sampling organsims

• 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 an unbiased estimate of species numbers
• 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 size quadrat is used in the practical?

  0.5 meters by 0.5 meters
• How do students select random points for quadrat placement?

  By drawing numbers from a bag
• If students counted 300 daisies across ten quadrats, what is the next step?

  Estimate the total population using a formula
• What is the formula to estimate total population size?

  Total population size = (total area / area sampled) * number counted
• What is the total area of the field if it measures 20 meters by 20 meters?

  $400 \text{ m}^2$
• What is the area sampled if each quadrat is 0.25 meters by 0.25 meters and used 10 times?

  $2.5 \text{ m}^2$
• Why is the total population estimate considered an estimate?

  Because it may not represent the entire area
• What should be done if the quadrat throws do not represent the whole area?

  Increase the number of quadrat throws
• How do you measure the effect of light intensity on daisies' 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 daisies' numbers change with distance from the tree.
• What tool can be used to measure light intensity?

  A light meter or an app
• Why might there be fewer daisies under a tree?

  Lower light intensity due to shading
• What other abiotic factor might affect the number of daisies?

  Water and mineral absorption by the tree
• What is the importance of this required practical?

  • Helps understand population estimation
  • Teaches sampling techniques
  • Investigates species distribution factors