AQA GCSE Biology Biology Paper 2 (Foundation), November 2021: Question 10

✅ Correct Answers (Any one)

• Movement / muscle contraction would release (extra) heat.
• Movement would increase body temperature.
• Movement would increase sweating.

💡 Key Knowledge

Muscles contract during movement. Muscle contraction requires ATP from cellular respiration, which is an exothermic reaction. Respiration always transfers some thermal energy into surrounding tissues and blood.

❌ Common Errors

Giving vague answers like "to keep it a fair test" or "so results are accurate". At GCSE, you must identify the exact physiological mechanism: heat release from respiration.

✅ Correct Answer

Tick: 37.4 °C

🧠 Exam Technique: Use the Graph, Not General Knowledge

Many students blindly choose 37.0 °C because textbooks often state standard body temperature as 37 °C. You must read the baseline from Figure 17 before the water is drunk (0 to 20 minutes), where the line sits exactly on 37.4 °C.

✅ Mark Scheme Breakdown

• Mark 1: Blood is cooled at the stomach / mouth.
• Mark 2: This (cooled) blood flows / circulates to the brain.

💡 Key Knowledge: Blood as a Coolant

Ice-cold water does not touch the brain directly! Instead, cold water conducts heat away from blood vessels in the mouth and stomach lining. The cooled blood is pumped through the heart and up through the carotid arteries directly to the brain.

❌ Common Errors

• Omitting the word blood (e.g. "the cold water travels up to the head" scores 0).
• Confusing temperature reduction with nerve signals (e.g. "cold impulses go to the brain" explains detection, not physical cooling).

✅ Correct Answers

• Via nerve(s) / neurone(s)
• Via (nerve) impulses / electrical signals
• Via the nervous system

🧠 Exam Technique: Fast Coordination

Thermoregulatory adjustments to skin effectors require rapid control and use electrical impulses travelling along neurones, not hormones in the blood.

❌ Common Errors

Saying "by hormones" or "through the blood". Sweat glands are activated or suppressed by the nervous system.

✅ Mark Scheme Breakdown

• Mark 1: Less sweating occurs (or less sweat evaporates).
• Mark 2: So less heat is lost from the body (or less cooling occurs / less heat is used for evaporation).

❌ Common Errors & Mark Traps

• Trap: Saying "sweating stops". Figure 18 shows the rate drops from ~3.7 to ~0.9 units, but does not reach zero. The mark scheme explicitly states: "do not accept no sweating".
• Forgetting to explain heat loss: simply stating "sweat rate decreases" only earns 1 mark. You must link evaporation of sweat to cooling.

💡 Key Concept: Evaporative Cooling

Water has a high latent heat of vaporisation. When sweat evaporates from the skin surface, it absorbs thermal energy from the blood and skin. When core temperature drops, reducing sweat output preserves body heat.

✅ Correct Answer

Tick: Dilation of blood vessels in the skin

💡 Key Knowledge: Vasodilation

During exercise, body temperature rises. The thermoregulatory centre causes arterioles supplying skin capillaries to dilate (widen). More warm, oxygenated blood flows close to the skin surface, causing the skin to look red and radiating heat into the surroundings.

❌ Classic GCSE Misconception

"Blood vessels move closer to the skin surface."
Blood vessels are fixed in anatomical position and never move through tissue! They can only change diameter (constrict or dilate).