AQA GCSE Biology Biology Paper 2 (Foundation), June 2025: Question 9
10 marks · Standard Demand difficulty · Short Answer
Analyze an investigation into daisy distribution and soil water content along a transect from a tree, calculate a percentage, and evaluate abiotic factors.
Practise this questionQuestion
Question text
09 Students investigated how many daisy plants were growing in a field at different
distances from a tree.
This is the method used.
1. Place a 20-metre tape measure on the ground, with the tree at 0 metres.
2. Place a 1 m2 quadrat on the ground every 4 metres along the tape measure.
3. Count the number of daisy plants in each quadrat.
4. Take a soil sample from each quadrat to find the percentage of water in the soil.
Figure 14 shows the tree and the tape measure.
Figure 14
This is the method used for finding the percentage of water in each soil sample
(step 4):
5. Weigh an empty container.
6. Place the soil sample in the container and weigh again.
7. Heat the container of soil in an oven at 100 °C for several hours.
8. Allow the container of soil to cool and weigh again.
9. Repeat steps 7 and 8 until there is no further change in mass.
09.1 Suggest why the students repeated steps 7 and 8 until there was no further change
in mass.
*36* [1 mark]
Table 6 shows the results.
Table 6
Distance from the tree in metres
48 12 16 20
Mass of fresh soil in grams 250 266 260 248 252
Mass of dried soil in grams 225 234 209 184 181
Mass of water lost from soil in grams 25 32 51 64 71
Percentage of water in soil 10 12 20 26 X
Number of daisies per m2 0 7 15 28 32
09.2 Calculate percentage X in Table 6.
Give your answer to the nearest whole number.
[3 marks]
Percentage X (nearest whole number) = %
09.3 Describe the effect of distance from the tree on the percentage of water in the soil
between 4 metres and 16 metres.
Use Table 6.
*37* [1 mark]
09.4 A student concluded:
*38*‘As the water content of the soil increases, so does the number of daisy plants.’
Describe two changes to the investigation that would increase the validity of the
student’s conclusion.
[2 marks]
09.5 The percentage of water in the soil is an abiotic factor.
Suggest three other abiotic factors that might have caused more daisy plants to grow
further away from the tree.
Do not refer to water in your answer.
[3 marks]
Mark scheme
Show the mark scheme
Question 9
AO /
Question Answers Extra information Mark
Spec. Ref.
09.1 to remove all / the water allow to make sure there is no 1 AO3
water left 4.7.1.2
allow to make sure the soil is 4.7.2.1
(completely) dry
ignore to remove water
unqualified
AO /
Spec. Ref.
09.2 71 1 AO2
× 100 4.7.1.2
4.7.2.1
28.1(746…) 1
28 (%) allow student’s incorrectly 1
calculated percentage using
mass data for 20 metres,
rounded to nearest whole
number
AO /
Spec. Ref.
09.3 as distance increases the allow positive correlation 1 AO3
percentage of water increases allow as one increases the other 4.7.1.2
increases 4.7.2.1
allow as one decreases the RPA9
other decreases
ignore directly proportional
AO /
Spec. Ref.
09.4 any two from: 2 AO3
4.7.1.2
• repeat (at each distance) and allow repeat (at each distance) 4.7.2.1
calculate a mean and remove / identify anomalies RPA9
• test at intermediate / further
distances
• test around more / different allow test more areas
trees
• test at different angles around
the (same) tree
AO /
Spec. Ref.
09.5 any three from: 3 AO2
4.7.1.1
• light (intensity) if neither awarded allow 4.7.1.2
• temperature shade for 1 mark 4.7.2.1
RPA9
ignore sun
• type of soil
• pH (of soil) allow acidity / alkalinity (of soil)
• minerals / ions (in soil) allow salts or named examples
of ions, such as nitrate
allow fertiliser
ignore nitrogen / nutrients
• wind (intensity / direction)
• oxygen in soil
ignore (availability of) space
ignore carbon dioxide
Total Question 9 10
How to answer it
Daisy Distribution & Soil Water Transect Study
This question assesses practical ecology skills from AQA Required Practical 9 (investigating population size using transects), scientific methodology (drying to constant mass), multi-step percentage calculations, interpreting graphical/tabular trends, suggesting valid procedural improvements, and distinguishing between key abiotic factors.
