Required Practical 8: Plant Responses (T)

• What is the purpose of the practical investigation described in the video?

  To investigate the effect of light or gravity on the growth of newly germinated seedlings.
• What are the independent and dependent variables in the investigation of light intensity on seedling height?

  • Independent variable: Light intensity
  • Dependent variable: Height of the seedlings
• What is a control variable in the experiment?

  A control variable is a factor that is kept constant, such as the volume of water and type of seed.
• Why is it important to have the same number of seedlings in each dish?

  To ensure consistency and reliability in the results.
• What steps should be taken to prepare the petri dishes for the experiment?

  1. Place cotton wool in three petri dishes.
  2. Soak the cotton wool with equal volumes of water.
  3. Place 10 mustard seeds in each dish.
  4. Leave the dishes in a warm place to allow germination.
  5. Water the seeds daily with the same volume of water.
• How should the height of each seedling be measured during the experiment?

  By using a ruler while ensuring the stems are straight.
• What conditions are the seedlings placed in during the experiment?

  • Full sunlight
  • Partial light
  • Darkness
• How long should the height of the seedlings be measured for?

  For at least five consecutive days.
• What is phototropism and how does it affect seedling growth?

  It is the growth of seedlings towards the light due to auxin concentration.
• What happens to seedlings kept in the dark during the experiment?

  • They grow rapidly trying to reach the light.
  • Their leaves become small and yellow due to lack of photosynthesis.
• What role does auxin play in the growth of seedlings?

  • Auxin concentrates on the side of the seedling away from light.
  • It causes that side to grow faster, resulting in phototropism.
  • In roots, auxin inhibits growth on the lower side, allowing upward growth.
• How does gravity affect the growth direction of seedlings?

  Roots grow downwards and shoots grow upwards due to gravity.