S3 Micro-organisms

S3 Micro-organisms

Microorganisms are small single celled living things. 

The main groups of micro-organisms are bacteria and fungi. 

Microorganisms are useful to humans for a number of reasons including; 

• They grow very quickly

• They use many different types of food

• They produce a wide range of products. 

Multiple Choice

Micro-organisms are...

• single celled

• multi celled

Multiple Choice

which of the following is NOT a benefit of microorganisms?

• They use many different types of food

• They produce a wide range of products

• They don't require a food source

• They grow very quickly

Bacteria

Yoghurt making 

Some bacteria are added to milk to make yoghurt.

The bacteria feed on the lactose sugar in milk to make lactic acid.

This lactic acid thickens the milk and makes it sour to give yoghurt its characteristic taste and texture. 

Cheese making

bacteria are added to milk (along with the enzyme rennet) to make cheese. 

Multiple Choice

Which of the following is not made by bacteria

• bread

• cheese

• yogurt

Multiple Choice

What do bacteria get added to in the production of yogurt?

• cheese

• rennet

• milk

Multiple Choice

What do the bacteria produce when they feed on sugar?

• rennet

• lactic acid

• yeast

Yeast (a fungus) 

Yeast is a fungus which can use sugar as a source of energy. It produces carbon dioxide and alcohol as waste products during this reaction.

Breadmaking 

Yeast produce carbon dioxide which is used in dough to make the dough rise.

Baking also gets rid of the alcohol which evaporates off. 

• Beer and wine making 

• Yeast feeds on sugar and makes alcohol. 

Biofuels

are fuels made from crop plants. The are renewable.

 

Ethanol is a biofuel which is manufactured by converting starch into sugar. This sugar is then turned into alcohol (ethanol) by using yeast.  

 

The ethanol produced can be used to power cars.  

Multiple Choice

Yeast is an example of a...

• bacteria

• fungus

Multiple Choice

What does yeast use as its source of energy when making beer?

• ethanol

• flour

• biofuel

• sugar

Multiple Choice

What helps to make bread rise?

• carbon dioxide

• ethanol

• sugar

• oxygen

Multiple Choice

What happens to the ethanol when you bake bread?

• It condenses

• It evaporates

• It gets turned into Carbon Dioxide

• It goes into the bread

Multiple Choice

Biofuels are produced from...

• sugar

• alcohol

• crop plants

• carbon dioxide

Multiple Choice

Which of the following is an example of a biofuel

• bread

• ethanol

• coal

• carbon dioxide

Multiple Choice

biofuels are...

• renewable

• non-renewable