Practical 6

Question 1

state 6 aseptic techniques

Answer 1

wipe down surfaces with antibacterial cleaner, before and after experiment
use bunsen burner in the work space so that convection current Dra 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 25c

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 inhibition on the agar

Question 4

what does the zone of inhibition indicate

Answer 4

indicates the bacteria killed by the antibiotic

Question 5

state the hazards and precautions of this practical

Answer 5

naked flame: keep away from flammable materials, tie up hair, wear goggles
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 cart of zone of inhibition against the antibiotic