Required Practical 9: Sampling Organisms

• What is the purpose of random sampling in estimating population size?

  To obtain an unbiased estimate of species population
• What is the procedure for estimating the total population of daisies in a field?

  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
• What is the equation to estimate the total population size?

  Total population size = (total area / area sampled) * number counted
• What is the total area of the field if it is 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 there are ten quadrats?

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

  Sampling may not represent the whole area
• How do you measure the effect of light intensity on the distribution of daisies?

  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 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 affects photosynthesis
• What other abiotic factor might affect the number of daisies besides light intensity?

  Water and minerals absorption by the tree
• What is the importance of increasing the number of quadrat throws?

  • Covers a greater percentage of the area
  • Provides a more accurate estimate of population