sampling organisms practical

• 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 distribution
• 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 points using a bag of numbers.
  4. Count daisies in each quadrat.
  5. Repeat for a total of ten samples.
  6. 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 you calculate the total area of the field?

  Multiply 20 meters by 20 meters
• If the total area is 400 square meters, what is the area sampled with one quadrat?

  1. 5 square meters
• What is the formula for estimating the total population size?

  Total population size = (total area / area sampled) * number counted
• What was the estimated total population of daisies in the example?

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

  Sampling may not represent the whole area
• What should you do if you suspect uneven distribution of daisies?

  Increase the number of quadrat throws
• 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 or app.
  4. Analyze how daisies change with distance from the tree.
• What abiotic factor is primarily being measured in the study?

  Light intensity
• Why might the number of daisies increase as you move away from the tree?

  Lower light intensity under the tree
• What other factor might affect the number of daisies besides light intensity?

  Water and minerals absorption by the tree
• What is the importance of the required practical in the study of species distribution?

  • Helps understand population estimation
  • Teaches sampling techniques
  • Investigates environmental effects on species