AQA GCSE Biology Biology Paper 2 (Higher), June 2022: Question 8

13 marks · Standard Demand difficulty · Short Answer

Analyse body temperature control and thermoregulation in echidnas and humans, including explanations of vasodilation, metabolic energy during hibernation, and calculating sweat volume.

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Question

Question text

08 An echidna is a mammal that lives in Australia.

Figure 10 shows an echidna.

Figure 10

Figure 11 shows how the body temperature of the echidna varies in warm weather

and in cold weather.

Figure 11

Figure 12 shows how human body temperature varies.

Figure 12

08.1 Compare the variation in body temperature of the echidna in warm weather with the

variation in body temperature of the human.

*30* Use data from Figure 11 and Figure 12.

[2 marks]

In the cold winter months, the echidna hibernates.

During hibernation:

• the echidna’s body temperature decreases to below 5 °C

• the echidna sleeps for up to 17 days at a time

• the echidna’s rate of metabolism slows down.

08.2 Explain why the decrease in body temperature is an advantage to the echidna

during hibernation.

[2 marks]

08.3 During hibernation the echidna wakes up several times.

Each time the echidna wakes up it becomes active and its body temperature

increases to over 30 °C.

Explain why the echidna has a higher body temperature when it is active.

[2 marks]

08.4 An echidna can dilate and constrict blood vessels in its skin.

Explain how the dilation of blood vessels in the skin can help to decrease

body temperature.

[3 marks]

An athlete trained in a hot climate.

The athlete lost a large volume of water each day in sweat.

08.5 The athlete’s energy intake each day from food was 20 000 kJ.

Evaporation of 1 cm3 of sweat requires 2.5 kJ of energy.

40% of the athlete’s daily energy intake was used to evaporate sweat.

Calculate the volume of sweat the athlete lost each day.

*32* Give your answer in dm3

1 dm3 = 1 000 cm3

[3 marks]

Volume of sweat lost in one day = dm3

08.6 Suggest why the athlete was advised to take salt tablets each day.

[1 mark]

Mark scheme

Show the mark scheme

Question 8

AO /

Question Answers Extra information Mark

Spec. Ref.

08.1 echidna: 27 to 35 or by 8 (°C) allow a tolerance of ± 0.5 (°C) 1 AO3

and 4.5.1

human: 36.2 to 37.2 or by 1 (°C) allow a tolerance of ± 0.1 (°C) 4.5.2.4

echidna is more variable 1

human fluctuates less

allow echidna is 7 (°C) more

variable for 2 marks

allow echidna is 8 times more

variable for 2 marks

AO /

Spec. Ref.

do not accept energy produced

08.2 / made / created AO2

do not accept energy used for 4.5.2.4

respiration 4.5.3.2

4.4.2.1

loses less energy (from its body) allow loses / wastes less heat 1 4.4.2.3

(so) body energy store lasts allow glycogen / fat lasts longer 1

longer allow stored food lasts longer

lower temperature gradient

(between echidna and air) (1)

(so) loses less energy (1) allow loses less heat

less energy transferred allow less energy transferred for

maintaining (higher) body keeping warm 25

temperature (1)

(so) more energy available for allow more energy for eg heart /

processes vital for life (1) brain function

ignore metabolism

AO /

Spec. Ref.

do not accept energy produced

08.3 / made / created once only AO2

activity / movement requires 1 4.5.2.4

energy from respiration 4.4.2.1

(and) respiration / metabolism 1

releases heat (which increases

body temperature)

respiration / metabolism

releases heat (which increases

body temperature) (1)

(which) increases the rate of

chemical reactions

increases enzyme activity (1)

AO /

Spec. Ref.

08.4 more blood flow near surface (of do not accept blood vessels 1 AO1

skin) move nearer to surface of skin 4.5.2.4

more blood flow to the skin

(so) more heat / energy is lost 1

(from the blood)

cools blood which cools the ignore cools blood / body 1

body unqualified

AO /

Spec. Ref.

08.5 AO2 27

20 000 × 40 8000 1

or 4.5.2.4

100 × 2.5 2.5

3 200 (cm3)

3.2 (dm3)

allow an incorrectly calculated 1

value correctly divided by 1000

AO /

Spec. Ref.

08.6 to replace ions / salt lost (in allow named example such as 1 AO2

sweat) Na+ 4.5.2.4

allow because ions / salt lost in 4.5.3.3

sweat

allow to prevent (muscle) cramp

Total Question 8 13

How to answer it

Thermoregulation in Mammals & Heat Exchange Calculations

WHAT THIS QUESTION TESTS

This question evaluates core concepts in AQA GCSE Homeostasis and Response (Topic 5) alongside quantitative skills:

Extracting and comparing data from temperature-time graphs (AO3).
Explaining energy conservation during hibernation using thermal gradients (AO2).
Linking muscular activity, respiration (exothermic reactions), and body temperature (AO2).
Explaining the physiological mechanism of vasodilation (AO1).
Multi-step mathematical calculation involving percentages, energy transfer, and unit conversion (cm³ to dm³) (AO2).

