AQA GCSE Combined Science: Trilogy Biology Paper 2 (Higher), 2022: Question 3

7 marks · Standard Demand difficulty · Extended Answer

Identify one biotic factor affecting buttercup numbers on a school field and describe a fieldwork method using quadrats or transects to investigate whether soil water content affects the number of buttercup plants.

Practise this question

Question

The question page shows Question 03 about ecology on a school field. It states that one area of soil is usually wet and another is usually dry, and that students investigated the effect of water in the soil on the number of buttercup plants growing in each area. Part 03.1 asks for one biotic factor that may affect the number of buttercups on the field for 1 mark, and part 03.2 asks for a method to investigate whether the amount of water in the soil affects the number of buttercups in the field for 6 marks, with lined space for an extended written response.
Question text

03 On a school field:

• one area of the soil was usually wet

• another area of the soil was usually dry.

Students investigated the effect of water in the soil on the number of buttercup plants

growing in each area.

03.1 Water is an abiotic factor.

Name one biotic factor which may affect the number of buttercups growing on

the field.

[1 mark]

03.2 Describe a method to investigate if the amount of water in the soil affects the number

of buttercups in the field.

[6 marks]

Mark scheme

Show the mark scheme The mark scheme is presented in tables for Questions 03.1 and 03.2 with columns for answers, extra information, marks, and specification references. For 03.1, accepted biotic factors include competition, herbivores, trampling or mowing, pollinators, and pathogens, for 1 mark. For 03.2, up to 6 marks are awarded for a valid fieldwork method using either quadrats in wet and dry areas or a transect between them, including placing quadrats randomly or systematically, counting buttercups, using at least five samples, measuring soil moisture with suitable equipment, repeating sampling, and calculating means or estimated totals; the spec references shown are 4.7.1.3 and 4.7.2.1, plus RPA7.

AO /

Question Answers Extra information Mark

Spec. Ref.

03.1 any one from: 1 AO2

• competition allow other plants / trees 4.7.1.3

(growing in the field) RPA7

• herbivores allow named herbivore

allow pests

• trampling / mowing

• pollinators allow insects or named

pollinator

• pathogens allow infection

– OMBINED SCIENCE: TRIignore disease unqualifiedLOGY – –

AO /

Spec. Ref.

AO1

03.2 any six from: 6

4.7.2.1

allow mark out a transect in

RPA7

• mark out (grid) area in wet each of the two areas

and in dry area

allow description of a method to

• method for placing quadrat(s) place quadrat(s) randomly /

systematically

do not accept throwing quadrats

randomly

ignore percentage cover of

• count / record number of buttercups

buttercups (in the quadrat)

• use at least 5 quadrats in

each area

• take soil moisture readings

• use suitable equipment for

readings, eg soil moisture

meter allow (for each area)

• calculate the mean (in each total number of buttercups

area) divided by total area sampled,

• use the mean and area to multiplied by total area for 2

calculate total number in wet marks

area and total number in dry

area

OR

any six from (6):

• transect between wet area

and dry area allow description of a method to

• place quadrat(s) regularly place quadrat(s) systematically

along transect

• count / record number of

buttercups (in the quadrat)

• use at least 5 quadrats along

transect

• take soil moisture readings

• use suitable equipment for

readings, eg soil moisture

meter

• repeat transects

• calculate the mean at each

distance along the transects

– OMBINED SCIENCE: TRILOGY – –

Total Question 3 7

12Question 4

How to answer it

Buttercups in Wet and Dry Soil

What this question tests

This question tests your ability to: identify a biotic factor, describe a fair ecological sampling method, and use key fieldwork ideas such as quadrats, transects, repeats, means, and soil moisture readings. You need to show how to collect reliable data and compare the wet and dry areas.

Part 03.1 — Name one biotic factor

1 mark

✅ Correct answer

One biotic factor: competition

Other acceptable answers: herbivores , trampling , mowing , pollinators , pathogens .

💡 Key knowledge

  • Biotic means a living factor, or something caused by living organisms.
  • In this question, a biotic factor must affect how many buttercups can grow.
  • Examples:
    • Competition from other plants for light, water, space, or minerals
    • Herbivores eating the plants
    • Pollinators helping reproduction
    • Pathogens causing disease

🧠 Exam technique

For a 1-mark “name one” question, you only need one clear term. No explanation is needed unless the question asks for it.

