Investigate the antimicrobial properties of plants (9)

Question 1

Why are bacteria mixed in agar before placing it in petri dish?

Answer 1

Bacteria can be distributed evenly, agar is a source of nutrient

Question 2

Explain why petri dish shouldn’t be completely sealed with sticky tape.

Answer 2

Allow some oxygen to enter so bacteria can respire aerobically
Not encouraging development of harmful anaerobic bacteria

Question 3

Suggest suitable temperature for bacteria to grow and explain why

Answer 3

Lower than body temperature, e.g. 20 C so that optimum temperature for its enzymes aren’t the same as body temperature, reduced growth

Question 4

Describe how the antimicrobial properties of the seeds of the Jatoba plant could be tested.

Answer 4

1)Mix bacteria with agar jelly and place in petri dish
2)Sterilizing equipment with disinfectant while wearing gloves
3)Place extract of seeds in same sized paper discs
4)Place discs with extract as well as a control (one with solvent only) in the agar jelly
5)Incubate at 20 C for 1 day
6)Measure zone of inhibition the day after and repeat the experiment 3 times for reliability