1. 1
   Before breakfast, a student's blood glucose concentration was 4.5 mmol/dm³. One hour after eating a bowl of cereal, it had risen to 7.2 mmol/dm³, before returning to a normal level by the time of her next meal.

   (a)

   Which organ produces the hormone responsible for lowering her blood glucose concentration back to normal after this meal?

   [1 mark]

   • APancreas
   • BLiver
   • CThyroid gland
   • DPituitary gland

   (b)

   Which hormone causes the student's blood glucose concentration to fall back towards normal after her breakfast?

   [1 mark]

   • AGlucagon
   • BInsulin
   • CAdrenaline
   • DThyroxine

   (c)

   Explain how insulin causes the student's blood glucose concentration to decrease after her breakfast.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   During a run lasting over two hours, a runner's blood glucose concentration fell below normal because his muscles were using glucose rapidly for respiration. His pancreas responded by releasing a hormone that raised his blood glucose concentration back towards normal.

   (a)

   What is the name of the hormone released by the pancreas in this situation?

   [1 mark]

   • AInsulin
   • BADH
   • COestrogen
   • DGlucagon

   (b)

   Which stored substance is converted into glucose in the runner's liver as his blood glucose concentration is raised back towards normal?

   [1 mark]

   • AStarch
   • BCellulose
   • CGlycogen
   • DUrea

   (c)

   Explain why the pancreas's response to the runner's falling blood glucose concentration is described as negative feedback.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   Two patients attend a clinic. Patient X was diagnosed as a teenager; blood tests show his pancreas produces very little insulin, and he requires regular insulin injections to control his blood glucose concentration. Patient Y was diagnosed in her fifties; blood tests show her pancreas produces normal, even higher than normal, amounts of insulin, but her body cells no longer respond properly to it. She is overweight and manages her condition with a controlled diet and exercise.

   (a)

   Identify which patient has Type 1 diabetes and which has Type 2 diabetes, and explain the underlying cause of each patient's condition.

   [3 marks]

   (b)

   Explain why Patient Y's doctor recommended a carbohydrate-controlled diet and regular exercise rather than insulin injections, and suggest one risk factor that may have contributed to her condition.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A student is studying how the human body keeps blood glucose concentration within a narrow range despite eating meals of very different sizes and going for long periods without food overnight. She investigates the role of the pancreas, insulin and glucagon in this process.

   (a)

   Explain, in detail, how the pancreas monitors and controls blood glucose concentration when it rises above normal after a large meal, including the role of the liver.

   [6 marks]

   (b)

   Explain, in detail, how the pancreas monitors and controls blood glucose concentration when it falls below normal during a long period without food, and explain how insulin and glucagon work together as a negative feedback system to maintain a stable blood glucose concentration.

   [6 marks]

   Total for question 4: 12 marks

End of questions