QUESTION 08.1 • 2 MARKS

Comparing Temperature Variations (Echidna vs Human)

Data interpretation from Figure 11 and Figure 12

✅ Correct Answer

Data comparison: Echidna varies between 27 °C and 35 °C (range of 8 °C), whereas the human varies between 36.2 °C and 37.2 °C (range of 1 °C) [1 mark].
Conclusion: The echidna's body temperature is far more variable / fluctuates more (or human temperature is much more stable) [1 mark].

Examiner note: Giving an accurate quantitative comparative statement (e.g. "the echidna fluctuates 7 °C more" or "is 8 times more variable") earns both marks directly.

🧠 Exam Technique

When a question says "Compare... Use data from...":

Quote values for both organisms (maximum and minimum or calculated range).
Make a clear comparative summary word (e.g., greater, less, more variable).

❌ Common Errors

Only quoting values for the echidna and forgetting the human.
Misreading the y-axis grid on Figure 12 (each small square on the human graph is 0.1 °C).
Forgetting to include units (°C).

QUESTION 08.2 • 2 MARKS

Advantage of Decreased Body Temperature in Hibernation

Explaining energy conservation in cold weather

✅ Correct Answer (Any one pair)

Route 1 (Energy Stores):

Loses less heat / energy from its body [1 mark].
So internal energy / food / fat stores last longer [1 mark].

Route 2 (Thermal Gradient):

Smaller temperature gradient between the body and cold air [1 mark].
Reduces rate of heat loss to surroundings [1 mark].

💡 Key Knowledge

Heat loss depends on temperature differences. In cold weather, maintaining a 30 °C body in 2 °C air creates a huge gradient (ΔT = 28 °C), causing rapid heat loss. Dropping body temp to 4 °C drastically reduces this gradient, saving vital calories.

❌ Common Errors

Illegal Biology phrasing: Saying energy is "produced", "created", or "made". Energy is only transferred.
Saying "energy is used for respiration" (respiration releases energy, it doesn't consume it).

QUESTION 08.3 • 2 MARKS

Temperature Increase During Activity

Linking respiration and heat release

✅ Correct Answer

Activity / muscle movement requires energy transferred by respiration [1 mark].
Respiration is an exothermic process that releases heat (which raises body temperature) [1 mark].

💡 Key Knowledge

Respiration is not 100% efficient. During aerobic respiration:

Glucose + Oxygen → Carbon Dioxide + Water (+ Energy transferred)

A substantial portion of this energy is dissipated as thermal energy (heat) to the tissues.

❌ Common Errors

Stating "energy is created by exercise".
Failing to mention the word respiration or metabolism.

QUESTION 08.4 • 3 MARKS

Mechanism of Vasodilation

How blood vessel dilation lowers core temperature

✅ Correct Answer

More blood flows through capillaries near the surface of the skin [1 mark].
More heat / thermal energy is lost (by radiation) from the blood to the surroundings [1 mark].
This cools the blood, which circulates back to cool the internal core body [1 mark].

💡 Key Knowledge & Diagram Guide

What happens in the skin:

Arterioles leading to skin surface capillaries dilate (lumen widens as smooth muscle relaxes). Shunt vessels constrict. More blood flows directly under the epidermis, maximizing radiant heat loss.

❌ The #1 Exam Mistake in GCSE Biology

"Blood vessels move closer to the skin surface."

This is completely wrong and scores 0! Blood vessels cannot physically move location through tissues. They only widen / dilate to allow a higher volume of blood flow near the surface.

QUESTION 08.5 • 3 MARKS

Sweat Volume Calculation

Multi-step calculation with unit conversion

📐 Step-by-Step Calculation

Find energy used to evaporate sweat (40% of intake):
20 000 kJ × 0.40 = 8 000 kJ
[1 mark awarded for step 1]
Calculate volume of sweat in cm³:
Each 1 cm³ requires 2.5 kJ:

8 000 kJ ÷ 2.5 kJ/cm³ = 3 200 cm³
[1 mark awarded for step 2]
Convert cm³ to dm³:
There are 1 000 cm³ in 1 dm³:

3 200 ÷ 1 000 = 3.2 dm³
[1 mark for final converted value]

Final Answer: 3.2 dm³

🧠 Exam Technique & Units

Always check the required unit on the answer line! The question specifically demands dm³ . Leaving the answer as 3 200 loses the final mark.
Error-Carried-Forward (ecf): If you miscalculate the initial energy value, you can still gain the 3rd mark if you correctly divide your cm³ answer by 1 000.

QUESTION 08.6 • 1 MARK

Replacing Lost Solutes

Electrolyte and ion balance

✅ Correct Answer

To replace ions / salt lost in sweat (e.g., sodium ions / Na⁺) or to prevent muscle cramps [1 mark].

💡 Key Knowledge

Sweat consists of water, mineral ions (such as Na⁺ and Cl⁻), and small amounts of urea. Sweating heavily causes both water and solute deficits. Drinking plain water without replacing ions can cause osmotic imbalance in body fluids.

❌ Common Errors

Vaguely answering "to give them energy" (salts do not supply calories or energy).
Confusing salt replacement with rehydration (water replaces fluids; salt replaces ions).

Topics

Biology · B4: Bioenergetics · B5: Homeostasis and Response

Question and mark scheme from the AQA GCSE Biology examination, Biology Paper 2 (Higher), June 2022. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.