Aseptic techniques

Question 1

Why must petri dishes be sterilised before use ?

Answer 1

1) To kill any unwanted microorganisms already present
2) So bacteria grown will only be from intended source and won’t be contaminated

Question 2

Why are petri dishes stored upside down ?

Answer 2

1) Petri dishes are incubated upside down to prevent condensation
2) and to stop disrupting the growth of bacterial colonies.

Question 3

Why are petri dishes incubated at 25 degree Celsius ?

Answer 3

To help intended microbes grow without letting harmful ones that thrive in heat grow.

Question 4

Why are petri dishes secured with tape ?

Answer 4

1. Prevent the lid from opening
2. To lower the chance of germs or dust getting in and causing contamination