PRACTICAL 6 MARKERS

• investigating enzymes (pH)

  1. Put starch and amylase into boiling tubes and in water bath at 20°C
  2. Mix starch + amylase + iodine solution
  3. Pipette mixture to spotting tile every 10 seconds
  4. Record time from colour changes (from blue-black to brown,
  5. Repeat and get average time
  6. Repeat with different temperatures and record time
  7. Keep volume, concentration and pH constant (control variables)
• Osmosis practical

  1. Cut out and record mass of several potato cylinders using balance
  2. Prepare sucrose solutions with different concentrations
  3. Place potato cylinders into sucrose solutions
  4. Remove cylinders, pat dry and record final mass
  5. Calculate %change for each cylinder
  6. Repeat (1-5)and calculate average %change for each sucrose conc.
  7. Plot %change (x-axis) against sucrose concentration (y-axis)
  8. Draw line of best fit and find concentration where %change = 0
• Investigating enzymes (temperature)

  1. Put starch and amylase into boiling tubes and in water bath at 20°C
  2. Mix starch + amylase + iodine solution + buffer solution of first pH
  3. Pipette mixture to spotting tile every 10 seconds
  4. Record time from colour changes (from blue-black to brown)
  5. Repeat and get average time
  6. Repeat with different buffer solutions and record time
  7. Keep volume, concentration and temperature constant