RP8: plant responses

• What is the independent variable in the investigation of light intensity on seedlings?

  The light intensity
• What is the dependent variable in the investigation of light intensity on seedlings?

  The height of the seedlings
• What is a control variable in the experiment?

  The volume of water used, type of seed
• How many mustard seeds are placed in each petri dish?

  10 mustard seeds
• Why is it important to ensure the same number of seedlings in each dish?

  To maintain consistency in the experiment
• What should be done if one dish has more seedlings than the others?

  Remove seedlings from the dishes with more to match the lowest count
• What tool is used to measure the height of each seedling?

  A ruler
• Why must care be taken not to damage the seedlings while measuring?

  To ensure accurate growth measurements
• Where should one dish be placed to receive full sunlight?

  On a very bright windowsill
• What is phototropism?

  The growth of seedlings towards the light source
• How does auxin affect seedling growth in relation to light?

  Auxin concentrates on the side away from the light, causing faster growth on that side
• What happens to seedlings kept in the dark?

  They grow rapidly trying to reach the light
• Why do seedlings in the dark have small and yellow leaves?

  They cannot carry out photosynthesis without light
• How can the effects of gravity on seedlings be investigated?

  By placing a dish of seedlings on its side in the dark
• What direction do the chutes and roots grow when seedlings are placed on their side?

  Chutes grow upwards and roots grow downwards
• How does auxin affect root growth in response to gravity?

  Auxin builds up on the lower side of the root, inhibiting growth there
• What is a common question type related to this required practical?

  Questions about the effects of light and gravity on seedlings
• What should be done with the results after the experiment is finished?

  Calculate the mean seedling height and draw diagrams
• How do the results of seedlings in full sunlight compare to those in partial light?

  The height of the seedlings is similar in both conditions
• Why do plants not need full sunlight to grow effectively?

  Because chlorophyll is efficient at absorbing light energy
• Why is it important to water the seeds every day with the same volume of water?

  To ensure consistent growth conditions for the seedlings
• Why is it necessary to record results in a table?

  To organize data for analysis and comparison
• How long should the height of seedlings be measured for the experiment?

  For at least five consecutive days
• What role does chlorophyll play in plant growth?

  It efficiently absorbs light energy for photosynthesis
• What is the role of auxin in plant growth?

  It controls the growth direction of seedlings
• explain the method for the practical

  • place cotton wool in 3 petri dishes and then soak them with equal volumes of water
  • place 10 mustard seeds in each dish
  • leave dishes in a warm place to allow seeds to germinate
  • water the seeds every day with the same vol. of water
  • make sure the 3 dishes have the same number of seedlings
  • use a ruler to measure height of each seedling - make sure to hold the stems straight but dont damage it
  • put the dishes in different conditions - full sunlight, partial light, darkness