June 2009 higher mark questions

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Describe how the concentration of a reducing sugar

  • Usind standard/ known concentration of reducing sugar 
  • Heat with Benedict's solution 
  • Use the same volume of solutions each time
  • Use of excess Benedict's 
  • Changes from blue to green to yellow/orange to orange-red
  • Remove precipitate - centrifuging and decanting
  • Calibrate colorimeter using blank unreacted Benedict's using a red filter (because this is the colour of the desired final product)
  • Reading of either transmission or absorption 
  • More transmission = more reducing sugar present
  • Plotting transmission against reducing sugar concentration 
  • Reading of unknown sugar - read off graph to find concentration 
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Smoking could cause changes in alveoli

  • Tar destroys cilia
  • Tar results in overactive goblet cells - accumulation of mucus leads to infections/ bronchitis
  • Neutrophils/ macrophages/ phagocytes/ monocytes invade
  • Secrete elastase 
  • Elastic fibres destroyed
  • Lower level of elastase inhibitor
  • Alveoli fail to recoil 
  • Constriction of terminal bronchioles so coughing causes alveoli to burst 
  • Reducing surface area
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B lymphocytes in the immune response

  • Humoral response
  • B lymphocytes carry antibodies on cell surface membrane
  • These antobodies are complementary to only one antigen
  • Clonal selection
  • Activation of specific B lymphocyte by macrophages (T helper cells)
  • Clonal expansion 
  • Selected cell divides by mitosis - clones
  • B cells differentiate
  • B cells form plasma cells - secrete antibodies that are complementary to antigen
  • B cells form memory cells - provide immunological memory 
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