Name
Date
Home Work 3
1. When will most antibiotics have the greatest inhibitory effect?
a. Lag Phase
b. Log Phase
c. Stationary Phase
d. Death Phase
____ Oxygen is toxic and inhibitory
2. Match the following:
a. Obligate Aerobes
____ Requires oxygen to replicate
b. Facultative Anaerobes
____ Grow better in Oxygen
c. Obligate Anaerobes
environments but not required
3. Reactive Oxygen Species:
a. Require special enzymes to neutralize in Aerobic bacteria
b. Are formed by Obligate Anaerobes in the absence of oxygen
c. Are only toxic to Obligate Aerobes
4. Why do organisms need nitrogen?
5. Where do Chemoorganoheterotrophs get their carbon?
6. Which of the following factors influence bacterial growth in food?
a. pH
b. Availability of water
c. Presence/Absence of oxygen
d. Surrounding rinds, shells, membranes or skins
e. All of the above
7. Enterotoxin is produced by Staphylococcus aureus and is referred to as a super antigen. What
does that mean?
a. Super antigens confer resistance to antibiotics
b. Super antigens can activate T cells, even with the wrong proteins present
c. Super antigens cause epithelial cells to secrete growth factors bacteria can use
d. Super antigens function as attachment and adhesion molecules
8. What does the Shiga Toxin do?
a. Inhibits cell division
b. Inhibits protein synthesis
c. Neutralizes the gastric pH of the stomach
d. Suppresses the normal gut flora
9. How does Helicobacter pylori deal with the low pH of the stomach?
10. Which organism poses the greatest danger in canned foods?
a. Helicobacter pylori
b. Escherichia coli
c. Clostridium botulinum
d. Staphylococcus aureus
11. Match the following:
_____ STEC
a. Traveler’s diarrhea, attaches to intestinal wall via a pili
b. Produces Shiga-like Toxin, includes O157:H7 strain, can lead to Hemolytic Uremic _____ EPEC
Syndrome
_____ETEC
c. Accounts for 20% of diarrhea incidence in developing world infants
Lab Questions
12. What does the OD (Optical Density) measure
a. The number of bacteria in a culture
b. The relative turbidity of a culture
c. The concentration of nutrients in the media
d. The viability of a sample
13. Why would you inoculate slants instead of standard tubes?
14. Which organisms grow where?
a. Obligate Anaerobes
b. Obligate Aerobes
c. Facultative Anaerobe
15. Describe how each type of selective media works
Tripticase Soy Agar
Eosin Methylene Blue Agar
Glucose Mineral Agar
____ Slants
____ Deep Agar
____ Uniform throughout media