Week 3 P2 Sterilisation Y

Question 1

Compare disinfection and sterilisation

Answer 1

Disinfection removes all bad microbes
Sanitisation reduces the number of microbes e.g antiseptic

Question 2

Some factors affecting the influence of killing microbes

Answer 2

Temperature, size, composition, concentration, exposure

Question 3

Dead cell

Answer 3

A cell that can’t divide under conditions that give growth

Question 4

Name physical methods of sterilisation

Answer 4

Heat
Filtration
Radiation

Question 5

To raise BP of water you must

Answer 5

Raise the pressure

Question 6

Tyndallisation definition

Answer 6

Type of sterilisation, boiling goods in cans/jars at BP for 15-20mins for 3 days in a row, kills endospores and MO

Question 7

What is the D value

Answer 7

The time taken under defined conditions to reduce a
population by 90%

Question 8

What is pasteurisation

Answer 8

Use of mild heat to decrease microbial population

Question 9

Autoclaves

Answer 9

Type of pasteurisation, removes air from chamber adds steam to reach desired temp + Pressure

Question 10

Membrane filters uses :

Answer 10

Sterilisation, samples vols of Liq, supports growth of bacteria

Question 11

Bacterial and Fungicidal

Answer 11

Kills B and F both

Question 12

Bacteriolytic

Answer 12

Kills organism and disrupts membranes

Question 13

Bacterio and fungistatic

Answer 13

Stops growth

Question 14

Phenolics adv + dis

Answer 14

long lasting , kills tb dis; toxic , accumulative

Question 15

What technique could we use to sterilise liquid media containing heat sensitive components?

Answer 15

Filtration

Question 16

In an autoclave heat sterilisation is achieved under a temperature of ————– and for a minimum recommended duration of …………………..

Answer 16

121 for 15 mins

Question 17

Pasteurisation can be carried out at:

Answer 17

63 for 30 mins

Question 18

The most difficult problem in sterilization is to kill

Answer 18

endospores

Question 19

The bacterium that is currently under investigation for it’s possible role in Crohn’s disease and spread via milk is:

Answer 19

myobacterium paratuberculosis

Question 20

Heat sterilization is normally undertaken in an autoclave. The most usual conditions are:

Answer 20

15mins 121 degrees

Question 20

In phototrophic metabolism light energy leads to electron generation and electron flow. These electrons are mainly produced from

Answer 20

Water

Question 21

Describe moist heat

Answer 21

Affects microbial growth by disrupting membrane and denaturing proteins

Question 22

How does UV cause MO death

Answer 22

Damages DNA and modifies thymine dimers which causes mutations during repair

only really used with liquids

Question 23

How does ionising radiation cause MO death

Answer 23

Uses gamma rays which cause oxidation

This causes uncontrollable reactions which damage the cell

Question 24

Describe a radical and how it causes microbial death

Answer 24

Highly reactive molecule with unpaired e-s seeking stability

kills microbes by oxidising proteins which affects structure, consequence is that enzymes will lose their activity

Question 25

Bacteriocydial

Answer 25

Kills organism

Question 26

bacteriolytic

Answer 26

kills and disrupts membrane

Question 26

bacteriostatic

Answer 26

inhibits growth