required practicals

• how to use an optical light microscope to look at cells on a prepared microscope slide

  -place slide on to the stage

  -select the lowest power objective lens

  -turn the course focusing dial until lens almost touching the slide

  -look down on the eye piece and turn the coarse focusing dial until the cells come into focus

  -select a higher power objective lens

  -use the fine focusing dial to get cells in a clear focus
• Describe how you could investigate the effect of antibiotics on bacterial growth using zones of inhibition

  -Divide agar plate with bacteria into three parts

  -Use forceps to place filter paper disc with antiseptic in each zone

  -loosely tape lid onto agar plate to allow oxygen to reach bacteria

  -incubate at 25 degrees for 48 hours

  -measure the diameter of clear zones using a ruler from two opposite directions

  -calculate area of clear zones using Pi rsquared
• Describe how you would carry out an investigation into osmosis using potato tissue.

  -Cut identical potato cylinders using a cork borer

  -Measure and record the length and mass of cylinder using a ruler and balance

  -Add each cylinder to one of three solutions:1M sugar solution,0.5M sugar solution and distilled water

  -leave cyclinders in tubes overnight

  -remove cylinders from tubes and dry them using paper towels

  -record length and mass of each cylinder

  -draw graph of change in mass in grams (y axis) against conc of solution in mol dm-3 (x axis)
• describe how you would prepare a sample of food to be tested

  grind up food samples using pestle and mortar

  mix with water

  filter with funnel and filter paper
• Describe how you would test for the presence of a reducing sugar in a sample


  -add benedict's reagent to sample

  -heat the test tube in a hot water bath

  -if reducing sugar is present, a brick red precipitate forms. If not,the solution remains blue
• Effect of PH on Amylase experiment investigation

  -Place on drop of iodine solution into each well of the spotting tile-3 test tubes of 2cm3 of starch,amylase,buffer solution-all 3 test tubes in a water bath at 30 degrees for 10 mins

  -combine these solutions into one test tube and mix using a stirring rod-return this to the water bath and start a stopwatch-every 30s use the stirring rod to transfer one drop of the solution into a different well in the spotting tile until the iodine remains orange when drop of solution is added-repeat the above several times using different PH buffers
• Describe how you would prepare a microscope slide using onion tissue


  -Peel off epidermal layer using forceps

  -place sample on drop of water on microscope slide

  -add drops of iodine solution to sample

  -lower cover slip onto sample using forceps