AQA GCSE Biology Biology Paper 1 (Foundation), November 2021: Question 6

12 marks · Standard Demand difficulty · Short Answer

Evaluate a bell jar model of the breathing system, identify control variables, calculate the percentage increase in breathing rate during exercise from a line graph, and explain the physiological response to exercise.

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Question

Question 6 features Figure 12 showing a bell jar model of human breathing, containing a Y-shaped glass tube passing through a bung, two balloons attached to the tube ends, inside a glass bell jar with a flexible rubber sheet at the bottom. Parts 06.1 to 06.3 ask to identify which part of the breathing system the glass tube represents, explain two limitations of the model, and state two controlled variables from an investigation on exercise and breathing rate. Figure 13 shows a line graph of breathing rate in breaths per minute against time in minutes (0 to 12 minutes). The graph starts at 20 breaths/min at 0 min, rises to 42 breaths/min at 8 min, and then drops back to 20 at 12 min. Parts 06.4 to 06.7 ask for a percentage increase calculation using a given formula, an explanation for the increased breathing rate during running, another measurement to show the effect of exercise, and an effect of smoking on the body.
Question text

06 Figure 12 shows a model used to demonstrate human breathing.

Figure 12

06.1 Which part of the breathing system is represented by the glass tube?

[1 mark]

Tick ( ) one box.

Alveoli

Capillaries

Lung

Trachea 27

The model in Figure 12 represents the human breathing system.

A teacher said:

“The model does not represent the human breathing system very well.”

06.2 Give two reasons why the teacher is correct.

[2 marks]

A scientist investigated the effect of exercise on breathing rate.

This is the method used.

1. Record the breathing rates of 10 male non-smokers at rest.

2. Tell each man to run on a treadmill at the same speed for 8 minutes.

3. Record the breathing rate of each man every 2 minutes.

4. Continue to record the breathing rate of each man for 4 minutes after he

stops running.

06.3 Give two variables the scientist controlled in the investigation.

[2 marks]

Figure 13 shows the data collected from one of the men.

Figure 13

06.4 Calculate the percentage increase in the man’s breathing rate between 0 minutes and

8 minutes.

[3 marks]

*28* Use the equation:

(breathing rate at 8 minutes − breathing rate at 0 minutes)

percentage increase = × 100

breathing rate at 0 minutes

Percentage increase = %

06.5 Explain why the man’s breathing rate increased when he was running.

[2 marks]

06.6 Give one measurement that could be taken to show a different effect of exercise on

the body.

Do not refer to breathing rate in your answer.

[1 mark]

06.7 The men in the investigation were all non-smokers.

Give one effect that smoking can have on the body.

[1 mark]

Mark scheme

Show the mark scheme Mark scheme for question 6 detailing 12 marks: 06.1 requires 'trachea' (1 mark). 06.2 allows reasons such as only one air space/no alveoli, blood vessels not represented, rigid glass tube, or bell jar not moving like ribs (2 marks). 06.3 allows speed, type of exercise, sex, non-smokers, or exercise duration (2 marks). 06.4 awards 1 mark for reading 0 min = 20 and 8 min = 42, 1 mark for substitution ((42-20)/20 * 100), and 1 mark for 110% (3 marks). 06.5 requires oxygen intake and respiration/energy release for muscles, or carbon dioxide removal (2 marks). 06.6 accepts heart/pulse rate, breathing volume, sweat, or body temperature (1 mark). 06.7 accepts lung cancer, cardiovascular disease, or high blood pressure (1 mark).

AO /

Question Answers Extra information Mark

Spec. Ref.

06.1 trachea 1 AO2

4.2.2.2

06.2 any two from: 2 AO3

• only one air space (per 4.2.2.2

balloon)

or

alveoli not represented

• blood vessels / capillaries not

represented

• bronchioles not represented do not accept bronchi not

represented

• glass tube not flexible (like

trachea / bronchi)

• bell jar does not move during

breathing (like ribs)

• ribs have gaps between them

• rib cage contains muscles

• pleural cavity not represented

06.3 any two from: 2 AO2

• speed (of treadmill) 4.4.2.2

• type of exercise or all were

running

• (biological) sex or all male

• all were non-smokers

• time spent running allow ran for 8 minutes

ignore reference to time interval

for counting breaths

06.4 0 minutes = 20 1 AO2

8 minutes = 42 allow value for 8 minutes in the 4.4.2.2

range 41.5 to 42.5

(42 - 20) ÷ 20 × 100 allow correct substitution from 1

or incorrect graph readings (i.e. ±1

22 ÷ 20 × 100 small square) at 0 minutes and /

or 8 minutes

110 (%) allow correct calculation from 1

incorrect graph readings from

previous step

06.5 to get more oxygen (into the allow using more oxygen (in 1 AO2

blood) muscles) 4.4.2.2

4.4.2.1

for use in respiration allow to reduce anaerobic 1 15

or for releasing energy (for respiration

muscle contraction)

do not accept produces / makes

/ creates energy

or

to remove more carbon dioxide

(1)

produced in respiration (1)

06.6 any one from: 1 AO3

• heart / pulse rate allow heart beat per minute 4.4.2.2

• depth / volume of breathing

• volume of sweat allow amount of sweat

• body temperature

allow body mass / measurement

06.7 any one from: 1 AO1

• (lung) cancer 4.2.2.6

• increased blood pressure

• lung disease allow named example of lung

disease e.g. asthma

• low birth weight in babies of

mothers who smoke

• increased risk of heart /

cardiovascular disease

allow persistent cough

ignore cough unqualified

Total 12

How to answer it

Human Breathing System, Exercise & Respiration

What This Question Tests

This question assesses fundamental human biology practical and theoretical concepts across AQA Biology:

  • Organ System Models: Evaluating how well mechanical models (the bell jar) represent human gas exchange structures.
  • Experimental Design: Identifying control variables in human physiological investigations.
  • Maths in Biology: Reading line graphs accurately and calculating percentage increase using a given equation.
  • Physiology of Exercise: Explaining why breathing rate increases (cellular respiration, oxygen demand, and carbon dioxide removal).
  • Health & Disease: Measuring physical effects of exercise and recalling the health risks of smoking.
Question 06.1

Bell Jar Model: Identifying Anatomy

Tick one box to identify the part represented by the glass tube [1 mark]

✅ Correct Answer

Trachea (windpipe)

Award 1 mark for the box next to "Trachea" checked.

