Biolgy quiz SB5k & SB5f

Question 1

What are the steps to creating a bacterial culture and analyzing the results?

Answer 1

1. Take a sterile petri dish (sterilize with steam)
2. Using a sterile wire loop, spread the bacteria on
   agar jelly
3. Add nutrients and cover dish with a lid (sellotape on 2
   sides)
4. Incubate petri dish at 30oC (optimum temp. for
   growth)
5. Let them grow for 2 days
6. Take filter paper discs with antibiotics on them and
   place them on agar
7. Wait for 2 days and measure the zone of inhibition
   (clear zone) – calculate the area of the circle (πr2)
8. The larger the clear zone/zone of inhibition, the
   more effective the drug was (more bacteria killed

Question 2

What is The nutrient agar

Answer 2

agar is a jelly-like substance that contains nutrients such as glucose

Question 3

Why would you want to grow bacteria in the lab?

Answer 3

1. Experiment with them
2. Test chemicals
3. Add viruses
4. Study them

Question 4

What are some Aseptic precautions used while preparing dish?

Answer 4

1. Flame wire loop
2. Flame mouth of containers
3. Heat up agar
4. Antiseptic on bench e.g. alcohol
5. Lid on petri dish with sellotape
6. Steam equipment

Question 5

How do you find the area of the clear zone?

Answer 5

Get a ruler and measure the diameter and divide by 2 for radius