Investigating selection

Question 1

What is the purpose of aseptic techniques?

Answer 1

To prevent contamination of cultures by unwanted micro-organisms as contamination can affect the growth of the micro-organism that you’re working with or could make you ill

Question 2

Why should you regularly disinfect work surfaces?

Answer 2

To minimise contamination

Question 3

What are some aseptic techniques that should be used?

Answer 3

• Regularly disinfect work surfaces
• Use sterile equipment
• Work near a Bunsen burner
• Minimise the time spent with the lid off the agar plate
• Briefly flame the neck of the glass container of broth just after its opened and just before its closed

Question 4

Why should you work near a Bunsen burner when working with microbes?

Answer 4

Any microbes in the air will be drawn away from your plate

Question 5

Why should you minimise the time spent with the lid off the agar plate?

Answer 5

To reduce the chance of airborne micro-organisms contaminating the culture

Question 6

Why should you briefly flame the neck of the glass container of broth just after its opened and just before its closed?

Answer 6

causes air to move out of the container, preventing unwanted organisms from falling in

Question 7

What is the inhibition zone?

Answer 7

Area where the bacteria has been destroyed

Question 8

What is the purpose of boiling the agar?

Answer 8

To avoid contamination

Question 9

What is the purpose of transferring the same volume of liquid culture onto each agar plate?

Answer 9

To allow for comparison of the effect of different concentrations of disinfectant on the bacteria