1. Which of the following best describes the pattern of microbial death? A. All

Question

1. Which of the following best describes the pattern of microbial death?
A. All the cells in a culture die at once.
B. The pattern varies depending on the antimicrobial agent.
C. The pattern varies depending on the species.
D. Not all of the cells in a culture are killed.
E. The cells in a population die at a constant rate.

QUESTION 2
Which of the following pairs of terms is mismatched?
A. surfactant — removes microorganisms through polar interactions
B. desiccation – loss of water from cells
C. tincture- alcohol extract of a compound
D. sterile — no infectious particles are present on object
E. bacteriostatic — kills vegetative bacterial cells

QUESTION 3
Controlling bacterial growth is difficult, and often wet heat is the best disinfectant/sterilant. Which of the following is a limitation of the autoclave?
A. It cannot be used with glassware.
B. It cannot kill endospores.
C. It cannot be used with heat-sensitive materials.
D. It requires an excessively long time to achieve sterilization.
E.It cannot inactivate viruses.

QUESTION 4
• Which concentration of ethanol is the most effective bactericide?
A. 100 %
B. 70 %
C. 50 %
D. 40 %
E. 30 %

QUESTION 5
An iodophor is a(n)
A. slow-released iodine mixed with a surfactant.
B. quarternary ammonium compound.
C. form of formaldehyde.
D. phenol.
E. agent that reduces oxygen.

QUESTION 6
• Which of the following are factors that affect microbial death by chemical?
A. Number of microbes to start with
B. The environment the bacteria are in
C. The time of exposure to the chemical
D. The microbe’s own characteristics
E. ALL of these effect death by chemical

Explanation / Answer

1. The answer is E. The cells in a population die at a constant rate.

Explanation

When the treatment is applied for each minute, 90% of the remaining population is killed every time. So it is constant.

2. The answer is E. Bacteriostatic

Explanation

Bacteriostatic stops bacteria growing and they also down or stops reproduction in bacterial cells.

3. The answer is C. It can not be used with heat sensitive material.

Explanation

Autoclaving is carried at 121°C so, heat sensitive material gets denatured at high temperature.

4. The answer is 70%

Explanation

Optimum concentration is 70% because pure ethanol is less effective then aqueous solutions as denaturation requires water.

5. The answer is A. Iodophore

Explanation

Iodophore is a group of disinfectant containing iodine in combination with surfactants.

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