AQA GCSE Biology Unit B3 Chapters 3.2 onwards (Biotechnology)

bits i've collected about microbiology in particular biotechnology.

Not overly interesting but kinda informative...?

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Biotechnology is the use of micro-organisms to make useful products

For example:

  • Food Production (e.g. brewing, yoghurt and cheese making)
  • Antibiotics
  • Biogas
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Yoghurt making


  • Bacteria are added to warmed milk
  • The milk sugar (lactose) is fermented by the bacteria, producing lactic acid
  • The lactic acid causes the milk to solidify (clot) and yoghurt is formed.


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Fleming and the discovery of penicillin

Alexander Fleming left some plates where he was culturing Staphylococcus bacteria uncovered. He noticed clear areas aroung some of the mould that had contaminated the culture and concluded that the mould must have been releasing something that would stop bacterial growth. He managed to grow a pure culture of the mould and discovered that it was Penicillium. However, he couldn't extract very much of the penicillin and it was also very unstable once he had it so he later gave up.

Florey and Chain managed to extract enough penicillin to run tests. They did animal trials before trying it out successfully on a person.

However WW2 meant that all of the British factories were being used to make munitions so Florey and Chain had to go to America to develop an industrial manufacturing process.

Not needed to be known back to front but you should be able to analyse the case study.

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Biogas generators take in waste material or plants, and biogas and useful fertilisers come out the other end.

IN: Dung from people and animals, farm waste, garden rubbish

OUT: Methane for cooking, heating or refrigeration and slurry which can be used as a fertiliser

Biogas is a flammable mixture of gases (mainly methane) formed when bacteria break down plant material or the waste products of animals in anaerobic conditions

As well as burning well, biogas is carbon neutral and gets rid of much of the waste we produce. Also, since they are cheap, they can be used effectively in developing countries. They also work well in hot countries, because they don't need to be insulated to keep the bacteria working well.

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Commonly used plants for gasohol are sugarcane and maize. Plants produce carbohydrates (e.g. sugars and starch) when they photosynthesise. We can extract these sugars or turn the starch into sugar using amylase. These sugars can then be fermented by enzymes. The yeast respires anaerobically and produces ethanol (alcohol) which we can extract by distillation.

Pure ethanol burns very well and is clean and renewable. However, it uses up a lot of land that could have been used for food production or wildlife.


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Olivia Gordon


good and accurate... thanks



Niice set of notes you got there. I was abit unsure about the biogas section of B3... until your notes that is... 5 Stars



Cheers for this mate, it's not long before my retake, and i've been seriously struggling with B3!

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