Required Practical 6 - Use of aseptic techniques to investigate the effect of antimicrobial substances on microbial growth.

Question 1

State 6 aseptic techniques.

Answer 1

• Wipe down surfaces with antibacterial cleaner before and after experiment.
• Use a bunsen burner in the work space so convection current draws microbes away from culture.
• Flame the wire hoop before using it to transfer bacteria.
• Flame the neck of any bottles before using the, to prevent any bacteria entering the vessel.
• Keep all vessels contain gin bacteria open for the minimum amount of time.
• Close windows and doors to limit air currents.

Question 2

How can you compare the effectiveness of different antibiotics applied to the same bacteria.

Answer 2

• Measure the diameter and calculate the area of the zone of inhibition on the agar.

Question 3

State the hazards and precautions of this practical.

Answer 3

• Naked flame - keep away from flammable materials, tie hair up and wear goggles.
• Bacteria is a biohazard - use disinfectant and wash hands, dispose of bacteria safely.
• Disinfectant is flammable - keep away from naked flame.

Question 4

Why should the lid not be completely taped to the petri dish.

Answer 4

• To allow oxygen to enter and prevent growth of harmful anaerobic bacteria.