AQA GCSE Biology Biology Paper 2 (Foundation), June 2022: Question 3

9 marks · Low Demand difficulty · Short Answer

Identify responses and experimental design variables in an investigation on plant tropisms and seedling growth.

Practise this question

Question

Question 3 consists of seven parts about plant tropisms. Part 03.1 asks to identify the term for plant shoot response to light from choices Adaptation, Homeostasis, and Tropism. Figure 5 shows Experiment 1 with a seedling exposed to light from the left, and Experiment 2 enclosed in a light-proof cardboard box. Part 03.2 asks students to match each experiment to drawings of seedling growth outcomes. Part 03.3 asks why Experiment 2 was set up. Part 03.4 asks how to set up a third experiment to improve validity. Part 03.5 asks for a suitable control variable from three options. Part 03.6 asks for one stimulus a plant root responds to other than light. Part 03.7 asks for two reasons why scientists repeat investigations.
Question text

03 A plant shoot responds to the stimulus of light shining on it from one side.

03.1 What name is given to the type of response shown by the plant shoot?

[1 mark]

Tick ( ) one box.

Adaptation

Homeostasis

Tropism

A student investigated the effect of one-sided light on the growth of plant seedlings.

Figure 5 shows how the student set up the investigation.

Figure 5

03.2 Draw one line from each experiment to what the seedling would look like

after 12 hours.

[2 marks]

03.3 Why did the student set up experiment 2 in this investigation?

[1 mark]

03.4 The student wanted to make the investigation of the effect of one-sided light

more valid.

*11* The student decided to set up a third experiment.

How should the student set up the third experiment?

[1 mark]

Tick ( ) one box.

Give no water to the third seedling.

Shine light from all sides on the third seedling.

Turn the third seedling so it is upside-down.

03.5 What is a suitable control variable for the investigation?

[1 mark]

Tick ( ) one box.

Keep each seedling at the same temperature.

Keep each seedling the same height above the floor.

Use the same size cardboard box for each seedling.

03.6 Give one stimulus a plant root responds to.

Do not refer to light in your answer.

[1 mark]

03.7 Scientists often repeat investigations several times.

Give two reasons why.

[2 marks]

Mark scheme

Show the mark scheme Mark scheme for Question 3 with 9 total marks. 03.1: tropism (1 mark). 03.2: line from 1 to the top seedling (curved towards the left) and line from 2 to the bottom seedling (straight and taller) (2 marks). 03.3: to act as a control or show the response is caused by light (1 mark). 03.4: shine light from all sides on the third seedling (1 mark). 03.5: keep each seedling at the same temperature (1 mark). 03.6: gravity, water, or chemicals/minerals/ions (1 mark). 03.7: any two from: to identify/eliminate anomalies or account for variation, and to calculate a mean/average (2 marks).

Question 3

AO /

Question Answers Extra information Mark

Spec. Ref.

03.1 tropism 1 AO1

4.5.4.1

AO /

Spec. Ref.

03.2 AO3

4.5.4.1

RPA8

do not accept more than one line from a box on the left

AO /

Spec. Ref.

03.3 to show the response in allow to compare with 1 AO3

experiment 1 is caused by experiment 1 4.5.4.1

(1-sided) light allow to show the difference RPA8

between (1-sided) light and no

or light

as a control do not accept control variable

AO /

Spec. Ref.

03.4 shine light from all sides on the 1 AO3

third seedling 4.5.4.1

RPA8

AO /

Spec. Ref.

03.5 keep each seedling at the same 1 AO3

temperature 4.5.4.1

RPA8

AO /

Spec. Ref.

03.6 any one from: 1 AO1

• gravity 4.5.4.1

• water allow moisture

• chemicals / minerals / ions allow a named chemical such as

nitrate

ignore nutrients

ignore light

AO /

Spec. Ref.

