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IGCSEBiology
Trial Class

Original practice · 5 questions · 16 marks · about 18 minutes

Population and Sampling Practice Questions

Biology editorial review is supported by the named review panel. Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.

These questions test your ability to use sampling techniques and understand the factors that affect population sizes in ecosystems.

Before you open the answers

  • Attempt every question without notes.
  • Show working for calculations and write complete biological statements.
  • Use the suggested time as a guide, not a strict limit on the first attempt.

These are original practice questions. They do not reproduce an official Cambridge paper or official mark scheme.

  1. Question 1

    Paper 5/6 Both 4 marks Difficulty 3/5

    Describe how you would use quadrats to estimate the population of daisies in a field.

    Show model answer and marking guidance
    1. Place quadrats randomly across the field (use random coordinates to avoid bias).
    2. Count the number of daisies in each quadrat.
    3. Calculate the mean number of daisies per quadrat.
    4. Multiply the mean by the total number of quadrats that would fit in the entire field to estimate total population.

  2. Question 2

    Paper 4 Both 3 marks Difficulty 3/5

    State three factors that affect the size of a population.

    Show model answer and marking guidance
    1. Food availability: more food supports a larger population.
    2. Predation: more predators reduce the prey population.
    3. Disease: outbreaks can reduce population size.

  3. Question 3

    Paper 4 Extended 3 marks Difficulty 4/5

    Explain why it is important to place quadrats randomly when sampling a population.

    Show model answer and marking guidance
    1. Random placement avoids sampling bias: prevents the investigator from choosing areas that look "better".
    2. Gives a representative sample of the whole area.
    3. Makes the results more reliable and valid for estimating the total population.

  4. Question 4

    Paper 5/6 Both 3 marks Difficulty 3/5

    A student counts 12 daisies in a 0.5 m × 0.5 m quadrat. The total field area is 200 m². Estimate the total daisy population.

    Show model answer and marking guidance
    1. Area of one quadrat = 0.5 × 0.5 = 0.25 m².
    2. Number of quadrats in 200 m² = 200 ÷ 0.25 = 800.
    3. Estimated population = 12 × 800 = 9600 daisies.

  5. Question 5

    Paper 4 Extended 3 marks Difficulty 3/5

    Explain the relationship between predator and prey populations using the idea of "boom and bust" cycles.

    Show model answer and marking guidance
    1. When prey is abundant, predator population increases (more food available).
    2. As predator numbers rise, prey numbers decline (more are eaten).
    3. With less prey, predator numbers decline: prey then recovers, and the cycle repeats.

Mark the set consistently

Award a point only when the idea is clearly present in the written answer. Correct any missed point in a complete sentence, then test the same skill on a different question several days later.

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