Microbiology - chapter 7

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Microbiology
Chapter 7
updated 4 years ago by marciacaroline
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1

Which is the best method to sterilize heat-labile solutions?

membrane filtration

2

Which best describes the pattern of microbial death?

The cell in a population die at a constant rate

3

Which chemical agents is used for sterilization

ethylene oxide

4

Which substances is used for surgical hand scrubs?

Chlorhexidine

5

Which of the following antimicrobial control agents statement are TRUE

a) contaminating organic debris such as blood or sputum decrease effectiveness

b) some agents kill by denaturing microbial cell proteins

c) some agents affect microbial cell membranes by dissolving lipids

d) silver is used for treating antibiotic-resistant bacteria

6

Which of the following does achieve sterilization?

a) dry heat

b) autoclave

c) supercritical fluids

d) ethylene oxide

7

Which of the following does NOT achieve sterilization?

pasteuralization

8

Which is a limitation of the autoclave?

It cannot be used with heat-labile materials

9

An agent to reduce bacteria on a toilet would be called

desinfectant

10

Applying heat to living cells can result in

a) breaking of hydrogen bonds

b) alteration of membrane permeability

c) denaturation of enzymes

c) damage to nucleic acids

11

Which disinfectants act by disrupting the plasma membrane?

bisphenols

12

All substances are effective against noenveloped viruses

a) chlorine

b) ethylene oxide

d) ozone

13

Which method is used to preserve food ?

Freezing

14

Which concentration of ethanol (alcohol) is the most effective bactericide?

70 percent

15

All factors contribute to hospital acquired infection

a) some bacteria metabolize disinfectants

b) gram-negative bacteria are often resistant to disinfectants

b) invasive procedures can provide portal of entry for bacteria

d) bacteria my be present in commercial products such as mouthwash

16

Which of the treatments are the most effective for controlling microbial growth?

a) 63o C for 30 min

b) 72oC for 15 sec

c) 140o C for 4 sec

17

Which method could be used to sterilize plastic Petri plates in a plastic wrapper?

gamma radiation

18

Which results in lethal damage to nuclei acids?

a) heat

b) radiation

c) some chemicals

19

All of the following are effective for destroying PRIONS

a) incineration

b) NaOH + autoclaving at 134oC

c) proteases

20

All of the following are methods of food preservation

a) desiccation

b) high pressure

c) ionizing radiation

d) osmotic pressure

21

If you were preparing nutrient agar at home and did nota have an autoclave, what could you use to sterilize the nutrient agar?

pressure cooker at 121o C for 15 minutes

22

Which one of the following is most resistant to chemical biocides?

gram-negative bacteria

23

The thermal death times is the time needed to kill all the bacteria in a particular culture at a certain temperature

True

24

Moist heat destroys organisms by denaturing proteins

True

25

The PH of the medium has no affect on the activity of the disinfectant being applied

False

26

Autoclaving is the most effective method of moist heat sterIlization

TRUE