cpac

• plant mineral deficiencies - topic 4

  AIM: investigate effect of mineral deficiencies on plant growth

  IV: minerals present

  DV: physical characteristics of the plant

  Controlled Variable:

  • volume of mineral sol used
  • same species of plant
  • size of plant
  • amount of light received
  • same amount of time growing

  METHOD:

  1. half fill test tubes with solution
  2. cover top with clingfilm, poke hole, place plant in hole making sure roots are in soln
  3. wrap all tubes in foil and place in test tube rack, leave on sunny window sill
  4. leave for week, come back to measure, write down observations and compare
• habituation - topic 8

  AIM: to investigate habituation to a stimulus in snails

  IV: number of pokes with cotton bud

  DV: time taken for eye stalks to remerge from shell

  Controlled Variables:

  • age and size
  • handling history - all from same habitat
  • point where bud touches - between eye stalks

  METHOD:

  1. get snail and allow to acclimatise
  2. dampen cotton bud and start stopwatch
  3. measure length of time between touch and snail being out of shell
  4. repeat and record
• temp on cell membranes - topic 2

  IV: temp of water bath

  DV: % transmission of light through solution

  Controlled Variables:

  • volume of water - 10cm3
  • time left in water
  • size of beet
  • same colourimeter used
  • volume of beet sol - 2cm3 should be added to each curvette

  METHOD:

  1. cut beet and place in water to remove betalain when cut then wash and dry
  2. fill tubes with water and place in diff water baths
  3. once at temp place beet piece in each tube
  4. set colourimeter to blue/green filter and calibrate by using water first
  5. use colorimeter to measure transmission
• vitamin c - topic 1

  IV: type of fruit juice

  DV: volume of juice needed to decolourise 1cm3 of DCPIP

  Controlled Variables:

  • temp
  • conc of DCPIP - 1% sol
  • vol of DCPIP - 1cm3
  • same end point colour

  METHOD:

  1. pipette 1cm3 of 1% blue DCPIP into conical flask
  2. fill burette with juice take note of initial value
  3. titrate white swirling flask
  4. stop when DCPIP changes colour
  5. work out volume used and repeat
• caffeine on daphnia heart rate - topic 1

  IV: caffeine conc

  DV: heart rate

  Controlled Variables:

  • temp
  • vol of solns
  • size of daphnia
  • time to acclimatise

  METHOD:

  1. place daphnia on cavity slide and dab around to remove pond water then add drops of caffeine solns
  2. leave daphnia to acclimatise for 5 mins
  3. count heart rate using clicker then repeat for other daphnia then diff concs
• changing enzyme conc on rate of reaction- topic 2

  IV: protease concentration

  DV: time taken for enzyme to breakdown substrate

  Controlled Variables:

  • temp
  • volume of enzyme soln
  • volume of substrate
  • conc of substrate

  METHOD:

  1. set up water bath
  2. mark x on one side of test tube and fill with vol of casein sol and place in water bath
  3. place a second tube containing conc of trypsin and let both acclimatise for 3 mins
  4. add trypsin to casein and start stopwatch. time how t]long for casein to turn transparent - when u can see x
  5. repeat then with other conc of trypsin
• observing mitosis - topic 3

  method:

  1. place test tube of HCl into water bath at 60
  2. cut of garlic root tip and put in watch glass containing vol of acetic alcohol for 12 mins
  3. remove tip then place into another watch glass with ice cold water then dry
  4. place tips in the hot HCl. transfer to slide and macerate with mounted needle
  5. add toluidine blue to root tip, add coverslip and blot
  6. view under microscope
• looking at plant stems - topic 4

  method:

  1. place small piece of rhubarb and place on watch glass. use forceps to pick out vascular bindles and pry them apart. add methylene blue and leave for 5
  2. dap off extra stain with filter paper. drop of glycerol onto fibres and add cover slip
  3. look under microscope
• strength of fibres - topic 4

  IV: type of fibre used

  DV: amount of mass that can be added before fibre snaps

  Controlled Variables:

  • length of fibre
  • same mass of weights should be used

  METHOD

  1. remove plant fibres using retting and connect between two clamps
  2. gradually add mass (hanging masses) in the same interval to the middle until fibre snaps
  3. repeat but with fibres from different plants
  4. calculate tensile strength by force/cross sectional area
• measuring the rate of oxygen uptake- topic 7

  Controlled Variables:

  • mass of organisms
  • temp
  • time

  METHOD:

  1. place 5g of maggots into tube and add drop of dye
  2. open three way tap and move fluid to a convenient place
  3. mark starting position and close three way tap and start stop watch
  4. mark position of fluid every one minute for 5 minutes
  5. open three way tap and measure distance travelled by liquid during each min
  6. record results in table
• gel electrophoresis - topic 8

  method:

  1. mix dna sample with restriction enzyme and dye
  2. prepare agar and pour into electrophoresis
  3. once set, fill with buffer soln
  4. use micropipette to fill wells
  5. connect tank to electrical supply and turn it on. leave it until the dye has moved to opposite side of tank
  6. turn of supply and remove gel from tank. view samples under UV
• effect of temp on brine shrimp hatching

  IV: temp of each sample

  DV: number of hatched shrimps

  Controlled Variables

  • amount of salt used
  • volume of water used
  • number of brine shrimp eggs
  • light intensity
  • time

  METHOD:

  1. set up water baths at diff temps
  2. place 2g of sea salt in 100cm3 of de-chlorinated water and stir
  3. place eggs onto a sheet of paper, wet another sheet and use to pick up eggs. place wet sheet into beaker egg side down.
  4. after a few mins use forceps to remove paper making sure all eggs are in water
  5. incubate at diff temperatures. next day count how many hatched