Required practical: micro organisms

Question 1

Ways of culturing bacteria

Answer 1

Nutrient broth solution
Use Agar gel plate

Question 2

Why use Agar gel?

Answer 2

Because bacteria grows in visible colonies

Question 3

Step 1

Answer 3

Sterilise the Petri dish, the agar jelly and the bench with disinfectant solution

Question 4

Step 2

Answer 4

Sterilise inoculating loop passing it through a Bunsen burner flame
Inoculating loop = how we transfer bacteria

Question 5

Step 3

Answer 5

Open this sterile agar gel plate near a Bunsen burner flame = kills air bacteria

Question 6

Step 4

Answer 6

Use loop to spread chosen bacteria evenly over agar gel plate

Question 7

Step 5

Answer 7

Place sterile filter paper discs with antibiotic onto the plate

Question 8

Step 6

Answer 8

Tape lid of dish using tape to prevent unwanted microorganisms entering

Question 9

Step 7

Answer 9

Place plate upside down to stop moisture dripping down on bacteria and disrupting colonies

Question 10

Step 8

Answer 10

Incubate agar plate at 25°c
To reduce chances harmful bacteria grow

Question 11

Step 9

Answer 11

Over a few days the layer of bacteria would have grown but formed circles around antibiotic filter paper

Question 12

Some of inhibition

Answer 12

Region Where bacteria didn’t grow around antibiotic

Question 13

How to measure affect of antibiotic?

Answer 13

Calculate area of zone of inhibition
Pi x r^2