AQA GCSE Biology Biology Paper 2 (Foundation), June 2025: Question 10

13 marks · Standard Demand difficulty · Extended Answer

Plan an investigation into the effect of the direction of light on plant seedling growth and explain how plant tropisms and hormones support plant survival.

Practise this question

Question

Question 10 begins with 'Tropisms help plants survive.' Part 10.1 asks 'What is geotropism?' (2 marks). Part 10.2 asks students to plan an investigation into the effect of light direction on seedling growth using equipment illustrated in Figure 15: a desk lamp, a 15 cm ruler, a cardboard box, and a cardboard box with a vertical slit cut into one side (6 marks). Part 10.3 asks to name the hormone controlling light response (1 mark). Part 10.4 is a multiple-choice question on how this hormone controls response to light (1 mark). Part 10.5 asks students to explain how a plant's response to light helps it survive (3 marks).
Question text

10 Tropisms help plants survive.

10.1 What is geotropism?

[2 marks]

10.2 Plan an investigation to find the effect of the direction of light on the growth of

plant seedlings.

You may use the equipment shown in Figure 15 and any other laboratory equipment.

[6 marks]

Figure 15

Extra space

Plant responses are controlled by hormones.

10.3 Which hormone controls a plant’s response to the direction of light?

[1 mark]

10.4 How does the hormone you named in Question 10.3 control the plant’s response to

the direction of light?

[1 mark]

Tick ( ) one box.

All parts of the plant have the same concentration of hormone.

The hormone has an effect when it breaks down.

*41There is an uneven distribution of the hormone.*

10.5 Explain how a plant’s response to light helps the plant survive.

[3 marks]

Mark scheme

Show the mark scheme Mark scheme for Question 10: 10.1 gives 1 mark for 'growth (response)' and 1 mark for 'due to gravity'. 10.2 provides a 3-level grid (1–6 marks) with indicative content including setting up seedlings in slit box versus all-round light/darkness, measuring initial/final shoot heights, calculating means, and identifying control variables. 10.3 awards 1 mark for 'auxin'. 10.4 awards 1 mark for 'there is an uneven distribution of the hormone'. 10.5 awards 3 marks for absorbing more light, leading to more photosynthesis, and producing more glucose.

Question 10

AO /

Question Answers Extra information Mark

Spec. Ref.

10.1 growth (response) ignore direction of growth 1 AO1

4.5.4.1

due to gravity 1

AO /

Question Answers Mark

Spec. Ref.

10.2 Level 3: The method would lead to the production of a valid 5–6 AO1

outcome. The key steps are identified and logically sequenced. 4.5.4.1

RPA8

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

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

sequenced.

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

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

No relevant content 0

Indicative content

• place a seedling in box with slit

• place a seedling in darkness or in all-round light

• measure initial heights of shoots

• measure final heights of shoots or measure shoots with a ruler

or measure the growth of shoots

• record a named feature of appearance of seedlings

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

straighten them out

• repeat with several seedlings

• calculate mean height increase for each condition

• compare results (for each condition)

control variable(s)

o same number of seedlings (per pot / condition)

o same temperature

o same volume of water

o same soil type / volume

o same age of seedlings 25

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 control

variables is required.

26 AO /

Spec. Ref.

10.3 auxin 1 AO1

4.5.4.1

AO /

Spec. Ref.

10.4 there is an uneven distribution of 1 AO1

the hormone 4.5.4.1

AO /

Spec. Ref.

10.5 leaves / plant receive(s) / 1 AO2

absorb(s) more light 4.5.4.1

4.4.1.1

(so) more photosynthesis 1 4.4.1.3

(which produces) more glucose allow (which produces) more 1

starch / carbohydrate / sugar

allow (which produces) more

(named) organic material / other

named organic substance

if no other marks awarded allow

1 mark for any two of the mark

points with no reference to

‘more’

Total Question 10 13

How to answer it

Plant Tropisms & Auxin Investigation

What this question tests

This question assesses knowledge of plant coordination and responses (AQA GCSE Biology Specification 4.5.4.1 & Required Practical 8). You need to know definitions of tropisms, design a controlled scientific method to investigate phototropism, identify the hormone auxin and its mechanism of action, and link plant responses logically to photosynthesis and survival.

