Study Objectives for Exam 2
Covering Microbial Growth (Chapters 4), Food Microbiology (Chapters 31 and
parts of Chapters 24 and 16), and Microbial Control (Chapter 5).
Use your lecture notes and the reading guides to help you focus on the most
important material covered in these chapters.
Chapter 4: Prokaryotic Growth
1. Understand what is meant by generation time, and binary fission. Do all organisms
have the same generation time? Be able to use the formula on p. 83 to calculate the
number of cells in a population after a given amount of time.
2. What is a biofilm? What are some medical applications/examples of biofilms? Are all
biofilms damaging?
3. What is the definition of a pure culture? What are some techniques used to determine
if a sample is pure? How are stock cultures maintained?
4. Explain how physical conditions such as temperature, pH, and oxygen can influence
bacterial growth.
5. What is the optimum temperature for growth of psychrophiles, psychrotrophs,
mesophiles, and thermophiles?
6. What are the basic chemical requirements for bacterial growth?
7. What is the difference between chemically defined media and complex media?
8. What are selective media? What are differential media? Know some examples of
each.
9. Know the definitions of the following terms: photoautotroph. photoheterotroph,
chemoautotroph, and chemoheterotroph
10. Be able to look at a recipe and determine what kind of microbe would grow on it, for
example, chemoheterotroph, photoautotroph, etc.
11. Be able to recognize a bacterial growth curve and identify the phases of growth.
Which growth phase is best used for experimentation and why? When are primary
metabolites produced? Secondary metabolites?
12. Describe the following methods to determine the number of bacteria
-Direct cell counts
-Viable Cell Counts
-Measuring Biomass
-Detecting Cell Products
Which methods measure living cells and which measures both living and dead cells?
13. What is a chemostat?
Chapter 5: Microbial Control
1. What is the difference between bactericidal and bacteriostatic?
2. What is the difference between sterilization and disinfection?
3. How are disinfectants different from antiseptics?
4. How did Joseph Lister and Ignatz Semmelweis contribute to the understanding of
microbial control?
5. What parts of an organism are the most sensitive to some type of control?
6. In choosing some type of microbial control, what two main factors are important to
consider? Are all organisms equally sensitive?
7. Understand how each of the following physical methods control bacteria: Heat (dry
heat, boiling, autoclaving, pasteurization), filtration, freezing, dessication, radiation
(ionizing radiation, non-ionizing radiation, and microwaves).
8. Understand how the following types of chemicals control bacteria: Phenol/phenolics,
halogens (iodine and chlorine), alcohols, metal compounds (silver, mercury), soaps,
quaternary ammonium compounds, and biguanides.
9. What technique would you use to control the growth of organisms in the following
situations:
-plastic petri plates
-drinking water
-nutrient agar media
-surface of lab benches
-open wound/cut
-skin before injection
-sterilize a heat sensitive solution
Chapter 31: Food Microbiology
*Also review Chapter 24 (Diseases of the Lower Digestive System) p 584-6594,
Chapter 16 , section 16.5, 16.6, 16.8.
1. Know what the good things bacteria can do to food, the ugly things bacteria do to
food, and the bad.
2. What role do the following microbes have in food production: lactic acid bacteria.
Yeast, and molds?
3. Understand how these factors can influence microbial growth in foods: temperature,
pH, water availability (water activity value aw), atmosphere (O2 available), nutrient
content, antimicrobial constituents, and biological structures.
4. What is meant by the terms food borne intoxication and food borne infection?
5. Know how Staphylococcus aureus and Clostridium botulinum cause food poisoning.
6. Understand how the following organisms can cause food poisoning: Campylobacter
jejuni, Salmonella, Salmonella serotype Typhi, Salmonella serotype Paratyphi,
Shigella, Vibrio cholerae, Vibrio parahemolyticus, Vibrio vulnificus, Listeria
monocytogenes, Clostridium perfringens, and the different types of E. coli mentioned
in lecture.
For each organism covered in class be able to discuss
a. the general characteristics of each organism
b. how a person is exposed to the organism (what type of food is the common
vehicle?)
c. the duration of time before symptoms are seen and the type of symptoms caused
by ingestion of the microbe
d. the mechanisms of pathogenesis for the organism, any unique toxins made by the
organism
e. any treatments for the pathogen