Bacteria

Question 0

What did Pasteur do to show that microbes cause decay and disease?

Answer 0

Heated broth in two flasks- one of the necks of the flasks was bent in a way that the microbes settles on the tube before reaching the broth. The broth with the bent neck didn’t go off, showing that it was the microbes that causes food to go off and not the air.

Question 1

How would you describe the growth of bacteria?

Answer 1

Exponential - rapidly increases

Question 2

What process did Louis Pasteur invent?

Answer 2

Pasteurisation

Question 3

What is pasteurisation?

Answer 3

Heating a substance to around 70 degrees (to kill off most harmful bacteria) and then cooling it.

Question 4

What technique is used to reduce contamination by germs?

Answer 4

Aseptic technique.

Question 5

What is Aseptic technique?

Answer 5

Reducing contamination by germs.

Question 6

What can pasteurisation be used to treat?

Answer 6

Raw milk (in order to make it safe to drink)

Question 7

Why can pasteurisation be better than sterilisation for the removal of material for certain products?

Answer 7

If you sterilised raw milk, the more severe form of heat treatment would alter the taste of the milk and would destroy some of it’s vitamins.

Question 8

What is Resazurin Dye?

Answer 8

It is a dye sensitive to the amount of oxygen present.

Question 9

What are the colours of reassuring dye and what do they mean?

Answer 9

Blue- lots of oxygen present
Lilac- some oxygen present
Mauve- a smaller amount of oxygen present
Pink- not much oxygen present
Colourless- very little/no oxygen present

Question 10

How does Resazurin Dye help us see how many microorganisms are present?

Answer 10

Microorganisms use oxygen to respire, and so the colour change in the dye will tell us how many microorganisms are present (the more microbes, the less oxygen)