Paper 1

• Microscopy

  1. Use a scalpel and tweezers to prepare a thin layer of onion skin

  2. Add a drop of iodine to stain the cells

  3. Place a cover slip on top

  4. Place the slide on the microscope stage

  5. Start with the shortest objective lens and use the coarse and fine focus knobs to bring the specimen into focus

  6. Change to a higher magnification objective lens and refocus if needed

  7. You can use a graticule (tiny ruler) to measure cell size in micrometers
• Photosynthesis

  1. Use pondweed submerged in water in an inverted test tube or measuring cylinder

  2. Cut the stem at an angle and add sodium hydrogen carbonate to the water

  3. Measure the distance between the light source and the pondweed

  4. Count the bubbles of oxygen released or measure the volume of oxygen made in a minute

  5. Repeat at different distances and plot the results against distance