Biol 2460 Chapter 9

B - total plate count

1. Which of the following methods would be used to measure the concentration of bacteria contamination in process peanut butter?

A - death phase

2. In which phase would you expect to observe the most endospores in a Bacillus cell culture?

C - log phase

3. During which phase would penicillin, an antibiotic that inhibits cell-wall synthesis, be most effective?

B - the length of time it takes for a population of cells to double

4. Which of the following is the best definition of generation time in a bacterium?

B - it forms a contractile ring at the septum

5. What is the function of the Z ring in binary fission?

C - 1600

6. If a culture starts with 50 cells, how many cells will the present after five generations with no cell death?

C - fragmentation

7. Filamentous cyanobacteria often divide by which of the following?

C - cells are metabolically inactive at the base of a biofilm

8. Which is a reason for antimicrobial resistance being higher in a biofilm then in free-floating bacterial cells.

D - the density of the population

9. Quorum sensing is used by bacterial cells to determine which of the following?

A - they bind directly to DNA to activate transcription

10. Which of the following statements about auto-inducers is correct?

B - the organisms are facultative anaerobes

11. An inoculated thioglycolate medium culture tube shows dense growth at the surface and turbidity throughout the rest of the tube. What is your conclusion?

A - the organisms are obligate anaerobes

12. An inoculated thioglycolate medium culture tube is clear without the tube except for dense growth at the bottom of the tube. What is your conclusion?

B - obligate aerobe

13. Pseudomonas aeruginosa is a common pathogen that affects the airways of patients with cystic fibrosis. It does not grow in the absence of oxygen. The bacterium is probably which of the following.

D - an aerotolerant anaerobe

14. Streptococcus mutants is a major cause of cavities. He resides in the gum pockets, does not have (AT) lays activity, and can be grown outside of an anaerobic chamber. The bacterium is probably which of the following?

C - it is a capnophile

15. Why do the instruments for the growth of Neisseria gonorrhoeae recommend a CO2-enriched atmosphere?

B - acidophiles

16. Bacteria that grows in mine drainage at pH 1-2 are probably which of the following?

A - alkaliphiles

17. Bacteria isolated from lake Natron, where the water pH is close to 10, are which of the following?

B - a hot vent at pH 1.5

18. In which environment are you most likely to encounter an acidophil?

D - psychrotrophs

19. A soup container was forgotten in the refrigerator and shows contamination. The contaminants are probably which of the following?

C - mesophiles

20. Bacteria isolated from a hot tub at 39°C are probably which of the following?

C - hydrothermal vent at the bottom of the ocean

21. In which environment are you most likely to encounter a hyperthermophil?

A - a mountain lake with a water temperature of 12°C

22. Which of the following environments would harbor psychrophiles?

D - low water activity

23. Which of the following is the reason jams and dried meats often do not require refrigeration to prevent spoilage?

C - halotolerant

24. Bacteria living in salt marshes are most likely, which of the following?

D - a selective medium, a differential medium, and a complex medium

25. EMB agar is a medium used in the identification and isolation of pathogenic bacteria. It contains digested meat proteins as a source of organic nutrients. Two indicator dyes, rosin and methylene blue, inhibit the growth of gram-positive bacteria and distinguish between lactose fermenting and non-lactose fermenting organisms. lactose fermenters form, metallic, green or deep purple colonies, whereas the non-lactose fermenters form completely colorless colonies. EMB agar is an example of which of the following?

D - fastidious

26. Haemophilus influenza must be grown on a chocolate agar, which is blood agar treated with heat to release growth factors in the medium. H. Influenza is described as.

D - Death Phase

27. Number of dying cells is higher than the number of cells dividing

C - Stationary Phase

27. Number of new cells equal to number of dying cells

A - Lag Phase

27. New enzymes to use available nutrients are induced

B - Log Phase

27. Binary fission is occurring at maximum rate

onligate anaerobes

28-A.

Obligate aerobe

28-B

Microaerophiles

28-C

facultative anaerobes

28-D

Psychotroph

29. Food spoiling in refrigerator

Hyperthermophile

29. Hydrothermal vent

Psychrophile

29. Deep ocean waters

Mesophile

29. Human pathogen

Thermophile

29. Garden compost

Hemocytometer; Petroff-Hausser counting chamber

30. Direct count of total cells can be performed using a ____________ or a __________

Plate count

31. The ____________ method allows direct count of cells growing on solid medium

Most probable number

32. A statistical estimate of the number of life cells in a liquid is usually done by

Turbidity

33. For this indirect method of estimating the growth of a culture, you measure ____________, using a spectrophotometer.

ATP, acid from fermentation

34. Active growth of a culture may be estimated indirectly by measuring the following products of cell metabolism: ___________ or ___________.

Alkaliphile

35. A bacterium that thrives in a soda lake where the average pH is 10.5 can be classified as a(n) ___________

Acidophilus

36. Lactobacillus acidophilus grows best at pH 4.5. It is considered a(n) ___________

Halophile

37. A bacterium that thrives in the Great Salt Lake but not in freshwater is probably a___________

Barophiles

38. Bacteria isolated from the bottom of the ocean need high atmospheric pressure to survive. They are ___________

Halotolerant

39. Staphylococcus aureus can be grown on multipurpose growth medium or on mannitol salt agar that contains 7.5% NaCl. The bacterium is ___________

Complex; differential

40. Blood agar contains many unspecified nutrients, supports the growth of a large number of bacteria, and allows differentiation of bacteria, according to hemolysis, breakdown of blood,. The medium is ___________ and ___________

Complex; selective

41. Rogosa agar contains yeast extract. The pH is adjusted to 5.2 and discourages the growth of many microorganisms; however, all the colonies look similar. The medium is ___________ and ___________