AQA GCSE Biology Biology Paper 2 (Foundation), June 2024: Question 6

10 marks · Standard Demand difficulty · Extended Answer

Identify plant tropisms and hormones, state substances absorbed by roots, and plan an investigation into the effect of unidirectional light on seedling growth.

Practise this question

Question

Question text

06 Plants grow in response to the direction of light and to gravity.

06.1 What name is given to a plant’s growth response?

[1 mark]

Tick ( ) one box.

Accommodation

Adaptation

Tropism

06.2 Which substance controls the response to light in plant shoots?

[1 mark]

Tick ( ) one box.

Amylase

Auxin

Lactic acid 25

06.3 A plant root grows downwards in response to gravity.

Which two substances can the root absorb in larger amounts when it

grows downwards?

[2 marks]

Tick ( ) two es.

Carbon dioxide

Glucose

Nitrate ions

Protein

*24* Water 26

06.4 Plan an investigation to show the effect of light from one direction on the growth of

plant seedlings.

You should include:

• a control

• the measurements you would record

• any other observations you would make.

You may use the equipment shown in Figure 7 and any other laboratory apparatus.

[6 marks]

Figure 7

Mark scheme

Show the mark scheme

Question 6

AO /

Question Answers Extra information Mark

Spec Ref.

06.1 tropism 1 AO1

4.5.4.1

AO /

Spec Ref.

06.2 auxin 1 AO1

4.5.4.1

AO /

Spec Ref.

06.3 nitrate ions 1 AO1

4.2.3.2

– – – 4.5.4.1

water 1

AO /

Question Answers Mark

Spec Ref.

06.4 Level 3: The method would lead to the production of a valid 5–6 AO2

outcome. The key steps are identified and logically sequenced.

Level 2: The method would not necessarily lead to a valid 3–4 AO1

outcome. Most steps are identified, but the method is not fully

logically sequenced.

Level 1: The method would not lead to a valid outcome. Some 1–2 AO1

relevant steps are identified, but links are not made clear.

No relevant content 0

4.5.4.1

Indicative content RPA8

• one pot of seedlings placed in box with slit

• one pot of seedlings in dark

• one pot of seedlings in full light

• measure heights of shoots

• remeasure heights of shoots

• record a feature of appearance of seedlings

• detail of how bent shoots were measured eg use thread or

straighten them out

• calculate mean height increase for each group

• compare results (for each group of seedlings)

18 • control variable(s)

o same temperature

o same volume of water

o same soil type

o same age of seedlings

o same species / type of plant

o same time left for

For Level 3, a method comparing the growth of plants in light from

one direction with plants in full light / darkness along with a control

variable is required

Total Question 6 10

How to answer it

Plant Tropisms & Investigating Phototropism

What this question tests

This question assesses knowledge from Topic 4.5.4 (Plant Hormones) and Required Practical 8 (Investigating the effect of light on newly germinated seedlings):

Recall of tropism definitions and the role of the plant hormone auxin.
Understanding substances absorbed by plant roots from soil (water and mineral ions).
Planning an experimental method to investigate unidirectional light on seedling growth, including suitable controls, measurements, and control variables (Level 3 Extended Writing).

Question 06.1 • 1 Mark

Plant Growth Responses

Identifying the scientific term for directional plant growth

✅ Correct Answer

Tropism

1 Mark: Ticking the correct box for "Tropism".

💡 Key Knowledge

A tropism is the growth of a plant towards or away from a directional stimulus:

Phototropism: growth response to light.
Gravitropism (geotropism): growth response to gravity.

❌ Common Errors & Confusions

Accommodation: This is the eye changing lens shape to focus on near or far objects.
Adaptation: A feature that helps an organism survive in its environment (evolved over generations).

Question 06.2 • 1 Mark

Plant Hormones

Substance controlling the response to light in shoots

✅ Correct Answer

Auxin

1 Mark: Ticking the box for "Auxin".

💡 Key Knowledge

Auxin is produced in the shoot tips and diffuses backwards.
In shoots, auxin stimulates cell elongation.
When exposed to light from one side, auxin concentrates on the shaded side, causing those cells to elongate faster and bending the shoot towards the light.

❌ Distractors to Avoid

Amylase: An enzyme in saliva and the pancreas that breaks down starch into sugars.
Lactic acid: Produced during anaerobic respiration in animal muscles.

Question 06.3 • 2 Marks

Root Function & Gravitropism

Substances absorbed by plant roots from the soil

✅ Correct Answers

Nitrate ions
Water

2 Marks: 1 mark for each correctly ticked box.

💡 Key Knowledge

Water: Absorbed by root hair cells via osmosis; needed for photosynthesis, turgor, and transport.
Nitrate ions: Absorbed via active transport; provide nitrogen needed to synthesize amino acids and proteins.

❌ Common Errors

Carbon dioxide: Absorbed by leaves through stomata from the air, NOT through roots.
Glucose & Protein: Synthesized by the plant itself; they are never taken up from the soil.

Question 06.4 • 6 Marks

Required Practical Planning: Effect of Light Direction

Extended response investigation plan using provided apparatus

📐 Step-by-Step Practical Method

1 Set up 3 groups of seedlings:
• Experimental group: Pot placed in a cardboard box with a slit cut in one side, illuminated by a lamp.
• Control group 1: Pot in full, all-round light.
• Control group 2: Pot inside a completely sealed dark box (no light).

2 Control variables: Keep the temperature, type/species of seedlings, number of seedlings per pot, soil type, and volume of water added identical for all pots.

3 Initial measurement: Measure the initial height of each seedling shoot using a ruler (in mm or cm).

4 Incubation: Leave all pots for a set period (e.g. 3–5 days).

5 Final measurements & observations:
• Remeasure shoot heights (using a piece of damp thread along curved stems, then held against a ruler).
• Record visual appearance: direction of bending towards the slit, and stem/leaf colour.

6 Analysis: Calculate the mean change in height for each group and compare the bending and growth rates across conditions.

🧠 Exam Technique: Getting Level 3 (5–6 marks)

The mark scheme explicitly states:

Requirement for Level 3: You must describe a method comparing seedlings in unidirectional light against plants in full light or darkness, along with at least one named control variable.

Key checklist to secure 6/6:

Did you state how the one-directional light is achieved? (Box with slit).
Did you clearly identify the control setup? (Darkness or all-round light).
Did you give specific measurements? (Height before and after, thread along curved stem).
Did you state qualitative observations? (Direction of curvature, yellow vs green leaves).
Did you name 2+ controlled variables? (Water, temperature, plant species).

❌ Examiner Pitfalls to Avoid

Forgetting a control: Leaving out a dark box or all-directional light pot caps you below Level 3.
Vague measurements: Saying just "see how much it grows" loses marks. You must specify using a ruler to measure shoot height in mm/cm and measuring before and after.
Ignoring curved stems: Top candidates explain that curved stems must be measured accurately using thread straightened against a ruler.

💡 Expected Observations & Results

Box with slit: Shoots bend and grow towards the slit (positive phototropism).
All-round light: Shoots grow straight upwards and are healthy/green.
Complete darkness: Shoots grow tall and spindly (etiolation) with pale/yellow leaves, but grow straight upwards.

Topics

Biology · Required Practicals · B5: Homeostasis and Response · Required Practicals · B2: Organisation

Question and mark scheme from the AQA GCSE Biology examination, Biology Paper 2 (Foundation), June 2024. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.