AQA GCSE Combined Science: Trilogy Biology Paper 1 (Higher), 2020: Question 3

14 marks · Standard Demand difficulty · Extended Answer

Answer questions about the health effects of being overweight, calculate height from BMI, identify a weight category from a chart, describe how diet and exercise affect body mass, and explain body changes during and after vigorous exercise including anaerobic respiration.

Practise this question

Question

The question page contains five parts labeled 03.1 to 03.5 about body mass, BMI, and exercise. Part 03.1 asks for one disease related to being overweight; part 03.2 gives the equation BMI = body mass in kg divided by height in m squared and asks to calculate the height of a woman with BMI 27 and body mass 68.1 kg; part 03.3 shows a height-body mass chart for adults with height from 1.5 to 2.0 m on the y-axis and body mass from 40 to 160 kg on the x-axis, divided into shaded regions labeled Underweight, Healthy weight, Overweight, and Obese, then asks which category describes the woman from 03.2. Part 03.4 asks how the balance between mass of food eaten and amount of exercise controls body mass, and part 03.5 asks for an explanation of changes in the body during and after long periods of vigorous exercise when anaerobic respiration occurs, with lined spaces for extended written answers.
Question text

03 Being overweight can affect the health and life expectancy of a person.

03.1 Give one disease related to being overweight.

[1 mark]

03.2 Body mass index (BMI) helps to show if a person has a healthy body mass for

their height.

BMI is calculated using the equation:

body mass in kg

BMI = 2

(height in m)

A woman has a BMI of 27 and a body mass of 68.1 kg

Calculate the woman’s height in metres.

[3 marks]

Height = m

03.3 Figure 4 shows a height-body mass chart for adults.

Figure 4

Which weight category describes the woman in Question 03.2?

[1 mark]

Tick ( ) one box.

Underweight

Healthy weight

Overweight

Obese 14

03.4 People are encouraged to control their body mass with diet and exercise.

Describe how the balance between the mass of food eaten and the amount of

exercise a person does controls body mass.

[3 marks]

03.5 During long periods of vigorous exercise the body respires anaerobically.

Explain the changes that happen in the body during and after vigorous exercise.

[6 marks]

Mark scheme

Show the mark scheme The mark scheme is a table for questions 03.1 to 03.5 with accepted answers, extra guidance, marks, and specification references. It awards 1 mark in 03.1 for one disease linked to being overweight such as Type 2 diabetes, coronary heart disease, high blood pressure, cancer, or depression; 3 marks in 03.2 for rearranging the BMI equation and calculating height as about 1.59 m; and 1 mark in 03.3 for identifying the category as overweight, consistent with the calculated height. For 03.4 it gives up to 3 marks for explaining energy intake versus energy transferred in exercise and how this affects body mass, and for 03.5 it uses level-based marking up to 6 marks for explaining changes during exercise such as increased breathing and heart rate, oxygen demand, lactic acid formation and oxygen debt, and after exercise the continued elevated breathing and heart rate to remove lactic acid and repay oxygen debt.

AO /

Question Answers Extra information Mark

Spec. Ref.

ignore obesity

03.1 any one from: 1 AO1

• (Type 2) diabetes do not accept Type 1 diabetes 4.2.2.5

• (coronary / ischaemic) heart allow cardiovascular disease 4.2.2.6

disease / CHD ignore heart attack / failure

• high blood pressure

• cancer

• depression

allow (osteo)arthritis

03.2 68.1 1 AO2

27 = 2

height 4.2.2.5

68.1 4.2.2.6

height2 = 68.1 ÷ 27 allow height = � 1

or or

height2 = 2.522(r) / 2.52 / 2.5 allow height = �2.522(r)

height = 1.59 (m) allow a correctly rounded value 1

if 2.5 is given in step 2 allow an

answer of 1.58 (m)

03.3 overweight answer must be consistent with 1 AO3

height calculated in 03.2 4.2.2.5

4.2.2.6

03.4 max 2 marks if refer to energy AO2

being made / used / produced / 4.2.2.5

created 4.2.2.6

allow reference to calories / 4.4.2.2

joules for energy 4.4.2.3

any three from: 3

• increased energy intake allow increased energy intake if

11 if more food eaten more fat / carbohydrate eaten

allow converse

allow energy taken in when you

eat

• if exercise more, more allow if exercise more,

energy is transferred / respiration / metabolism

released increases or is faster

allow converse

allow energy is transferred

during exercise

do not accept energy is burnt

during exercise

• if more energy is taken in allow if less energy is

than is transferred body transferred than is taken in body

mass increases mass increases

or or

if less energy is taken in if more energy is transferred

than is transferred body than is taken in body mass

mass decreases decreases

• if energy intake = energy

transferred body mass

stays the same

if no marks are awarded allow 1

mark for food eaten can

increase body mass and

exercise can decrease body

mass

or

allow 1 mark for if a lot of food is

eaten and little exercise is done

body mass increases

allow converse

AO /

Question Answers Mark

Spec. Ref.