03.7 because of variation (in results) allow example such as some 1 AO2

or may not grow 4.5.4.1

to identify / eliminate anomalies

to calculate a mean allow to calculate an average 1

or

a mean value would be more

representative / typical

ignore to improve accuracy /

precision / validity

Total Question 3 9

How to answer it

Plant Tropisms & Seedling Investigation

📌 What this question tests

This question assesses your understanding of plant growth responses (tropisms) and the practical design principles of Required Practical 8 (RPA 8). You need to identify plant responses to directional stimuli, predict growth outcomes in controlled environments, understand experimental controls versus control variables, and explain why scientific investigations require repeats.

Part 03.1: Identifying the Plant Response

[1 Mark] • AO1 Recall

✅ Correct Answer

Tick: Tropism

awarded 1 mark for correctly identifying the term.

💡 Key Knowledge

  • A tropism is a growth response of a plant towards or away from a directional stimulus.
  • Response to light is specifically called phototropism.
  • Response to gravity is gravitropism (or geotropism).

Part 03.2: Predicting Seedling Appearance

[2 Marks] • AO3 Analysis & Application

✅ Correct Matching Lines

  • 1 → Top diagram (shoot bent towards the light on the left).
  • 2 → Bottom diagram (tall shoot growing straight upwards).
awarded 1 mark per correct line. Max 2 marks.

💡 How Auxin Works

  • In unilateral light (Exp 1): Auxin accumulates on the shaded (right) side. In shoots, higher auxin concentration stimulates cell elongation, causing the shaded side to grow faster and bend towards the light.
  • In total darkness (Exp 2): Auxin is distributed evenly. The shoot grows straight up (etiolation) in search of light.

❌ Common Errors

Drawing multiple lines: The mark scheme states: "do not accept more than one line from a box on the left." If you change your mind, cross out the incorrect line clearly.

Part 03.3: Purpose of Experiment 2

[1 Mark] • AO3 Scientific Method

✅ Correct Answers (Any one)

  • To act as a control.
  • To show that the response in experiment 1 is caused by (one-sided) light.
  • To compare the effect of one-sided light with no light.

❌ Major Examiner Trap

Do NOT write "control variable". A control is a comparison test set up to prove the independent variable caused the observed effect. A control variable is a factor kept constant during an experiment.

Part 03.4: Improving Validity with a Third Experiment

[1 Mark] • AO3 Experimental Design

✅ Correct Answer

Tick: Shine light from all sides on the third seedling.

awarded 1 mark for this choice.

🧠 Exam Technique

To fully test directional light, scientists compare three conditions:

  1. Directional (one-sided) light → bends towards light.
  2. No light → grows straight up.
  3. All-round (uniform) light → grows straight up.

This confirms the bending is specifically due to unequal lighting, not merely the presence or total absence of light.

Part 03.5: Identifying a Control Variable

[1 Mark] • AO3 Variables

✅ Correct Answer

Tick: Keep each seedling at the same temperature.

❌ Why the Others are Incorrect

  • "Use the same size cardboard box..." → Experiment 1 has no box at all, so this cannot be controlled.
  • "Height above floor..." → Does not affect seedling growth rate or phototropic curvature.

Part 03.6: Stimulus for a Plant Root

[1 Mark] • AO1 Knowledge

✅ Correct Answers (Any one)

  • Gravity (geotropism/gravitropism)
  • Water or moisture (hydrotropism)
  • Chemicals / minerals / ions (e.g. nitrate)

❌ Rejected Terms

  • Do not write light (the question specifically excludes it).
  • Do not write vague terms like nutrients or food. Name a specific chemical such as "minerals" or "nitrate".

Part 03.7: Why Scientists Repeat Investigations

[2 Marks] • AO2 Working Scientifically

✅ Accepted Reasons (Give two distinct points)

  • Point 1: To identify and eliminate anomalies / account for natural variation (e.g., some seedlings may fail to germinate).
  • Point 2: To calculate a mean (average) to obtain a more representative value.
awarded 1 mark for each valid reason.

❌ Common "Zero-Mark" Phrases

Examiners consistently reject vague statements such as:

  • "To make it accurate" (repeating does not calibrate apparatus).
  • "To make it precise" or "To make it valid".
  • "To make it a fair test".

Always pair repeats with calculating a mean and spotting anomalies.

Topics

Biology · Required Practicals · B5: Homeostasis and Response · Required Practicals

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