RP06 - Aseptic techniques

Question 1

State 4 aseptic techniques

Answer 1

• Wash hands to kill microbes
• Disinfect work bench to kill microbes
• Flame instruments to kill microbes
• Lift lid slightly to prevent entry of microbes

Question 2

Why is bacteria incubated at 25C

Answer 2

To prevent the growth of pathogens, which occurs at high temperature

Question 3

How can you measure effectiveness of different antibiotics applied to same bacteria

Answer 3

Measure the diameter and calculate the area of the zone of inhibition (clear zone) on the agar

Question 4

What does the zone of inhibition indicate

Answer 4

• It indicates the bacteria killed by antibiotics
• The larger the zone the more effective the antibiotics
• If an antibiotic has very little or no zone of inhibition, the bacteria is likely resistant to the antibiotic

Question 5

State hazards and precautions

Answer 5

• Naked flame- hair tied and goggles
• Bacteria is a biohazard - wash hands
• Disinfectant is flammable - keep away from naked flame

Question 6

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

Answer 6

To allow oxygen to enter petri dish, preventing growth of harmful anaerobic bacteria

Question 7

Describe the graph that can be plotted from the results of this practical

Answer 7

A bar graph of zone of inhibition