gcse science biology unit B6 PART 2

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  • Created by: charlie
  • Created on: 27-05-13 10:46
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  • B6
    • life in water
      • adv.
        • no dehydration
        • less temp. variation
        • provides skeletal support (jellyfish)
        • waste disposal easily dispersed
      • disad.
        • more resistant than air
          • more energy needed
        • control water in body
          • diff. waters have diff. solute content
            • osmosis
              • salt water
                • shrivel and die
              • fresh water
                • swell and burst
      • amoebas
        • regulate water content
          • use contractile vacuoles
            • collects water  that diffuses in by osmosis
            • moves to cell membrane+contracts to empty water
        • single cell organism
      • plankton live in s+f water
        • phytoplankton
          • plants
        • zooplankton
          • animals+feed on phyto.
        • pop. varies according to season
          • affected by:
            • temp
            • light intensity
            • minerals (nitrates)
          • winter +deep water
            • light intensity+temp. low
              • limit photo. rate
            • min. concen. hig
          • summer+near surface
            • light intensity+temp. high
              • algae bloom (phyto.)
                • zooplank. inc.- more food
            • min. concen. low
              • limit photo. rate
      • diff. food webs
        • grazing food webs
          • begin- living producer - phyto.
            • deep water
              • bacterial producer- rely on sulphur
              • other food webs
                • feed on decomposing matter falling
                  • 'marine snow'
      • causes of water pollution
        • fertilisers and sewage
          • eutrophication
            • fertiliser enter water
              • nutrients inc. algae
                • algae die
                  • bacteria feed+use up O2
                    • fish can't respire+die
          • indicator species
            • sensitive to level of O2
              • clean- stonefly nymph
              • dirty-sludgeworm
        • industrial chemicals and pesticides
          • DDT or PCB pollute water
            • not broken down in food chain
              • passed on+ inc. in concen
    • enzymes in action
      • biological washing powder
        • non-bio- chemicals break up stains
        • same chemicals+enzymes for stubborn stains
          • products of enzyme reaction are soluble- wash out
        • wash out insoluble (stubborn) stains- proteins, starch, fats
        • moderate temps- optimum for enzymes
        • correct pH
      • medical products
        • diagnosed by presence of sugar in urine
          • first- tasted sweetness
            • then- benedicts solution - heated solution changes colour- blue-orange in presence of sugar
              • now- reagent strips (enzymes +chemicals)- dipped in urine+change colour in presence of sugar
                • immobilised enzymes - measure blood glucose concen daily
      • food industry
        • low-cal. food
          • sucrose sweetens home food
          • enzyme sucrase breaks  down sucrose=glucose+fructose(sweeter)
            • use less sugar for same sweet taste
        • cheese
          • enzyme rennet clots milk in first stages
        • juice extraction
          • enzyme pectinase breaks down pectin(cell wall in apple+oranges)- causing juice released
      • immobilised enzymes
        • easier to remove
          • encapsulate in alginate beads
            • mix with enzyme alginate+drop in calcium chloride solution
        • dont contaminate product
        • used in continuous process
        • make lactose free milk
          • immobilise lactase
            • breaks down lactose=glucose+galactose
              • easily absorbed by lactose intolerant
    • genetic engineering
      • alters genetic code
        • able to transfer genes- genetic code universal
          • 4 bases
      • genetic modified organism
        • transgenic organism
          • can be cloned
      • identify wanted gene
        • remove gene from DNA
          • cut open DNA of organism that wants it
            • insert the gene
      • done using restriction enzymes
      • e.g. bacteria engineered to produce insulin
        • bacteria loop (plasmid) - vector(carries gene into another organism)
        • taken from human cell
          • ligase joins DNA strands together
    • DNA fingerprinting
      • forensic science
      • paternity tests
      • extract DNA from cell sample
        • restriction enzymes cut into unique base order
          • if DNA section has little section of bases lots of times- cut into smaller bits
            • if  only few times- cut into bigger bits
              • separated- electrophoresis
                • fragments suspended in gel+electricity passed through
                  • DNA negative charge+travels to anode
                    • smaller bits travel faster +further
                      • DNA tagged with radioactive probe
                        • placed on photographic film
                          • film dark where radioactivity is
                            • reveals fragments
                              • look at pattern of DNA fragment positions

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