AQA GCSE Biology Biology Paper 2 (Higher), June 2025: Question 7

13 marks · Standard Demand difficulty · Extended Answer

Analyze a ruler-drop investigation of reaction time, calculate the median and mean reaction time with unit conversions, suggest improvements, and describe how the nervous system coordinates the response.

Practise this question

Question

Question 7 illustrates a ruler drop test to investigate reaction time. Figure 7 shows Student A holding a metre rule vertically just above Student B's open hand, followed by Student B catching the ruler at the 18 cm mark. Table 3 lists results for seven tests: 18, 15, 12, 16, 14, 23, and 14 cm, with a mean of 16 cm. Part 07.1 asks to select the median value from 14 cm, 15 cm, 16 cm, or 18 cm. Part 07.2 requires calculating the mean reaction time in milliseconds to 3 significant figures using the formula t = sqrt(2d / 980). Part 07.3 asks for two ways to improve the investigation without repeating tests. Part 07.4 asks for a 6-mark description of how Student B's nervous system coordinated the catching response.
Question text

07 Two students investigated reaction time.

This is the method used.

1. Student A holds a metre rule just above student B’s hand, as shown in Figure 7.

2. Student A lets go of the metre rule.

3. Student B catches the metre rule as quickly as possible.

4. Student A writes down the reading from the scale on the metre rule.

5. Students A and B repeat steps 1 to 4 another six times.

Figure 7

Table 3 shows the results.

Table 3

Reading on metre rule

Test

in cm

1 18

2 15

3 12

4 16

5 14

6 23

7 14

Mean 21 16

07.1 What is the median result in Table 3?

[1 mark]

*20*Tick ( ) one box.

14 cm 15 cm 16 cm 18 cm

07.2 Calculate student B’s mean reaction time.

Use the equation:

Give your answer in milliseconds.

Give your answer to 3 significant figures.

Use data from Table 3.

[4 marks]

Mean reaction time (3 significant figures) = milliseconds

The method and Figure 7 are repeated below.

1. Student A holds a metre rule just above student B’s hand, as shown in Figure 7.

2. Student A lets go of the metre rule.

3. Student B catches the metre rule as quickly as possible.

*21*4. Student A writes down the reading from the scale on the metre rule.

5. Students A and B repeat steps 1 to 4 another six times.

Figure 7

07.3 Describe two ways the students could improve the investigation.

Do not refer to repeating results in your answer.

[2 marks]

07.4 Catching the rule was a response to a stimulus.

Describe how student B’s response was coordinated by the nervous system.

[6 marks]

Extra space

Mark scheme

Show the mark scheme The mark scheme provides answers for Question 7: 07.1 gives 15 cm (1 mark). 07.2 awards 4 marks for substitution into the formula (t = sqrt(32/980)), obtaining 0.18070... s, converting to milliseconds (180.7 ms), and rounding to 3 significant figures (181 ms). 07.3 awards 2 marks for valid improvements such as using a ruler with millimetre divisions, ensuring a fixed starting alignment, dropping without warning, or supporting the arm on a table. 07.4 awards up to 6 marks for describing the nervous pathway: photoreceptors in the eye detecting the falling ruler, nerve impulses traveling along the sensory neurone via the optic nerve to the brain, crossing synapses, passing along motor neurones to effectors (muscles in the hand/fingers) to contract.

Question 7

AO /

Question Answers Extra information Mark

Spec. Ref.

07.1 15 cm 1 AO3

4.5.2.1

RPA7

AO /

Spec. Ref.

07.2 allow correct conversion to AO2

milliseconds at any point in the 4.5.2.1

calculation RPA7

substitution

2 × 16 32

t = � (seconds) allow t = � (seconds) 1

980 980

correct answer

t = 0.18070... (seconds) all subsequent marks can be 1

awarded using an incorrectly

calculated value

conversion to milliseconds

t = 180.7 (milliseconds) 1

rounding to 3 significant figures

181 (milliseconds) allow student’s incorrectly / not 1

converted answer correctly

rounded to 3 significant figures

AO /

Spec. Ref.

07.3 any two from: 2 AO3

4.5.2.1

• use ruler with smaller / mm allow use a ruler with a more RPA7

divisions precise scale

allow use a ruler with a better

resolution

ignore use a more accurate ruler

• align 0 cm on ruler with top / allow same starting position of

bottom of (student’s B’s) ruler above (student B’s) hand

thumb

• same distance between

(student B’s) finger(s) and

thumb

• (student B) supports arm / allow make sure (student B’s)

hand / wrist / elbow on bench hand is stationary

/ table

• use same hand (each time) allow use dominant or non-

dominant hand each time

• convert distance to time

• allow drop ruler without allow use of mechanical /

warning electronic device to hold and

or drop ruler

drop ruler at random time

intervals

allow idea of controlling

distraction / caffeine / sleep /

alcohol

allow use a computer program

(to measure reaction time)

AO /

Spec. Ref.

