Required Practical 9:Sampling Organisms

• What should you be able to describe by the end of the video?

  Population size measurement and sampling techniques
• What is the purpose of random sampling in estimating population size?

  To obtain a representative sample of species
• What is the procedure for estimating the total population of daisies?

  1. Use random sampling with quadrats.
  2. Place tape measures at right angles.
  3. Select random numbers to position quadrats.
  4. Count daisies in each quadrat.
  5. Use the formula to estimate total population.
• What is the size of the quadrat used in the practical?

  0.5 meters by 0.5 meters
• How do students select random positions for the quadrats?

  By drawing numbers from a bag
• What is the total area of the field being sampled?

  $400 \text{ m}^2$
• How do you calculate the area sampled using quadrats?

  Multiply quadrat area by number of samples
• What was the total number of daisies counted in the samples?

  300 daisies
• What is the formula for estimating total population size?

  Total population = (total area / area sampled) * organisms counted
• What does the estimate of 48,000 daisies indicate?

  It is an estimate based on sampling
• Why might the quadrat throws not represent the whole area?

  Regions may have varying daisy densities
• How do you measure the effect of light intensity on daisy distribution?

  1. Use a transect line from the tree.
  2. Count daisies at intervals along the line.
  3. Record light intensity using a light meter.
  4. Analyze how daisy numbers change with distance from the tree.
• What tool can be used to measure light intensity?

  A light meter or an app
• Why might more daisies be found further from the tree?

  Lower light intensity under the tree
• What other abiotic factor might affect daisy numbers besides light intensity?

  Water and minerals absorption by the tree
• What are the key components of the required practical for measuring species distribution?

  • Random sampling with quadrats
  • Use of tape measures
  • Counting organisms
  • Recording environmental factors
  • Analyzing data for patterns