Biology B3

Biology B3, bits and bobs

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Classical conditioning:

This is when an animal learns passively to associate a 'neutral stimulus' with an important one.  Response is automatic and reinforced by repetetition. E.g. Pavlov's dogs.

Operant conditioning:

This is where an animal learns actively using trial and error to associate a simulus with  a reward or punishment.

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1.  Equipment is sterilised to kill off any harmful microorganisms

2.  Milk is pasterurised (heated to 72 degrees C for 15 secs) to kill off any microgransims.

3. A started culture of bacteria (Lactobacillus) is added. Then the mixture is incubated in a fermenter.

4. Bacteria ferment lactose sugar in milk to form lactic acid.  The lactic acid lowers the PH of the micture

5. The milk protein, casien, coagulates causing the micture to thicken and set.

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Soy Sauce

1. Cooked soy beans and roasted wheat are mixed.

2. Mixture is fermented by Aspergillus fungus. Aspergillus secretes enzymes into the mixture breaking down starch molecules into smaller suger molecules.

3. Yeast and Lactobacillus bacterium are added. This stops Aspergillus secreting enzymes.

4. Mixture is filtered then pasteurised.

5. Mixture is put in sterile bottles.

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Hebicide resistant crops

  • Plant allready resistant to herbicide is found and responsible gene is identified.
  • Herbicide resistant (HR) gene is cut out using restriction enzymes.
  • Agrobacterium Tubefacien plasmid is cut out using restricion enzymes.
  • HR gene is inserted onto sticky ends of plasmid using ligase enzymes.
  • Plasmid is put back into Agrobacterium Tubefacien.
  • Allow bacterium to infect cells of target plant.
  • Bacteria casue a crown gall to grow on the plant. The genetic material of the gall cells will contain the HR gene.
  • Grow a tissue culture of the gall cells in a medium containing the herbicide. Those that grow have the resisitence.
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Production of insulin

  • Gene for human insulin is identified.
  • Gene cut out using restriction enzymes and stuck on to bacterium plamid using ligase
  • Plasmid inserted back into bacterium. Now starts producing insulin. Bacteria grown in a fermenter.
  • Bacteria killed by sterilisation and insulin extracted then purified.
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Bacillus Thuringiensis

  • Produces toxin/pesticide
  • Responsible gene cut out of bacterium
  • Gene put ino plasmid that takes wanted gene into plant cells
  • Gene incorporated into DNA of crop
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Good, but spelling errors affect the MP3 file. Thanks for sharing.

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