Drying Soil to Constant Mass
Why repeat heating and cooling until no further change in mass? [1 mark]
✅ Correct Answer
To ensure that all of the water has been evaporated / removed (so the soil is completely dry).
🧠 Exam Technique
Always specify "all" or "completely". Saying simply "to remove water" is too vague because the first heating cycle already removed some water.
❌ Common Misconception
Do not say "to make the experiment a fair test" or "to calculate an average". Repeating until a reading stays constant is a classic technique called heating to constant mass, used strictly to ensure complete evaporation.
Percentage Calculation (Value X)
Calculate percentage X in Table 6 to the nearest whole number [3 marks]
📐 Step-by-Step Calculation
Look at column 20 metres in Table 6:
- Mass of fresh soil: 252 g
- Mass of dried soil: 181 g
- Mass of water lost: 252 − 181 = 71 g
- Step 1 (Formula & Substitution): Divide the mass of water lost by the initial fresh soil mass and multiply by 100.
Percentage = (71 ÷ 252) × 100 [1 mark] - Step 2 (Raw Calculation): Evaluate the division.
71 ÷ 252 × 100 = 28.1746...% [1 mark] - Step 3 (Rounding): Round to the nearest whole number as commanded.
Answer = 28 % [1 mark]
⚠️ Trap to Avoid
Wrong Denominator: Many students accidentally divide by the dried soil mass (71 ÷ 181 = 39.2%). Soil water percentage is always based on the total fresh sample mass (252 g).
Describing Data Trends
Describe the effect of distance from the tree on soil water % between 4 m and 16 m [1 mark]
✅ Correct Answer
As the distance from the tree increases, the percentage of water in the soil increases (positive correlation).
🧠 Exam Technique
Always state both variables clearly: "As [variable X] increases, [variable Y] increases/decreases."
❌ Examiner Warning
Do NOT say "directly proportional": At 4 m it is 10%; at 8 m it is 12% (doubling distance does NOT double the water %). Proportional has a strict mathematical definition that does not fit here.
Improving Experimental Validity
Describe two changes to the investigation to increase validity [2 marks]
✅ Any Two Valid Improvements
- Repeat transects / repeat at each distance and calculate a mean (or identify/remove anomalies).
- Place transect lines at different angles / directions around the tree.
- Repeat the investigation around other trees of the same or different species.
- Sample at smaller / intermediate intervals along the line (e.g., every 1 m or 2 m instead of every 4 m).
🧠 Top-Grade Tip: "Repeat" is never enough!
Simply writing "repeat the experiment" will score 0 marks at GCSE. You must state what you do with the repeats: repeat and calculate a mean or repeat to identify anomalies.
Abiotic Factors Affecting Growth
Suggest three other abiotic factors (do NOT refer to water) [3 marks]
✅ Any Three Accepted Factors
- Light intensity (tree canopy blocks sunlight close to the trunk)
- Temperature (shade keeps soil/air cooler)
- Mineral ions / soil nutrients (e.g. nitrates, magnesium, soil pH)
- Soil pH / acidity
- Wind intensity / direction
- Oxygen level in the soil
💡 Key Definitions
Abiotic: Non-living physical or chemical factors that affect ecosystems.
Near the tree, shade lowers both light intensity and temperature, limiting photosynthesis in small plants like daisies.
❌ Disallowed Answers (Zero Marks)
- Water: Specifically forbidden in the question prompt.
- "Sun" unqualified: Must state light intensity or temperature.
- "Nutrients" / "Nitrogen": Too vague; write minerals, mineral ions, or name specific ions like nitrates.
- "Space": Space is a concept of competition, not an abiotic factor.
- Carbon dioxide: Atmospheric CO₂ concentration does not meaningfully differ across a 20 m field.
Topics
Biology · Required Practicals · B7: Ecology · Required Practicals
Question and mark scheme from the AQA GCSE Biology examination, Biology Paper 2 (Foundation), June 2025. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.