Part 10.1: Defining Geotropism 2 Marks

Question: What is geotropism?

✅ Correct Answer (Mark Scheme)

  • Growth (or a growth response) [1 mark]
  • In response to / due to gravity [1 mark]

🧠 Exam Technique

A tropism is always a growth response, not simple rapid movement like an animal muscle response.

The mark scheme notes: ignore direction of growth. You do not need to specify positive or negative unless explicitly asked.

❌ Common Errors

  • Writing "the plant moves towards gravity" without mentioning growth.
  • Confusing geotropism (gravity) with phototropism (light) or hydrotropism (water).

Part 10.2: Required Practical 8 – Investigating Light Direction 6 Marks

Question: Plan an investigation to find the effect of the direction of light on the growth of plant seedlings using the provided equipment.

Level 3 Requirement (5–6 marks): The method must lead to a valid outcome. It must include a direct comparison between unilateral light (cardboard box with a slit) and a control condition (darkness or all-round light), describe accurate growth measurements, and detail control variables.

✅ Model 6-Mark Method

  1. Set up conditions: Place one dish of seedlings inside the cardboard box with a side slit next to the lamp (unidirectional light). Place a second identical dish in either complete darkness (closed box) or all-round light (control).
  2. Initial measurements: Measure the initial shoot height of each seedling using a ruler (in mm).
  3. Incubation: Leave both sets in the same room for a set period of time (e.g. 3 to 5 days).
  4. Final measurements: Measure the final height of the seedlings. If the shoots have curved, straighten them out gently or use damp thread along the curve and measure the thread against the ruler. Record the direction of growth.
  5. Repeats: Use at least 10 seedlings in each dish to calculate a mean height increase for each condition.

🧠 Key Control Variables

To secure Level 3, you must explicitly state at least three controlled variables:

  • Number of seedlings per dish (e.g. 10 seedlings).
  • Volume of water added to each dish.
  • Temperature of the room/environment.
  • Same plant species/type (e.g. cress or mustard seeds) and same initial age.
  • Same incubation time (e.g. exactly 72 hours).

❌ Examiner Warning: Level Demoters

  • No control group: Setting up only the box with a slit limits you to Level 1 or 2. You must compare against darkness or all-round light.
  • Measuring curved shoots: Forgetting to explain how to measure a curved shoot (using thread or straightening against a ruler).
  • Vague quantities: Stating "give them some water" instead of "add 5 cm³ of water using a measuring cylinder".

Parts 10.3 & 10.4: Hormone Identification & Mechanism 2 Marks Total

10.3: Plant Hormone

Answer: Auxin [1 mark]

(Auxin controls phototropism and gravitropism in plant shoots and roots).

10.4: Mechanism of Action

Tick box selection:

☑ There is an uneven distribution of the hormone. [1 mark]

💡 Detailed Mechanism (How Auxin Works in Shoots)

  • Auxin is produced in the shoot tips and diffuses downwards.
  • When light shines from one side (unilateral light), auxin moves to the shaded side.
  • A higher concentration of auxin on the shaded side causes cells on that side to elongate faster than cells on the illuminated side.
  • This uneven growth causes the shoot to bend towards the light (positive phototropism).

Part 10.5: Survival Advantage of Phototropism 3 Marks

Question: Explain how a plant's response to light helps the plant survive.

✅ 3-Step Marking Chain

  1. Leaves / plant receive or absorb more light [1 mark]
  2. (So) more photosynthesis occurs [1 mark]
  3. (Which produces) more glucose / carbohydrate / sugar / energy for growth [1 mark]

❌ The "Comparative" Trap

Notice the word more in every mark point!

If you write "it absorbs light to photosynthesise and make glucose" without using comparative language, the mark scheme specifies you can only receive a maximum of 1 mark total.

Always show the advantage over a plant that doesn't bend: more light = more photosynthesis = more glucose.

🧠 How to Answer "Explain Survival" Questions

Whenever an exam question links a plant adaptation to survival:

Light / Adaptation → Rate of Photosynthesis → Glucose for Growth / Respiration

Always state the end product (glucose) and what it is used for (respiration, cell walls / cellulose, protein synthesis, storage as starch).

Topics

Biology · Required Practicals · B5: Homeostasis and Response · B4: Bioenergetics · 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.