Cpac 6: Aseptc Techniques

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 that convection currents draw microbes away from the culture
Flame the wire hoop before using it to transfer bacteria
Flame the neck of any bottles before using them to prevent any bacteria entering the vessel
Keep all vessels containing bacteria open for the minimum amount of time
Close windows and doors to limit air currents

Question 2

Why is bacteria incubated at 25ºc

Answer 2

To prevent the growth of pathogens, which occurs at higher Temperatures

Question 3

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

Answer 3

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

Question 4

What does the zone of inhibition indicate

Answer 4

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

Question 5

State the hazards and precautions of this practical

Answer 5

Naked flame: keep away from flammable materials, tie hair up, wear goggles
Bacteria is a biohazard, use a disinfectant and 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 the Petri dish, preventing the growth of harmful anaerobic bacteria

Question 7

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

Answer 7

A bar chart of zone of inhibition against antibiotic