aseptic techniques

Question 1

define aseptic

Answer 1

working in sterile conditions to prevent contamination

Question 2

in aseptic techniques what 2 things are you trying to prevent contamination of

Answer 2

• agar plate
• people and the environment

Question 3

what are the 3 steps to working aseptically

Answer 3

• pre inoculating
• inoculation
• post inoculation

Question 4

give examples of what you would do in the pre inoculating stage

Answer 4

sterilise any equipment

wash hands

sterilise tables

Question 5

give examples of what you would do in the inoculating stage

Answer 5

put plate close to bunsen which creates a convection current

open petri dish towards bunsen and place petri dish close to bunsen

flame the lid of the bacterial broth solution

Question 6

give examples of what you would do in the post inoculating stage

Answer 6

disinfect equipment

wash hands

Question 7

why do you sellotape a cross on the petri dish

Answer 7

allows oxygen to enter the petri dish

if you didn’t allow oxygen in you would grow anaerobic bacteria which is very dangerous

Question 8

give 2 reasons why you incubate the petri dish at 25 degrees celsius

Answer 8

• so we don’t grow potentially harmful microorganisms
• bacteria grows more slower

Question 9

give the reason why the petri dishes are stored upside down in the incubuator

Answer 9

prevents condensation on sample so instead it is on the lid preventing the contamination of the sample

Question 10

how do you perform serial dilutions of bacteria culture

Answer 10

0.1
add 9 cm cubed sterile water to 1cm cubed bacterial culture

0.01
add 9cm cubed sterile water to 1cm cubed of previous solution

0.001
add 9cm cubed sterile water to 1cm cubed of previous solution