sampling organisms

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

  How to measure the population size of a common species and use sampling techniques
• What is the purpose of random sampling in estimating population size?

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

  1. Use random sampling with a quadrat.
  2. Place two tape measures at right angles, each 20 meters long.
  3. Randomly select coordinates using a bag of numbers.
  4. Count the daisies in the quadrat at those coordinates.
  5. Repeat for a total of ten samples.
  6. Use the formula:

  • Total population size = (Total area / Area sampled) * Number of organisms counted
• What is the size of the quadrat used in the practical?

  0.5 meters by 0.5 meters
• How do you calculate the total area of the field in the practical?

  The total area is calculated as $20 \text{ m} \times 20 \text{ m} =$$400 \text{ m}^2$
• If 300 daisies were counted across ten quadrats, what is the area sampled?

  The area sampled is $0.5 \text{ m} \times 0.5 \text{ m} \times 10 =$$2.5 \text{ m}^2$
• What is the estimated total population of daisies in the field?

  The estimated total population is 48,000 daisies
• Why is the population estimate considered an estimate?

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

  Increase the number of quadrat throws
• How do you investigate the effect of a factor on the distribution of a species?

  1. Identify the factor to investigate (e.g., light intensity).
  2. Use a transect line to measure changes in distribution.
  3. Place a tape measure from the factor (e.g., tree) outward.
  4. Count the number of species at intervals along the transect.
  5. Record the relevant environmental factors (e.g., light intensity).
• What tool can be used to measure light intensity?

  A light meter or an app
• Why might the number of daisies increase as you move away from a tree?

  Because light intensity is higher further from the tree
• What other abiotic factors might affect the number of daisies besides light intensity?

  Water and minerals in the soil
• What is the importance of the required practical in the study of ecology?

  • Helps understand population estimation techniques
  • Teaches sampling methods
  • Provides hands-on experience with data collection
  • Enhances understanding of species distribution factors