Test 5

Question 1

During which phase of the bacterial growth curve are cells typically most resistant to inhibitory factors?

a. lag phase
b. log phase
c. stationary phase
d. death phase
e. phasecontrast

Answer 1

c. stationary phase

Question 2

The time required for a microbial cell population to increase from 1 million to 2 million is referred to as the:

a. incubation time
b. generation time
c. exponential time
d. regulation time
e. critical time

Answer 2

b. generation time

Question 3

The major source of Vitamin K for humans is:

a. collard greens
b. kale
c. red meat
d. amino acid
degradation
e. E. coli

Answer 3

e. E. coli

Question 4

Which of the following bacteria is an exception to the general rule that most bacteria will not grow below pH 4.5?

a. Lactobacillus acidophilus
b. E. coli
c. Staphylococcus aureus
d. Saccharomyces cerevisiae
e. Clostridium botulinum

Answer 4

a. Lactobacillus acidophilus

Question 5

Assume that raw ground beef has been left on the kitchen counter and has reached room temperature. If the initial population of Pseudomonas in the ground beef is 104 CFU/g, and the generation time is 12.1 minutes, how
long would it take for the population to reach 108 CFU/g?

a. 30 min
b. 2 hrs
c. 6 hours
d. 240 min
e. 2 hrs, 40 min

Answer 5

e. 2 hrs, 40 min

Question 6

The pH at which an organic acid is in equal proportions of the dissociated and un-­dissociated forms is the:

a. isoelectric point
b. resonance point
c. alpha acid
d. pKa
e. acid/base conversion point

Answer 6

d. pKa

Question 7

What form of an organic acid is the most effective anitmicrobial?

Answer 7

un-dissociated form

Question 8

For high acid foods, what factors limits the functionality of organic acids?

Answer 8

solubility

Question 9

Food with a pH less than 4.6 are considered:

Answer 9

high acid foods

Question 10

Which of the following has the highest pH?

a. lemons
b. egg yolk
c. post rigor meat
d. milk
e. egg whites

Answer 10

egg whites

Question 11

Which of the following foods would have the highest buffering capacity?

a. potatoes
b. spinach
c. orange juice
d. ground beef
e. chocolate

Answer 11

ground beef

Question 12

Which of the following foods would have the lowest Eh?

a. ground beef
b. post rigor meat
c. chicken
d. milk
e. cheese

Answer 12

cheese

Question 13

Which of the following is a polyhydric alcohol?

a. ethanolamine
b. sorbitol
c. avidin
d. tequila
e. wine

Answer 13

sorbitol

Question 14

The naturally occuring antimicorbial, conalbumin, inhibits bacterial growth by:

Answer 14

binding with iron

Question 15

Polyhydric alcohols are added to foods for what purpose?

Answer 15

to lower the water activity

Question 16

What foodborne pathogen can tolerate the lowest water activity?

Answer 16

Staphlyococcus aureus

Question 17

Which of the following would grow in honey?

a. Clostridium botulium
b. Zygosaccharomyes rouxii
c. Xeromyces bisporus
d. Staphylococcus aureus
e. Apis mellifera

Answer 17

Zygosaccharomyes rouxii

Question 18

Bacterial soft rot of vegetables is caused by:

Answer 18

Erwinia carotovora

Question 19

What glycoprotein found in egg’s albumin binds with biotin?

Answer 19

avidin