Biology paper 1 practicals

• Photosynthesis-pondweed practicle

  • The rate of photosynthesis in the water plant increases as the light is moved closer to the plant which increases the light intensity this tells us that the light is acting as the limiting factor
  • when the light is moved further away from. The water plant ( pondweed) the rate of photosynthesis falls shown by a slowing down in the stream of bubbles produced
  • if the light moves closer again the stream of bubbles increases again becomes faster showing the increased rate of photosynthesis.
• Microscopy

  • peel off the epidermal layer on the onion using forceps
  • mount onto the microscope stage with a drop of water using a pipette making sure the tissue lies flat
  • add 2 drops of iodine to stain the cell
  • place the cover slip slowly to make sure the air bubbles doesn’t get trapped
  • rotate the objective lens to make the low power in line with the stage
  • turn the course focus so that the stage is close with the objective lens as possible
• Osmosis

  • use a cork porer to cut 5 potato cylinders
  • trim using a sharp knife and ruler to have them the same length
  • measure and record the mass and length of each cylinder
  • measure the equal quantities of the sugar solution and add to the boiling points then you can label them
  • add a potato cylinder to each tube
  • leave the cylinders overnight in a test tube rsck
  • remove the cylinders and lightly pat it dry
  • measure the length and mass of each cylinder and calculate the percentage
• Food test

  • take the food sample and grind it with distilled water using a mortar and pestle
  • add the paste into a beaker and more distilled water. Stir the solution
  • filter the solution to remove suspended food particles
• ( food test) starch

  test: iodine Result: orange to black
• (food test) sugar


  text: Benedicts biuret Result: blue to red
• (food test) protein 


  Text: biuret Results: blue to liac
• (Food test) lipids


  test : ethanol Result: cloudy emulsion