AQA GCSE Biology Biology Paper 2 (Foundation), June 2023: Question 2

8 marks · Low Demand difficulty · Short Answer

Describe the sampling method using quadrats to estimate plant population on a lawn, explain the calculations involved, and identify abiotic factors affecting plant growth.

Practise this question

Question

Question 02 illustrates a 15 m by 10 m lawn containing clumps of buttercup plants (Figure 2). The four-step sampling method using a 1 m by 1 m frame is outlined. Sub-questions 02.1 through 02.3 ask students to complete sentences using word banks regarding equipment and calculation terms, and choose how to place quadrats. Table 1 shows sample numbers 1 to 5 with buttercup counts of 2, 7, 0, 0, and 1. Sub-questions 02.4 to 02.6 ask how the population of 300 was calculated, how to improve accuracy, and to name another abiotic factor affecting buttercups.
Question text

02 Students estimated the population of buttercup plants growing on a lawn.

The lawn is a rectangle measuring 15 m × 10 m.

Figure 2 shows the lawn.

Figure 2

This is the method used.

1. Measure the length and width of the lawn.

2. Choose five locations to sample.

3. Place a 1 m × 1 m square frame at each location.

4. Record the number of buttercup plants in each square frame.

02.1 Complete the sentences.

Choose answers from the box.

[2 marks]

15 cm ruler 30 m tape measure

balance quadrat transect

The length and width of the lawn should be measured

using a .

The 1 m × 1 m square frame is called a .

02.2 How should the students choose the five locations to sample?

[1 mark]

Tick ( ) one box.

Choose locations at random.

Choose locations at the corners of the lawn.

Choose locations with lots of buttercup plants.

Choose locations with no buttercup plants.10

Table 1 shows the results.

Table 1

Sample number Number of buttercup plants

The students used their results to calculate the population of buttercup plants.

02.3 Complete the sentences.

Choose answers from the box.

[2 marks]

area mean median perimeter volume

Multiply the length of the lawn by the width of the lawn to give the

lawn’s .

Add up the total number of buttercup plants and divide by 5 to give

the 11.

02.4 The students calculated that the population of buttercup plants on the lawn was 300.

How did the students use the results in Table 1 to calculate the population?

[1 mark]

02.5 How could the students improve the accuracy of the estimate?

[1 mark]

Tick ( ) one box.

Count and record more samples.

Select locations in the middle of the lawn.

Use a square frame measuring 0.5 m × 0.5 m.

02.6 One abiotic factor that affects the number of buttercup plants on the lawn is soil pH.

Give one other abiotic factor that could affect the number of buttercup plants on

the lawn.

Do not refer to soil pH in your answer.

[1 mark]

Mark scheme

Show the mark scheme Mark scheme for Question 2 lists the answers: 02.1 requires '30 m tape measure' then 'quadrat' (2 marks); 02.2 requires 'choose locations at random' (1 mark); 02.3 requires 'area' then 'mean' (2 marks); 02.4 accepts 'multiply mean by area' or numerical equivalents like 'multiply 2 by 150' (1 mark); 02.5 requires 'count and record more samples' (1 mark); 02.6 accepts water/moisture, light, temperature, oxygen in soil, wind, or minerals/ions (1 mark). Total 8 marks.

Question 2

AO /

Question Answers Extra information Mark

Spec Ref.

02.1 must be in this order AO1

4.7.2.1

(30 m) tape measure 1 RPA9

quadrat

AO /

Spec Ref.

02.2 choose locations at random 1 AO1

4.7.2.1

RPA9

AO /

Spec Ref.

02.3 must be in this order AO1

4.7.2.1

area 1 RPA9

mean

AO /

Spec Ref.

02.4 multiply mean by area allow multiply 2 by 150 1 AO1

4.7.2.1

allow multiply total (of five RPA9

quadrats) by a fifth of the area

allow multiply 10 by 30

AO /

Spec Ref.

02.5 count and record more samples 1 AO3

4.7.2.1

RPA9

AO /

Spec Ref.

