective media


Ans: is a nutrient that inhibits the growth of a certain type of microorganisms (ex.
Gram + bacteria) while permitting the growth of a different type (in this example,
Gram - )


Question: differential media


Ans: medium which will differentiate between bacteria based on how they
change the medium or their appearance on the medium


Question: EMB and HE are both ____ and ____.

, 2025-2026 SERIES
Ans: selective and differential


Question: EMB and HE are selective for ____ and differential for ____.


Ans: selective for gram-negative bacteria and differential for lactose fermenters.


Question: What do lactose fermenters and nonfermenters look like on each

media?


Ans: - Organisms which quickly ferment lactose will give dark-green to black
colonies on this medium; these colonies have a metallic sheen (Ecoli)


- Organisms that are slow fermenters of lactose will give pink to maroon colonies on
this medium. Those organisms that cannot ferment lactose at all give white
(colorless) colonies on EMB agar (since nonfermenters of lactose are often high
pathogenic, this is a useful way to identify potential pathogens)


Question: What is Shigella associated with?


Ans: a genus associated with bacillary dysentery


Question: HE and EMB are useful for distinguishing between _____.


Ans: Enterobacteriaceae


Question: What are Enterobacteriaceae?


Ans: a group of short, Gram-negative, facultative anaerobic rods that are found
in the intestinal tract of various mammals, including humans


Question: PEA and MS agar are _____ for ____.