B6c: Useful Micro-Organisms

As we begin to understand how microorganisms work, we can develop new ways of using them as well as making existing processes more efficient.

  

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Name five process that bacteria are useful in?
Composting, yogurt making, cheese, vinegar and silage making.
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Describe fermentation
The production of alcohol by the breakdown of sugars by yeast in the absence of oxygen.
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Name two products of fermentation.
Beer and Wine
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What gas is produced during fermentation?
Carbon Dioxide
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What can happen to some products after fermentation?
They can be treated further to increase the alcohol concentration to produce spirits.
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Describe the process of how to make yogurt.
Equipment is sterilised, milk is pastured by heating, bacteria culture is added to the cooled milk and left at 46°C for about four hours, samples are taken to see if the yogurt is ready, flavours and colours are added, yogurt is packaged
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What is the bacteria used in making yogurt?
Lactobacillus
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What sugar is there in milk?
Lactose
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What does the bacteria in yogurt do?
Lactobacillus is able to break lactose down to form lactic acid. The lactic acid both lowers the pH of the yoghurt, which helps to preserve it, and denatures milk proteins, which gives the yoghurt its sharp taste.
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What is the word equation for fermentation?
Glucose (sugar) = Ethanol (alcohol) + carbon dioxide
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Describe the main stages in brewing wine/beer (F = fermentation)
Sugar extracted from plants,yeast added-mixture kept warm,air&other microorganisms kept out of container using air lock,F allowed to continue(CO2 helps keep air out),mixture is clarified by settling&filtration,drink pasteurised,stored in casks/bottle
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What is the balanced symbol equation for fermentation?
C˅6H˅12O˅6 → 2C˅2H˅5OH + 2CO˅2
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What is pasteurisation?
When the drink is treated to kill most bacteria by heating to below boiling point for a short amount of time.
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What is fermentation an example of?
Anaerobic respiration in yeast
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Why does beer need to be pasteurised and then bottled?
Because it has a low percentage of alcohol, so it has to be pasteurised to kill any harmful microorganisms it might contain.
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What are the implications of fermentation using yeast?
Yeast can undergo aerobic and anaerobic respiration
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Talk about yeast using respiration in bread making.
the yeast starts off respiring aerobically, producing water and also carbon dioxide to make the dough rise. When the air runs out, the yeast begins to respire anaerobically. Any alcohol produced boils away during baking.
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Talk about yeast using respiration in alcohol making.
east establishes an oxygen-free environment - provided no air is allowed to enter the fermentation container.
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How can the concentration of an alcohol drink be increased?
By distillation.
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What sort of process is distillation of alcohol? Explain.
istillation of alcohol is a commercial process. The places where it is done must be licensed. It is legal to make beer and wine at home, but not spirits.
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Why does distillation work?
because ethanol has a lower boiling point than water.
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What can different strains of yeast tolerate?
Different levels of alcohol
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Why is fermentation limited to the concentration of alcohol it can produce?
The ethanol that the yeast cells produce eventually kills them. This limits the concentration of alcohol that can be achieved by fermentation alone.
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Other cards in this set

Card 2

Front

Describe fermentation

Back

The production of alcohol by the breakdown of sugars by yeast in the absence of oxygen.

Card 3

Front

Name two products of fermentation.

Back

Preview of the front of card 3

Card 4

Front

What gas is produced during fermentation?

Back

Preview of the front of card 4

Card 5

Front

What can happen to some products after fermentation?

Back

Preview of the front of card 5
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