1. 1
   A marathon runner is competing in a race through Dubai during very hot weather. As the race continues, their skin becomes flushed and covered in sweat, and their core body temperature is being carefully monitored by race medics.

   (a)

   A marathon runner competing in Dubai in very hot conditions becomes flushed and notices their skin is covered in sweat. Which response is directly causing the runner's skin to appear flushed (redder)?

   [1 mark]

   • AVasoconstriction of blood vessels near the skin surface
   • BVasodilation of blood vessels near the skin surface
   • CShivering of skeletal muscles
   • DRelease of glucagon from the pancreas

   (b)

   If this runner had instead been running in very cold conditions and their body temperature started to fall, which response would help to generate extra heat?

   [1 mark]

   • ASweating
   • BVasodilation
   • CShivering
   • DIncreased urine production

   (c)

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

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A patient visits a clinic with severe pain and is diagnosed with a kidney stone blocking part of their urinary system. The doctor also explains that the patient appears to be producing unusually large volumes of dilute urine, possibly linked to a hormone problem.

   (a)

   A patient at a clinic is diagnosed with a kidney stone that has become lodged in the tube carrying urine from the kidney to the bladder. Which structure is this?

   [1 mark]

   • AThe ureter
   • BThe renal artery
   • CThe cortex
   • DThe medulla

   (b)

   Which hormone normally controls how much water is reabsorbed by the kidney, affecting how concentrated the patient's urine is?

   [1 mark]

   • AFSH
   • BInsulin
   • CAdrenaline
   • DADH (antidiuretic hormone)

   (c)

   Explain what happens during ultrafiltration in the kidney, and state one substance that should NOT normally pass into the filtrate.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A patient with kidney failure attends hospital three times a week for dialysis treatment to remove waste products from their blood, while doctors also discuss the normal processes their kidneys would carry out if they were working properly.

   (a)

   Describe how a dialysis machine works to replace the function of the patient's kidneys.

   [3 marks]

   (b)

   Describe the processes of ultrafiltration and selective reabsorption that would normally take place in a healthy kidney, explaining why they are both necessary.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   An expedition team is trekking across a hot desert for several days, experiencing extreme heat during the day and cold at night, and going for long periods between meals as they travel between camps.

   (a)

   Explain how the hypothalamus acts as the body's 'thermostat' to control body temperature as the team's surroundings change between very hot daytime and cold desert nights.

   [6 marks]

   (b)

   Explain how the pancreas and liver work together, using insulin and glucagon, to keep the expedition team's blood glucose concentration stable during long periods without food.

   [6 marks]

   Total for question 4: 12 marks

End of questions