AQA GCSE Combined Science: Trilogy Biology Paper 2 (Foundation), 2021: Question 2

9 marks · Standard Demand difficulty · Short Answer

Analyze an investigation into the effect of caffeine on reaction time, including variables, nervous system components, and data interpretation.

Practise this question

Question

A multi-part exam question about an experiment investigating the effect of coffee on reaction time. It includes a description of the method, multiple-choice questions on variables and the nervous system (receptor and effector), and a table showing reaction times in milliseconds for five students before and after drinking coffee. Students are asked to identify the dependent variable, control variables, explain the 15-minute wait, identify the eye as a receptor and muscle as an effector, and interpret the data in the table.
Question text

02 Caffeine is a drug that affects reaction time.

Coffee is a drink that contains caffeine.

Five students investigated the effect of drinking coffee on their reaction time.

Each student sat in front of a computer screen showing a reaction timer.

This is the method used.

1. Press any key on the keyboard when the colour of the screen changes to green.

2. Record the reaction time shown on the computer screen.

3. Drink coffee containing caffeine.

4. Wait 15 minutes then repeat steps 1 and 2.

02.1 What is the dependent variable in the investigation?

[1 mark]

Tick ( ) one box.

The coffee containing caffeine

The number of students

The reaction time

02.2 Give two control variables the students should have used.

[2 marks]

02.3 Why did the students wait 15 minutes after drinking the coffee before

repeating the test?

[1 mark]

02.4 Responding to the colour change of the screen involves a receptor in the student.

Where is the receptor in the student?

[1 mark]

Tick ( ) one box.

Ear

Eye

Skin

02.5 Responding to the colour change of the screen involves an effector in the student.

What is the effector in the student?

[1 mark]

Tick ( ) one box.

Brain

Gland

Muscle

Spinal cord 8

Table 1 shows the results.

Table 1

Reaction time in milliseconds

Student

*07* Before drinking coffee After drinking coffee

1 385 255

2 420 291

3 285 265

4 871 259

5 463 247

02.6 What is the effect of drinking coffee on reaction time?

Use Table 1.

[1 mark]

02.7 Which student had the smallest change in reaction time after drinking coffee?

[1 mark]

Tick ( ) one box.

Student 1

Student 2

Student 3

Student 4

Student 5

*0082.*8 The students decided that one of the results was anomalous.

What should the students do with the anomalous result when calculating the mean

change in reaction time?

[1 mark]

Mark scheme

Show the mark scheme The mark scheme for question 02, totaling 9 marks. It lists acceptable answers for identifying the dependent variable as reaction time, various control variables like age and volume of coffee, the reason for waiting as allowing caffeine to be absorbed, identifying the eye as the receptor and muscle as the effector, noting that reaction time decreased, identifying student 3 as having the smallest change, and explaining how to handle an anomalous result by excluding it from the mean calculation.

AO /

Question Answers Extra information Mark

Spec. Ref.

02.1 the reaction time 1 AO1

4.5.2

RPA6

02.2 any two from: 2 AO1

• age 4.5.2

• sex allow gender RPA6

• previous intake of caffeine /

coffee that day

• usual intake of caffeine /

coffee (on previous days)

• concentration of caffeine / if neither given allow amount /

coffee mass of caffeine / drink or

• volume of caffeine / coffee type / brand of coffee for 1

mark

• time of day

• amount / length of sleep allow fatigue

• health allow other drugs taken

• body mass allow (body) weight

• same / type of reaction time

program / software

• same keyboard

• prior experience with the

reaction timer

02.3 any one from: 1 AO3

• (time) for the coffee / caffeine 4.5.2

to work RPA6

• (time) for coffee / caffeine to allow (time) for the coffee /

be absorbed caffeine to be digested

• (time) for caffeine to reach allow (time) for coffee to reach

the brain the brain

• (time) for coffee / caffeine to

get round the body

02.4 eye 1 AO2

4.5.2

RPA6

02.5 muscle 1 AO2

4.5.2

RPA6

02.6 (reaction time is) decreased allow reaction time is shorter 1 AO2

allow reactions are faster 4.5.2

allow (reaction) time is quicker RPA6

02.7 student 3 1 AO3

4.5.2

RPA6

02.8 leave it out (and divide sum of ignore repeat the test 1 AO3

the others by 4) 4.5.2

or RPA6

divide the sum of the others by 4

Total 9

How to answer it

Investigating Caffeine and Reaction Times

What this question tests

This question focuses on Required Practical 6 (RPA6). It assesses your understanding of experimental variables (independent, dependent, and control), the biological components of a reflex arc (receptors and effectors), and the ability to interpret data from a results table.

Part 02.1 & 02.2

Experimental Variables

Correct Answers

  • 02.1: The reaction time
  • 02.2: (Any two) Age, Sex (Gender), Previous caffeine intake, Volume of coffee, Concentration of caffeine, Time of day.

Exam Technique

Remember the "ID" rule:

  • Independent = I change (The coffee).
  • Dependent = Data collected (The reaction time).

Common Errors

In 02.2, students often lose marks by being too vague. Don't just write "The coffee." You must specify what about it is being controlled, such as the volume or the type/brand of coffee.

Part 02.3, 02.4 & 02.5

The Reflex Arc & Biology

Key Knowledge

  • Receptors: Cells that detect a stimulus (change in environment).
  • Effectors: Muscles or glands that bring about a response.

Correct Answers

  • 02.3: To allow time for caffeine to be absorbed or reach the brain.
  • 02.4: Eye (detects the light change).
  • 02.5: Muscle (presses the key).

Examiner Insight

For 02.3, the mark scheme is generous—you can say "to reach the brain" or "to be digested." However, "to reach the brain" is the most scientifically accurate way to describe a drug's effect on reaction time.

Part 02.6, 02.7 & 02.8

Data Analysis

02.7 Calculation: Finding the Smallest Change

To find the smallest change, you must subtract the "After" value from the "Before" value for each student:

  1. Student 1: 385 - 255 = 130 ms
  2. Student 2: 420 - 291 = 129 ms
  3. Student 3: 285 - 265 = 20 ms (Smallest)
  4. Student 4: 871 - 259 = 612 ms
  5. Student 5: 463 - 247 = 216 ms

Correct Answers

  • 02.6: Reaction time decreased (or reactions became faster).
  • 02.7: Student 3.
  • 02.8: Ignore it / exclude it from the mean calculation.

Common Errors

02.6: Be careful with your wording! If reaction time decreases, it means you are faster. Don't say "reaction time got faster"—that is confusing. Say "reaction time decreased" or "reactions were faster."

Handling Anomalies (02.8)

When asked what to do with an anomaly when calculating a mean, the answer is always to exclude it. Do not say "repeat the experiment" unless the question asks how to improve the overall investigation.

Marking Note: For 02.8, you can also say "divide the sum of the other 4 results by 4."

Topics

Biology · B5: Homeostasis and Response

Question and mark scheme from the AQA GCSE Combined Science: Trilogy examination, Biology Paper 2 (Foundation), 2021. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.