The mark scheme allowed several answers, so any one correct biotic factor scores the mark.

❌ Common errors

  • Saying water — that is abiotic, so it does not score.
  • Writing a vague phrase like weather without linking it to living things.
  • Giving a whole sentence that never names a biotic factor clearly.

Part 03.2 — Describe a method to investigate the effect of water in the soil

6 marks

✅ Correct answer: what a full-mark method could include

  • Mark out a grid area in both the wet area and the dry area, or use a transect between them.
  • Place quadrats randomly or systematically in the area / along the transect.
  • Count and record the number of buttercups in each quadrat.
  • Use at least 5 quadrats in each area.
  • Take soil moisture readings with suitable equipment, such as a soil moisture meter.
  • Repeat the sampling and calculate the mean number of buttercups in each area.
  • Compare the wet and dry areas using the mean number of buttercups.

Alternative transect method: lay a transect line from the wet area to the dry area, place quadrats at regular intervals, count buttercups in each quadrat, repeat transects, and calculate the mean at each distance.

💡 Key knowledge

  • Quadrat = frame used to sample plants in a set area.
  • Transect = line used to sample how plants change across a habitat.
  • Mean = total number counted ÷ number of quadrats.
  • Fieldwork should be fair, repeatable, and reliable.
  • The investigation is about whether soil water affects buttercup number, so you must measure both the plant number and the moisture level.

🧠 Exam technique

  • To get 6 marks, include several separate steps from the mark scheme.
  • Write in a clear sequence: set up → sample → measure → repeat → calculate → compare.
  • Use scientific words like quadrat , transect , mean , and soil moisture meter .
  • Explain how you would make the results more reliable, for example by using repeats.

❌ Common errors

  • Throwing quadrats was not accepted in the mark scheme.
  • Only saying “count the buttercups” without explaining where or how often.
  • Ignoring the wet/dry comparison and not measuring soil moisture.
  • Writing percentage cover instead of counting the number of buttercups — this was ignored in the mark scheme.
  • Not repeating the sampling, so the method is less reliable.

📐 Calculations and data handling

Some answers can include simple calculations. If you do, show them clearly:

  1. Count the buttercups in each quadrat.
  2. Add the counts together for each area.
  3. Divide by the number of quadrats to find the mean.
  4. Use the mean to compare the wet and dry areas.

Example structure: total buttercups ÷ number of quadrats = mean buttercups per quadrat.

Units: counts have no units, but soil moisture readings may have units depending on the meter used.

🧠 What top-level responses did well

Students who scored well did more than just list ideas. They linked the method to the investigation by showing how to:

  • sample both habitats fairly,
  • repeat the measurements,
  • record soil moisture as the independent variable,
  • count buttercups as the dependent variable,
  • and calculate means for comparison.

❌ Calculation and method traps

  • Using only one quadrat in each area — not enough for a reliable conclusion.
  • Forgetting to state that the quadrats should be placed randomly or systematically.
  • Mixing up the independent and dependent variables.
  • Not saying what is being counted and what is being measured.
  • Giving a vague method like “look around the field” instead of a proper sampling plan.

Model 6-mark answer for 03.2

Example full answer:

Mark out a grid in the wet area and the dry area. Place quadrats randomly in each area and count the number of buttercups in each quadrat. Use at least 5 quadrats in each area. Measure the soil moisture in each area using a soil moisture meter. Repeat the sampling to make it more reliable. Calculate the mean number of buttercups in the wet area and the dry area. Compare the means to see if soil water affects the number of buttercups.

🧠 Why this gets marks

  • Marking out areas = first method point
  • Quadrats placed randomly = method point
  • Count buttercups = data collection point
  • At least 5 quadrats = reliability point
  • Soil moisture meter = linking to the factor being investigated
  • Mean and compare = analysis point

Topics

Biology · Required Practicals · B7: Ecology · Biology Required Practicals

Question and mark scheme from the AQA GCSE Combined Science: Trilogy examination, Biology Paper 2 (Higher), 2022. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.