PHOTO & GRAVITROPISM

• AIM:

  Investigate the effects of light or gravity on the growth of newly germinated seedlings.

  Germination is the beginning of plant growth, and the plant will continue to grow if the correct conditions are available.
• VARIABLES:

  • Independent variables: light and dark conditions (could be- colours of light, intensity of light, or the direction light comes from)
  • Dependent variable: mean height of seedlings.
  • Control variables: the number of seeds on each dish, how much they are spread out, the volume of water the seedlings are given, the temperature they are kept at.
• METHOD:

  1. Put cotton wool into three petri dishes, and add the same volume of water to each dish.
  2. Add ten seeds to each dish and place them in a warm place.
  3. Allow the seeds to germinate.
  4. Once the seeds have germinated, ensure the dishes contain the same number of seeds.
  5. One petri dish in full light on a windowsill, one in a dark cupboard, and one in partial light.
  6. Every day for one week, measure the height of each seedling and record
  7. Calculate the mean of the seedlings each day, and compare the mean heights in the three different locations.