Culturing micro-organisms

Question 1

State the stages of growing bacteria

Answer 1

Pre-inoculation
Inoculation
Post-inoculation

Question 2

DESCRIBE pre-inoculation

Answer 2

Preparing apparatus

Question 3

How to prevent contamination in pre-inoculation:

Answer 3

Sterilise petri dish, agar jelly, work bench
Pass inoculating loop over flame to sterilise

Sterilising kills unwanted micro-organisms or pathogens so the bacteria is not contaminated

Question 4

DESCRIBE inoculation

Answer 4

use the inoculating loop to transfer bacteria to the petri dish

Question 5

How to prevent contamination in inoculation:

Answer 5

work close to an open flame to create updraft
open petri dish lid as little as possible

this blocks/prevents airborne micro-organisms from contaminating the culture

Question 6

DESCRIBE post-inoculation

Answer 6

place and store the petri dish in an incubator

leave it in to allow for the bacteria to grow

Question 7

How to prevent contamination in post-inoculation:

Answer 7

tape a lid on the petri dish (prevents airborne micro-organisms from entering)
store petri dish upside-down (to prevent condensation falling onto the agar surface)
place in an incubator at no higher than 25 degrees (to prevent any harmful pathogens from developing/growing)