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Flashcards in B6 - Useful microorganisms Deck (23):
1

What is bacteria used to make?

- yoghurt when milk is turned sour by bacteria
- silage when grass is fermented
- cheese when milk uses bacteria to help it ripen
- vinegar when bacteria make acids from alcohol
- compost when bacteria breaks down dead plant material

2

How do we know yeast is alive?

It needs food and water to grow.

3

When yeast breaks down sugar what does it turn it in to?

Alcohol and carbon dioxide.

4

What is fermentation?

Fermentation is turning sugar into alcohol.

5

Why is fermentation a special kind of respiration?

It does not require oxygen.

6

What are the five stages in the production of yogurt?

1) milk is pasteurised
2) milk is cooled down
3) a bacterial culture is added to the milk
4) samples are taken to find out when the yoghurt is ready
5) flavors and colors are added

7

Why is fermentation anaerobic respiration?

It doesn't use oxygen:
glucose = ethanol + carbon dioxide

8

What is the bacteria called that is used to make yoghurt?

The bacteria is called Lactobacillus.

9

What does Lactobacillus do?

Lactobacillus converts the lactose into lactic acid.

10

What is the chemical symbol for ethanol?

The chemical symbol for ethanol is C2H5OH.

11

Write down the balanced symbol equation for fermentation.

C6H12O6 = 2C2H5OH + 2CO2

12

Why does fermentation require no oxygen?

To ensure that yeast produces alcohol rather than carbon dioxide and water.

13

Why do spirits have a higher concentration of oxygen?

Some of the water has been removed.

14

Name one drink made by the process of fermentation.

Beer
OR
Wine

15

What is beer made from?

Beer is made from barley grains.

16

Why is the alcohol content of beer low compared to spirits?

Beer contains a lot more water.

17

What is distillation?

Distillation is using evaporation and condensation to increase the alcohol content in drinks.

18

What are the two stages of distillation?

- the mixture is heated to evaporate the alcohol
- the alcohol is cooled then turned back into a liquid

19

Describe how beer is clarified.

A chemical is added to make the yeast settle out.

20

What is pasteurisation?

Pasteurisation is the method of preserving beer.

21

What is a yeast strain?

Yeast strains are different varieties of yeast.

22

Why do brewers use different yeast strains?

They tolerate different levels of alcohol.

23

Why is it important to pasteurise beer before bottling it?

To remove any unwanted microorganisms.