Level 3: Relevant points (reasons/causes) are identified, given in

03.5 detail and logically linked to form a clear account. 5–6 AO1

4.4.2.1

Level 2: Relevant points (reasons/causes) are identified, and there 3–4 4.4.2.2

are attempts at logical linking. The resulting account is not fully

clear.

Level 1: Points are identified and stated simply, but their relevance 1–2

is not clear and there is no attempt at logical linking.

No relevant content 0

Indicative content

During exercise:

• increased breathing rate

• increased breath volume

• (to) take in more oxygen for (aerobic) respiration

• (and) exhale more carbon dioxide

• increased heart rate

• (so) increased blood flow (to muscles)

• (to) transport oxygen / glucose to respiring cells faster

• (and) increase rate of carbon dioxide removal

• glycogen converted to glucose

• insufficient oxygen supplied (during prolonged vigorous exercise)

• (so) lactic acid is formed (during anaerobic respiration)

• (and) an oxygen debt is created

• (lactic acid causes) muscles become fatigued / tired or (causes)

muscles to stop contracting efficiently

• allow reference to sweating or increased body temperature or

vasodilation (during or after exercise)

After exercise:

• heart rate remains high or heart rate slowly decreases

• continue to breathe rapidly or breathing rate slowly decreases

• (to) pay back oxygen debt

• oxygen debt is the amount of oxygen needed to break down

lactic acid

• (and to) provide more oxygen to react with the lactic acid and

remove it from cells

• (some) lactic acid transported to liver

• (lactic acid) is converted back into glucose

For Level 3 need reference to:

• changes during and after exercise

• lactic acid and its removal.

Total 14

How to answer it

Body Mass, BMI and Exercise

What this question tests

You need to recall a disease linked to being overweight, rearrange the BMI equation correctly, read a BMI chart, and explain how diet and exercise affect body mass. For the long answer, you also need to describe what happens during vigorous exercise and after exercise, including anaerobic respiration, lactic acid, and oxygen debt.

Question overview

Key topics

  • Health effects of being overweight
  • BMI equation and rearranging
  • Using a height–mass chart
  • Energy balance, diet and exercise
  • Anaerobic respiration during exercise

How marks are awarded

  • Some parts are 1 mark: one correct recall answer is enough.
  • Calculation question is multi-step: show working for method marks.
  • The 6-mark explanation rewards linked points in a clear order.

Part (a) / Question 03.1

Give one disease related to being overweight. [1 mark]

✅ Correct answers

  • Type 2 diabetes
  • Coronary heart disease / CHD
  • High blood pressure
  • Cancer
  • Depression
  • (Osteo)arthritis

Exam tip: Any one of these earns the mark.

💡 Key knowledge

The mark scheme accepts several conditions linked to obesity/overweight. The safest GCSE answers are type 2 diabetes or coronary heart disease.

❌ Common errors

  • Writing type 1 diabetes — this is not accepted.
  • Writing only obesity — the question asks for a disease.
  • Writing heart attack or heart failure — these are not accepted in the mark scheme here.

Part (b) / Question 03.2

Calculate the woman’s height from her BMI and body mass. [3 marks]

📐 Calculations: step-by-step

Formula: BMI = body mass in kg ÷ (height in m)²

  1. Substitute the values: 27 = 68.1 ÷ height²
  2. Rearrange to find height²: height² = 68.1 ÷ 27
  3. Calculate: height² = 2.52 (to 3 s.f.)
  4. Square root: height = √2.52 = 1.59 m

Final answer: 1.59 m

✅ Correct answer

Height = 1.59 m

The mark scheme allows a correctly rounded value. If a student uses 2.5 for height² in step 2, 1.58 m is also accepted.

🧠 Exam technique

  • Show the rearrangement clearly for method marks.
  • Make sure the answer is in metres, not cm.
  • Use the square root at the end — many students forget this.
  • Give a sensible rounded answer.

❌ Common errors

  • Using 27 ÷ 68.1 instead of 68.1 ÷ 27 .
  • Stopping at 2.52 without square-rooting.
  • Giving cm instead of m.
  • Rounding too early and losing accuracy.

