Required Practical 8 - Plant Responses

• The effect of light intensity on the height of seedlings

  1. Place cotton wool in 3 petri dishes and soak them with equal volumes of water with 10 seeds each
  2. Leave the seeds in a warm place and allow the seeds to germinate - water every day
  3. After a few days the seeds will germinate, and now make sure the 3 dishes have the same number of seedlings
  4. Hold stems straight and measure height with ruler, then place each in different light conditions
  5. Record the height of each seedling every day for at least 5 days. Calculate the mean seedling heights for each day, and draw diagrams
• Independent variable


  Light intensity
• Dependent variable


  Height of the seedlings
• Control variable


  • Volume of water used to water seeds
  • Type of seed
  • Number of seedlings per petri dish
• Effect of gravity on seedlings

  1. A dish of seedlings is placed on its side in the dark
• Results of effect of gravity experiment

  • Shoots grow upwards
  • Roots grow downwards