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GCSE Biology Required Practical: Measuring Population in a Habitat

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Key Stage 4

Meaning

Estimate the size of a population of a species within a habitat using sampling techniques and investigate a factor affecting population size.

Method

Estimate the population of a species within a habitat using random sampling.

  1. Place a quadrat in a random location in a field. (Exam boards apparently do not allow throwing of the quadrat, even though this would reduce bias in the choice of sample space.)
  2. Count the number of daisies within the quadrat.
  3. Repeat steps 1 and 2 ten times.
  4. Calculate the mean number of daisies.
  5. Use the following equation to estimate the number of daisies in the field:
Estimated population = \(\tfrac{area sampled}{total area}\) x number of daisies

Investigate the effect of a factor on plant distribution using a transect.

  1. Stretch a 30m tape from the base of a tree out into an open area of field. This will be the transect.
  2. Place a quadrat at 0m on the transect and count the number of daisies within the quadrat.
  3. Repeat step 2 six times moving the quadrat 5m further along the transect each time.
  4. At each location you may measure the light intensity, soil hydration or soil pH to determine if this factor affects the abundance of daisies.

References

Edexcel

Biology core practicals; quadrats and transects, pages 128-129, GCSE Combined Science, Pearson Edexcel