Growing micro-organisms

Question 1

What did Louis Pasteur do that led to the development of aseptic techniques?

Answer 1

He carried out an experiment showing that once micro-organisms are destroyed, they do not suddenly appear again. They can only be transferred from something that contains them- like the air

Question 2

Why do we use aseptic techniques?

Answer 2

They are used to prevent spoilage of food and to prevent infection of wounds in surgery (operation)

Question 3

Describe the growth of bacteria

Answer 3

It grows rapidly by doubling every 20 mins. We describe it as exponential growth

Question 4

What does resazurin dye do?

Answer 4

It is used in the making of yogurt by adding it to milk. It shows whether a substance contains lots of oxygen and little bacteria (appears as a blue colour); some oxygen and more bacteria (pink); or no oxygen and lots of bacteria (colourless)

Question 5

Why would the rate of population growth of bacteria not continue exponentially?

Answer 5

Something will start to limit it (such as nutrient supply)