Biology B6

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  • Many bacteria cause disease but others are used in biotechnology
  • Disease causing microbes can spread in many ways and have to be controlled using antiseptics and antiobiotics
  • Antibiotic use has to be controlled as some bacteria are developing resistance. Viruses are unaffected by antibiotics
  • Bacteria exist in many different shapes but they all reproduce by binary fission and have certain cell structures in common
  • Viruses use bacterial, plant or animal cells to reproduce themselves, destroying the cell in the process
  • Bacteria can feed in many different ways and live in many different habitats
  • Yeast are fungi and can reproduce rapidly of waste products are removed and they are given food and the ideal temperature and pH
  • Yeast is used in fermentation to make beer or wine. Distillation is then used to make drinks with higher alcohol concentration
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  • If biofuels are burnt at the same rate that they grow, there is no net carbon dioxide output
  • Some areas of forests are being destroyed to grow biofuels
  • Biogas does not produce as much pollution as burning diesel or petrol but does not release as much energy as natural gas
  • Biogas contains more than 50% methane, some carbon dioxide and traces of other gases
  • Biomass can be burnt and used as a fuel. Examples include : 1) fast growing trees. 2) products of fermentation such as alcohol or biogas
  • Alcohol produced by fermentation and mixed with petrol is called gasohol
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  • Soil contains : 1) differently sized mineral particles. 2) different amounts of dead material. 3) different amounts of air
  • Humus in the soil is important to life as it : 1) increases the air content. 2) decays to release minerals
  • Earthworms are important in soil because they : 1) bury dead material so that it can decay. 2) aerate the soil. 3) mix up soil layers. 4) neutralise acidic soil
  • Numbers of aquatic organisms vary during the year as light, temperature and minerals vary
  • Water can be polluted by sewage or by fertiliser run-off
  • For food, marine organisms depend on plants, dead organisms floating down or bacteria acting as producers
  • Life in water is easier than on land because organusms do not dry out, temperatures do not vary much and the water gives support
  • Water content has to be controlled and the water resists movement
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  • Enzymes can be used in biological washing powders to convert stains to soluble products that can be washed away
  • Because of the enzymes, biological washing powder has to be used at a certain temperature and pH
  • Enzymes can be immobilised in gel and used to produce lactose-free milk
  • DNA fingerprints can be made to allow organisms to be indentified from their genes
  • Sucrase (invertase) is used to convert sucrode to glucose and fructose, which is sweeter and so less needs to be used in foods
  • Various enzymes and plasmaids allow genes to be transferred to produce transgenic organisms
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