Aseptic Techniques

Question 1

Autoclave

(1 mark)


Answer 1

Machines for sterilising used apparatus.

Question 2

Culture

(2 marks)


Answer 2

In microbiology, a colony of microbes

• typically on an agar plate.

Question 3

Inoculate

(1 mark)


Answer 3

To introduce bacterial cells.

Question 4

Pathogen 


1 mark

Answer 4

Microorganisms that are harmful to humans.

Question 5

Petri dish

3 marks

Answer 5

A clear glass or plastic dish

• used to grow living cells from organisms so they can be studied.

Question 6

Aseptic techniques

3 marks

Answer 6

Ensure the microorganisms being investigated do not escape or become contaminated with an unwanted microorganism.

• or the growth of unwanted, pathogenic microorganisms.

Question 7

Aseptic techniques include:

9 marks

Answer 7

• No eating/drinking in lab.
• Wiping bench with disinfectant/alcohol.
• Not growing microorganisms at body temp.
• Using sterile loops when transferring cultures.
• Flaming culture bottle necks to prevent contamination.
• Sterilising (using an autoclave)/ disposing of all used equipment.
• Wash hands thoroughly

Question 8

Aseptic Techniques;

Apparatus used

Answer 8

• Culture bottle; Bacteria growing on agar
• Inoculating loop
• Petri dish containing agar
• Bunsen burner

Question 9

Aseptic techniques – in practice

23 marks

Answer 9

Complete with Bunsen burner on bench - kill airborne microorganisms.

• Pass a metal loop through flame (to sterilise).
• Allow to cool; prevent microorganisms it touches being killed.
• Remove culture bottle lid + sweep neck of bottle through the flame to (sterilise)
• Glide metal loop through bacterial culture; will inoculate metal loop with bacteria.
• Sweep neck of the bottle through flame again (sterilise).
• Replace culture bottle lid (prevent contamination).
• Partially lift Petri dish lid; prevent entry of unwanted airborne microorganisms.
• Plating; glide inoculated metal loop over surface of the nutrient agar (agar enriched with nutrients + minerals essential for bacterial growth).
• Pass metal loop through flame again (sterilise).
• Tape the Petri dish lid on.
• Incubate at 25°C – below body temp; ensures pathogenic microorganisms don’t grow. Incubate upside down to avoid condensation dripping on the bacteria.