07.4 receptor (in eyes) detect allow retina detects stimulus / 1 AO1

stimulus / movement movement 4.5.2.1

4.5.2.2

impulses generated / allow electrical signals 1 4.5.2.3

transmitted / travel generated / transmitted / travel

ignore messages / information

(from) sensory neurone (to 1

relay neurone) to motor neurone

22 (along) optic nerve to brain ignore CNS / spinal cord 1

chemical crosses synapses 1

between neurones

effector / muscle in fingers / 1

hand / arm contracts (to catch

the ruler)

Total Question 7 13

How to answer it

AQA GCSE Biology: Investigating Reaction Time

Required Practical 7 & Nervous Coordination | Question 7 Walkthrough
📋 WHAT THIS QUESTION TESTS

This question assesses mathematical and practical skills alongside core physiological knowledge of human coordination:

  • Data Handling (AO3): Finding the median from an unordered set of raw experimental results.
  • Mathematical Modelling (AO2): Substituting into a physics formula with a square root, unit conversion (s to ms), and rounding to 3 significant figures.
  • Required Practical 7 Skills (AO3): Identifying controlled variables, improving precision, and reducing measurement errors in the ruler drop test.
  • Nervous System Response (AO1): Detailing the complete pathway of voluntary coordination: receptor, sensory neurone, CNS (brain/optic nerve), synapse, motor neurone, and effector.
PART 07.1 • 1 MARK

Finding the Median from Table 3

Data Processing: Calculating the Median Drop Distance

✅ Correct Answer

15 cm (Tick the second box)

[1 Mark]

📐 How to Find the Median

  1. Extract the 7 measurements: 18, 15, 12, 16, 14, 23, 14
  2. Place them in ascending order:
    12, 14, 14, 15, 16, 18, 23
  3. Pick the middle value (the 4th value): 15

❌ Common Errors

  • Picking the Mean: Choosing 16 cm because it is shown at the bottom of Table 3.
  • Picking the Middle of the Table: Choosing Test 4 (16 cm) without ordering the numbers first!
  • Picking the Mode: Choosing 14 cm because it appears twice.
PART 07.2 • 4 MARKS

Calculating Reaction Time

Formula Substitution, Unit Conversion, and Significant Figures

📐 Step-by-Step Calculation

Formula given: t = √(2d / 980)

  1. Identify mean distance (d):
    From Table 3, mean distance d = 16 cm
  2. Substitute into formula: Mark 1
    t = √((2 × 16) / 980) = √(32 / 980) = √(0.032653...)
  3. Calculate time in seconds: Mark 2
    t = 0.180701... s
  4. Convert to milliseconds (× 1000): Mark 3
    0.180701... × 1000 = 180.701... ms
  5. Round to 3 significant figures: Mark 4
    180.701... → 181 ms

❌ Calculation Traps & Examiner Commentary

  • Unit Error: Forgetting to multiply by 1000 to convert seconds to milliseconds (giving 0.181 instead of 181).
  • Rounding Error: Rounding to 3 decimal places instead of 3 significant figures (e.g. leaving 180.7).
  • Order of Operations: Calculating √2 × 16 / 980 instead of taking the square root of the whole fraction.
  • Note: Full error-carried-forward (ECF) applies if an arithmetic mistake was made earlier, provided subsequent steps and rounding are correct.
PART 07.3 • 2 MARKS

Improving the Ruler Drop Investigation

RPA 7: Precision and Control Variables (Excluding Repetition)

✅ Acceptable Improvements (Any Two)

  • Higher Precision: Use a ruler with smaller divisions / millimetre (mm) markings.
  • Consistent Starting Point: Align 0 cm on the ruler exactly level with the top or bottom of the thumb.
  • Control Hand Position: Keep the thumb and finger spacing constant before each drop.
  • Prevent Movement: Rest the forearm/wrist on a bench or table.
  • Control Side: Always use the same hand (e.g. dominant hand).
  • Prevent Anticipation: Drop the ruler with no warning or at random time intervals (or use an automated electronic drop mechanism).
  • Extraneous Factors: Control distractions, caffeine intake, or room lighting.

🧠 Exam Technique: Reading the Prompt

The question explicitly states: "Do not refer to repeating results in your answer."

  • Writing "repeat and calculate a mean" or "remove anomalies" scores 0 marks.
  • Avoid vague answers like "use a better ruler" or "be more accurate". You must specify how (e.g. "millimetre scale" or "higher resolution").
PART 07.4 • 6 MARKS

Nervous Coordination of the Response

Tracing the Full Coordination Pathway (Stimulus → Effector)

Stimulus (Falling ruler) → Light Receptors (Retina) → Sensory Neurone (Optic nerve) → Brain (CNS) → Motor Neurone → Effector (Hand Muscles)

💡 The 6 Marking Points Breakdown

  1. Receptor: Light receptors in the eye (retina) detect the stimulus (the ruler dropping/moving). 1 Mark
  2. Electrical Impulses: Electrical impulses are generated and transmitted. 1 Mark
  3. Sensory to Motor: Impulses travel from sensory neurone (via relay neurones) to motor neurone. 1 Mark
  4. Route via Brain: Impulses travel along the optic nerve to the brain. 1 Mark
  5. Synapse: Chemical neurotransmitters diffuse across synapses (gaps) between neurones. 1 Mark
  6. Effector Response: The effector is the hand/finger muscles which contract to catch the ruler. 1 Mark

❌ Examiner Traps to Avoid

  • Calling it a Reflex Arc: This is a voluntary response involving visual processing in the brain, NOT a spinal reflex. Stating "spinal cord coordinates the reflex" loses the coordination mark!
  • Using "Messages": Do not write "messages" or "signals" travelling along nerves. Always write electrical impulses.
  • Vague Effector: Simply writing "the hand moves" is insufficient. Name the muscle as the effector and state that it contracts.
  • Missing the Synapse: Many students describe the neurones but forget to mention chemical transmission across the synapse.

Topics

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

Question and mark scheme from the AQA GCSE Biology examination, Biology Paper 2 (Higher), June 2025. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.