Culturing Microorganisms Practical Review

Flashcards covering key questions and answers from the lecture notes on culturing microorganisms practical, including sterilization, incubation, and measuring effectiveness of antibiotics/antiseptics.

What is the purpose of the culturing microorganisms practical?

To investigate the effect of antibiotics or antiseptics on bacterial growth.

Why must Petri dishes and culture media be sterilised before use?

To kill unwanted microorganisms and prevent contamination.

How are inoculating loops sterilised?

By passing them through a flame until red hot.

Why is the lid of the Petri dish secured with tape?

To stop it from accidentally coming off and releasing microorganisms.

Why should the lid not be completely sealed?

To allow oxygen to enter, preventing harmful anaerobic bacteria from growing.

At what temperature should cultures be incubated in schools?

At 25
R
C.

Why is 25
R
C used in school labs?

Because higher temperatures encourage the growth of harmful pathogens.

What is the name of the clear area around an antibiotic disc where bacteria have not grown?

The inhibition zone.

How do you calculate the area of an inhibition zone?

Measure the diameter and use the formula: Area=
R
r2

How is the effectiveness of different antibiotics/antiseptics compared?

By comparing the sizes of the inhibition zones
R
larger zones indicate more effective treatment.

Why is aseptic technique important in this practical?

To ensure only the chosen microorganism is cultured, avoiding contamination and risk to health.

Which part of the AQA spec covers this practical?

Cell biology
R
Required practical: Culturing microorganisms.