💡 Bell Jar Model Analogy

  • Glass tube (top): Trachea
  • Y-junction split: Bronchi
  • Balloons: Lungs
  • Bell jar (glass): Ribcage / Thorax wall
  • Rubber sheet (bottom): Diaphragm
Question 06.2

Evaluating the Breathing System Model

Give two reasons why the teacher is correct that the model does not represent the human breathing system very well [2 marks]

✅ Acceptable Answers (Any Two)

  • The bell jar is rigid and cannot move in and out / up and down (unlike real ribs).
  • There are no intercostal muscles / ribcage muscles present.
  • The balloons are simple hollow bags with only one air space per balloon (alveoli and bronchioles are not represented).
  • No blood vessels / capillaries are present around the lungs.
  • The glass tube is rigid (real trachea/bronchi contain cartilage rings and are flexible).
  • No pleural cavity / pleural membranes shown.
1 mark for each valid limitation (max 2 marks).

❌ Common Misconceptions

  • Do NOT say: "Bronchi are missing." The Y-shaped split in the tube already represents the bronchi, so this will be rejected!
  • Vague comments: Saying "it isn't alive" or "it is made of glass" without explaining the biological difference will not score.
Question 06.3

Controlled Variables in Exercise Investigations

Give two variables the scientist controlled in the investigation [2 marks]

✅ Acceptable Answers (Any Two)

  • Speed of the treadmill.
  • Duration of exercise: Time spent running (8 minutes).
  • Type of exercise: Running on a treadmill.
  • Biological sex: All participants were male.
  • Smoking status: All participants were non-smokers.
1 mark per valid controlled variable identified from the method (max 2).

🧠 Exam Technique: Look at the Method

Read steps 1–4 carefully. Whenever a method explicitly fixes something for everyone (e.g., "10 male non-smokers", "same speed", "for 8 minutes"), those are your control variables!

Examiner note: Ignore mentions of recording intervals (e.g., "every 2 minutes")—that is how data is logged, not a condition of the participants.
Question 06.4

Calculating Percentage Increase

Calculate the percentage increase in breathing rate between 0 and 8 minutes [3 marks]

📐 Step-by-Step Calculation

Step 1: Read values from Figure 13 accurately
Breathing rate at 0 minutes = 20 breaths per minute
Breathing rate at 8 minutes = 42 breaths per minute (allow 41.5 to 42.5)
1 mark awarded for reading both values correctly.
Step 2: Substitute into the provided equation
Difference = 42 − 20 = 22
Percentage increase = (22 / 20) × 100
1 mark awarded for correct substitution into the formula.
Step 3: Calculate the final percentage
22 ÷ 20 = 1.1
1.1 × 100 = 110%
1 mark for the correct answer: 110 (%)

❌ Common Pitfalls

  • Wrong denominator: Dividing by the final value (42) instead of the initial value at 0 minutes (20).
  • Misreading the y-axis: Each small grid square vertically represents 1 breath per minute. Ensure your ruler is aligned horizontally to read exactly 42 at 8 minutes.

🧠 Error-Carried-Forward (ECF)

If you misread the point at 8 minutes (e.g., writing 41), you can still gain 2 marks if your substitution and final calculation match your readings perfectly.

Question 06.5

Explaining Increased Breathing Rate

Explain why the man's breathing rate increased when he was running [2 marks]

✅ Model Answer (2 Marks)

Running requires more muscle contraction, which needs more energy from aerobic respiration [1 mark].

Therefore, breathing rate increases to supply more oxygen to the blood / muscles (or to remove more carbon dioxide produced by respiration) [1 mark].

❌ Major Mark-Loser: "Creating" Energy

Never write: "respiration produces energy" or "creates energy". Energy cannot be created!

Always write: respiration releases energy, or transfers energy.

Question 06.6

Alternative Physiological Measurements

Give one measurement that could be taken to show a different effect of exercise on the body (do NOT refer to breathing rate) [1 mark]

✅ Acceptable Answers (Any One)

  • Heart rate / pulse rate (or beats per minute)
  • Body temperature
  • Volume / amount of sweat produced
  • Depth of breathing / tidal volume (volume per breath)

🧠 Read the Negative Command

The prompt explicitly warns: "Do not refer to breathing rate in your answer." Always double-check you haven't mentioned breathing frequency or breaths per minute.

Question 06.7

Health Effects of Smoking

Give one effect that smoking can have on the body [1 mark]

✅ Acceptable Answers (Any One)

  • (Lung) cancer
  • Cardiovascular disease / coronary heart disease / heart attack
  • Increased blood pressure
  • Chronic lung disease (e.g., COPD, emphysema, bronchitis)
  • Low birth weight in babies of smoking mothers
  • Persistent cough

❌ Be Specific

Do NOT write just "cough" unqualified—the mark scheme requires a persistent cough or a specific clinical disease.

Topics

Biology · B2: Organisation · B4: Bioenergetics

Question and mark scheme from the AQA GCSE Biology examination, Biology Paper 1 (Foundation), November 2021. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.