B5 - auxin

• Practical control variables:

  • Number of seeds - use same number of seeds in each dish
  • Type of seed - use seeds that come from same packet
  • Temperature - keep Petri dish in stable environment
  • Water - use measuring cylinder to add same amount of water
  • Light intensity - keep distance between bulb and dish same
• method:

  1. germinate seeds in petri dish using cotton wool and water
  2. use 30 seeds per dish
  3. once seeds germinate, remove any ungerminated seedlings
  4. place one petri dish in full light on windowsill
  5. place one petri dish in sealed cardboard box
  6. place one petri dish in partially open carboard box
  7. every day for one week, measure height of each seedling using flexible tape measure
  8. calculate mean height of each seedling per day
  9. plot graph of mean height on y axis and time on x axis