B1: CULTURING MICROORGANISMS

Question 1

Aseptic techniques

Answer 1

-sterilising surface
-sterilising equipment (eg: by heating to a high temp)
-passing inoculating loop through a flame
-open bacteria culture slightly
-lid of petri dish secured with tape

Question 2

RP - Microbiology

Answer 2

investigates effects of antiseptics/antibiotics on bacterial growth using agar gel playes and measuring zones of inhibition

-place paper discs soaked in different types of of antiseptic/antibiotic on an agar plate that has an even covering of bacteria
-the antiseptic/antibiotic should diffuse into the agar gel. a clear area will be left where the bacteria have died (inhibition zone)
-leave the plate for 48 hrs at 25°C
-the more effective the antiseptic/antibiotic is against the bacteria the bigger the inhiition zone will be

Question 3

(RP - microbiology) What are the variables?

Answer 3

-IV: antiseptics/antibiotics
-DV: mean diameter of inhibition zones (used to calculate area)
-CVs: temp, time, area of filter paper discs, nutrients in agar

Question 4

What is a control experiment you could use to ensure there was no other factor affecting bacteria growth?

Answer 4

-soak filter paper disc in distilled water
-distilled water should not have an effect on bacterial growth