1. 1
   A runner is taking part in a marathon on a hot day. As the race goes on, her core body temperature rises above normal. Observers notice that her skin becomes flushed (red) and covered in sweat.

   (a)

   Which structure monitors and controls body temperature by responding to the temperature of blood flowing through it?

   [1 mark]

   • Athe pituitary gland
   • Bthe thermoregulatory centre in the brain
   • Cthe spinal cord
   • Dthe pancreas

   (b)

   As the runner's core body temperature rises during the race, what happens to the blood vessels supplying her skin capillaries?

   [1 mark]

   • AThey constrict, reducing blood flow to the skin
   • BThey remain unchanged regardless of body temperature
   • CThey close completely, stopping all blood flow to the skin
   • DThey dilate, increasing blood flow to the skin

   (c)

   Explain how sweating helps to cool the runner's body.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A hiker is caught outside in freezing winter weather without a warm coat. After twenty minutes, an observer notices that the hiker's skin has become very pale and the hiker has started to shake uncontrollably.

   (a)

   When core body temperature is too low, what happens to the blood vessels supplying the skin capillaries?

   [1 mark]

   • AThey dilate, increasing blood flow to the skin
   • BThey dilate, decreasing blood flow to the skin
   • CThey constrict, reducing blood flow to the skin
   • DThey constrict, increasing blood flow to the skin

   (b)

   What is the main effect of the hiker's muscles contracting rapidly (shivering)?

   [1 mark]

   • AIt increases the rate of respiration in the muscles, transferring more energy to warm the body
   • BIt increases the rate of sweating, cooling the body further
   • CIt causes blood vessels in the skin to dilate, warming the skin surface
   • DIt reduces the hiker's core body temperature further

   (c)

   Besides shivering, state two changes that would be happening in the hiker's skin to help reduce heat loss from his body.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A student investigates how water temperature affects blood flow to the skin. She places one hand in a bowl of water at 10°C and keeps her other hand at room temperature (20°C) for five minutes. She then measures the skin temperature of each hand using a sensor placed on the back of each hand. The hand placed in the cold water has a skin temperature of 18°C, while the hand kept at room temperature has a skin temperature of 31°C.

   (a)

   Use your knowledge of thermoregulation to explain why the skin temperature of the hand in the cold water (18°C) is lower than the skin temperature of the hand kept at room temperature (31°C).

   [3 marks]

   (b)

   Predict what would happen to the skin temperature of the hand in the cold water if the student kept her hand in the water for a further ten minutes, and explain your answer in terms of the mechanism involved.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A doctor is investigating a patient with a bacterial infection. The patient's core body temperature has risen from a normal value of 37°C to 39.5°C, and the patient reports feeling hot, with flushed, sweaty skin. The doctor treats the patient with medicine and monitors how their body temperature changes over the following six hours.

   (a)

   Explain, using your knowledge of thermoregulation, the changes you would expect to see in the patient's skin while their core body temperature is raised above normal at 39.5°C.

   [6 marks]

   (b)

   The doctor wants to investigate how effective a cooling treatment (such as a cool, damp cloth placed on the skin) is at reducing a fever. Describe a suitable method the doctor's team could use to investigate this in a group of patients with a fever, and evaluate one factor that should be controlled to make the results valid.

   [6 marks]

   Total for question 4: 12 marks

End of questions