Cell Biology (Required Practicals)

• Use a Light Microscope to Look At Your Slide


  1. Clip the slide you've prepared onto the stage.
  2. Select the lowest-powered objective lens.
  3. Use the coarse adjustment knob to move the stage up to just below the objective lens.
  4. Look down the eyepiece. Use the coarse adjustment knob to move the stage downwards until the image is roughly in focus.
  5. Adjust the focus with the fine adjustment knob, until you get a clear image of what's on the slide.
  6. If you need to see the slide with greater magnification, swap to a higher-powered objective lens and refocus.
• Investigate the Effect of Antibiotics on Bacterial Growth


  1. Place paper discs soaked in different types of antibiotics on an agar plate that has an even covering of bacteria.
• Investigate the Effect of Antibiotics on Bacterial Growth


  2. The antibiotic should diffuse into the agar jelly. Antibiotic-resistant bacteria will continue to grow on the agar around the paper discs, but non-resistant strains will die. A clear area will be left where the bacteria have died - this is called an inhibition zone.
• Investigate the Effect of Antibiotics on Bacterial Growth


  3. Make sure you use a control. This is a paper disc that has not been soaked in an antibiotic. Instead, soak it in sterile water. You can then be sure that any difference between the growth of the bacteria around the control disc and around one of the antibiotic discs is due to the effect of the antibiotic alone.
• Investigate the Effect of Antibiotics on Bacterial Growth


  4. Leave the plate for 48 hours at 25 degree Celsius.

  5. The more effective the antibiotic is against the bacteria, the larger the inhibition zone will be.
• Investigate the Effect of Sugar Solutions on Plant Tissue

  Dependent variable - chip mass

  Independent variable - concentration of the sugar solution

  Control variable - volume of solution, temperature, time
• Investigate the Effect of Sugar Solutions on Plant Tissue


  1. Cut up a potato into identical cylinders, and get some beakers with different sugar solutions (one pure water, one very concentrated)
  2. You measure the mass of the cylinders, then leave one cylinder in each beaker for twenty four hours or so.
• Investigate the Effect of Sugar Solutions on Plant Tissue


  3. Then take them out, dry them with a paper towel and measure their masses again.

  4. If the cylinders have drawn in water by osmosis, they'll have increased in mass. If water has been drawn out, they'll have decreased in mass. You can calculate the percentage change in mass and plot a graph.