02.6 any one from: 1 AO2

• water / moisture allow humidity 4.7.1.2

allow rain

allow drought

• light ignore sun unqualified 9

allow shade (by eg building)

• temperature

• oxygen in the soil ignore oxygen unqualified

• wind

• minerals / ions allow named ions

allow fertiliser / salts

ignore carbon dioxide

ignore nutrients

ignore (soil) pH

Total Question 2 8

How to answer it

Estimating Plant Population Using Quadrats (RPA 7)

📋 What this question tests

This question assesses fundamental knowledge from AQA GCSE Biology Topic 4.7 (Ecology) and Required Practical 7:

  • Selecting appropriate field equipment (quadrats and tape measures).
  • Understanding why random sampling prevents bias.
  • Calculating total field area, mean counts per quadrat, and estimated population size.
  • Knowing how to improve the accuracy and reliability of field survey estimates.
  • Recalling non-living (abiotic) environmental factors that affect plant distribution.
Question 02.1

Field Equipment Identification

Sentence Completion (2 Marks)

✅ Correct Answers

1. 30 m tape measure (1 mark)

2. quadrat (1 mark)

Must be in this exact order to match the text prompts.

💡 Key Knowledge

  • A tape measure establishes grid coordinates over large distances (here the lawn is 15 m × 10 m). A 15 cm ruler is far too short.
  • A quadrat is a square frame (usually 0.5 m × 0.5 m or 1 m × 1 m) placed on the ground to sample organisms.
  • A transect is a line across a habitat, not a square frame.
Question 02.2

Sampling Strategy

Multiple Choice (1 Mark)

✅ Correct Answer

☑ Choose locations at random. (1 mark)

🧠 Exam Technique: Avoiding Bias

Whenever you are estimating total population across an entire area, samples must be chosen at random (e.g. using a random number generator for x and y coordinates).

❌ Common Misconceptions

  • "Choose locations with lots of buttercups": This introduces deliberate bias and leads to a massive overestimation.
  • "Choose locations at the corners": Non-random and unrepresentative of the middle of the field.
Question 02.3

Mathematical Terms in Ecology

Sentence Completion (2 Marks)

✅ Correct Answers

1. ...give the lawn's area. (1 mark)

2. ...divide by 5 to give the mean. (1 mark)

💡 Key Knowledge

  • Length × Width = Area (measured in m²).
  • Sum of counts ÷ Number of samples = Mean (the average number of plants per quadrat).
Question 02.4

Population Calculation Explanation

Extended Response (1 Mark)

✅ Acceptable Answers (Any 1)

  • Multiply the mean by the area
  • Multiply 2 by 150
  • Multiply total plants (10) by a fifth of the area (30)

📐 Step-by-Step Calculation Breakdown

Step 1: Lawn area
15 m × 10 m = 150 m²

Step 2: Total buttercups sampled
2 + 7 + 0 + 0 + 1 = 10 buttercups

Step 3: Mean per quadrat (1 m²)
10 ÷ 5 = 2 buttercups per m²

Step 4: Estimated total population
Mean × Total Area = 2 × 150 = 300 buttercups

Question 02.5

Improving Investigation Accuracy

Multiple Choice (1 Mark)

✅ Correct Answer

☑ Count and record more samples. (1 mark)

🧠 Exam Technique

Five quadrats cover only 5 m² out of a 150 m² lawn (just 3.3% of the total area). Taking more samples makes the mean far more representative, reduces the effect of anomalies, and improves estimate accuracy.

❌ Common Errors

  • "Use a frame measuring 0.5 m × 0.5 m": A smaller quadrat samples less area, which does not improve accuracy.
  • "Select locations in the middle": Ignoring edges removes randomness and causes sampling bias.
Question 02.6

Abiotic Factors Affecting Plants

Recall (1 Mark)

✅ Acceptable Answers (Name any ONE)

  • Water / moisture (allow: rainfall, drought, humidity)
  • Light intensity (allow: shading by trees/buildings)
  • Temperature
  • Mineral ions / minerals (allow: nitrates, fertiliser, salts)
  • Oxygen level in soil
  • Wind intensity / direction

❌ Common Pitfalls & Ignored Terms

  • Soil pH: Explicitly forbidden by the prompt ("Do not refer to soil pH").
  • "Sun" alone: Too vague. Must state light intensity or sunlight.
  • "Oxygen" alone: Terrestrial plants get atmospheric O₂ easily; must specify oxygen in the soil.
  • "Nutrients" alone: Too broad; specify minerals or named ions like nitrates.
  • Biotic factors: Answers like herbivores, competition, trampling, or disease get 0 marks because they are living factors.

Topics

Biology · Required Practicals · B7: Ecology · Required Practicals

Question and mark scheme from the AQA GCSE Biology examination, Biology Paper 2 (Foundation), June 2023. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.