bacteria

• Describe aseptic techniques that should be used when working safely with bacteria 

  -       Keep lid open for as little time as possible 

  -       Working in updraught of flame- bunsen burner creates convection current 

  -       Flaming/disinfecting equipment 

  -       Disinfect the bench before and after working 
• Explain why some bacteria grow rapidly in skin wounds (3) 

  -       Warm temp increasing rate of reaction in bacteria/optimum enzyme energy

  -       Availability of water for bacterial cell functions 

  -       Oxygen available for aerobic respiration, if not available can respire anaerobically
• Devise a procedure that scientists may have used to measure the effects of these extracts on pathogenic bacteria (4)

  • production of agar plates with bacteria- plates are inoculated/seeded with bacteria 
  • soak filter paper discs with plant extract and add discs to plate 

  extracts used separately and in combination 

  • incubate for 37 degrees for 24 hours
  • measure and compare sizes of inhibition (total area- area of disc)
•  

  Explain why the agar plate was incubated at 25 degrees

  -       Allows temperature for bacteria to multiply 

  -       Without encouraging pathogenic organisms
•  

  Explain why bacteria can multiply in the blood stream when they enter the body (3) 

  -       Warm conditions/water available

  -       Suitable temp and ph. for bacterial enzymes 

  -       Glucose for respiration/energy 

  -       Amino acids used for growth