Part (c) / Question 03.3

Which weight category describes the woman? [1 mark]

✅ Correct answer

Overweight

💡 Key knowledge

The woman’s BMI is 27, which is in the overweight range. The mark scheme says the answer must match the height calculated in 03.2.

❌ Common errors

  • Ticking healthy weight because the chart is not read carefully.
  • Using the wrong BMI or the wrong height from part (b).

Part (d) / Question 03.4

Describe how diet and exercise control body mass. [3 marks]

✅ Correct answer points

  • If more food is eaten, more energy is taken in.
  • If a person exercises more, more energy is transferred / released.
  • If energy intake is greater than energy transferred, body mass increases.
  • If energy intake is less than energy transferred, body mass decreases.
  • If energy intake = energy transferred, body mass stays the same.

💡 Key knowledge

The examiner accepts answers in terms of energy, and allows references to calories or joules. The key idea is the balance between energy in from food and energy used in exercise and respiration.

🧠 Exam technique

  • Give linked cause-and-effect statements.
  • To secure full marks, cover both sides of the balance: food intake and exercise.
  • Use comparison words like more than, less than, and same as.

❌ Common errors

  • Writing vague statements like “eat less and exercise more” without explaining why body mass changes.
  • Saying energy is “burnt” during exercise — the mark scheme does not accept that wording.
  • Forgetting that body mass stays the same when energy in equals energy out.

Part (e) / Question 03.5

Explain what happens during and after long periods of vigorous exercise. [6 marks]

💡 Key knowledge: during exercise

  • Breathing rate increases.
  • Breath volume increases.
  • More oxygen is taken in for aerobic respiration.
  • More carbon dioxide is exhaled.
  • Heart rate increases.
  • Blood flow to muscles increases.
  • Oxygen and glucose are transported to respiring cells faster.
  • If oxygen supply is insufficient, anaerobic respiration happens.
  • Lactic acid is formed.
  • Muscles may become tired or fatigued.
  • Body temperature may rise and sweating/vasodilation may help cool the body.

💡 Key knowledge: after exercise

  • Heart rate and breathing rate stay high for a while, then slowly decrease.
  • Extra oxygen is needed to pay back the oxygen debt.
  • Oxygen is used to break down lactic acid.
  • Lactic acid is transported in the blood to the liver.
  • In the liver, lactic acid is converted back into glucose.

🧠 Exam technique

  • For Level 3, give a clear, linked account.
  • Include both during and after exercise.
  • Make sure you mention lactic acid and its removal.
  • Use cause and effect: “because oxygen is insufficient, anaerobic respiration happens”.

❌ Common errors

  • Only describing increased heart rate without explaining why it happens.
  • Forgetting anaerobic respiration and lactic acid.
  • Not mentioning what happens after exercise.
  • Stating that oxygen debt is “lost oxygen” rather than extra oxygen needed to break down lactic acid.

✅ A full-mark style answer

During vigorous exercise, breathing rate and breath volume increase so more oxygen enters the body for aerobic respiration. Heart rate increases and more blood flows to the muscles, so oxygen and glucose are delivered faster and carbon dioxide is removed faster. If not enough oxygen is supplied, the muscles respire anaerobically and lactic acid is produced, which makes muscles feel tired. After exercise, heart rate and breathing rate stay high for a while and then slowly decrease. This is because oxygen debt must be repaid. Extra oxygen is needed to break down lactic acid, and some lactic acid is carried to the liver where it is converted back into glucose.

This kind of answer reaches the top level because it covers both phases of exercise and links the ideas logically.

❌ Calculation-style trap? Not here — but wording matters

There is no calculation in this part, but students often lose marks by giving isolated facts instead of a linked explanation. The examiner is looking for a sequence: more exercise → more oxygen needed → anaerobic respiration if oxygen is insufficient → lactic acid → oxygen debt → recovery after exercise.

Final revision checklist

Remember these facts

  • Type 2 diabetes is linked to being overweight.
  • BMI = mass ÷ height².
  • Height must be in metres.
  • Overweight BMI is around 25–30.
  • Exercise can increase energy use and reduce body mass.
  • Vigorous exercise can cause anaerobic respiration and lactic acid build-up.

How to secure marks

  • Use the correct scientific term.
  • Show working in calculations.
  • Link ideas together in the 6-marker.
  • Use the chart only after calculating the BMI / height correctly.

Topics

Biology · B4: Bioenergetics · B5: Homeostasis and Response

Question and mark scheme from the AQA GCSE Combined Science: Trilogy examination, Biology Paper 1 (Higher), 2020. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.