1. 1
   A hospital ward uses a monitoring system that continuously records a patient's core body temperature, blood glucose concentration and hydration level throughout the night, alerting staff if any of these deviate too far from normal.

   (a)

   Which of these best defines the process by which the patient's body works to keep these variables within a narrow range?

   [1 mark]

   • AHomeostasis
   • BDiffusion
   • COsmosis
   • DActive transport

   (b)

   The device detects that the patient's blood glucose concentration has risen after their evening meal. A hormone is released into the blood, which acts on the liver, causing liver cells to convert glucose into glycogen for storage. In terms of a control system, what role is the liver playing here?

   [1 mark]

   • AReceptor
   • BEffector
   • CCoordination centre
   • DStimulus

   (c)

   Using the information in the scenario, explain why it is important for the patient's body to keep body temperature, blood glucose concentration and water levels within narrow limits.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A cyclist competing in a long-distance road race is monitored by exercise scientists. As she cycles for several hours, her coach notes that halfway through the race, after eating an energy gel, her blood glucose concentration rises sharply before falling back towards normal.

   (a)

   Which gland acts as the coordination centre that monitors and controls the cyclist's blood glucose concentration?

   [1 mark]

   • AAdrenal gland
   • BThyroid gland
   • CPancreas
   • DPituitary gland

   (b)

   Which sequence correctly shows the general order in which a control system responds to a stimulus, such as the cyclist's rising blood glucose concentration?

   [1 mark]

   • AStimulus → receptor → coordination centre → effector → response
   • BStimulus → effector → coordination centre → receptor → response
   • CReceptor → stimulus → response → coordination centre → effector
   • DCoordination centre → stimulus → receptor → effector → response

   (c)

   Using the general control-system sequence, explain how a fall in the cyclist's blood glucose concentration back towards normal would be detected and corrected, referring to the receptor, coordination centre and effector involved.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A student is comparing two systems in the human body that respond to changes in internal and external conditions: the nervous system and the hormonal (endocrine) system. She has been told that both work to help maintain a stable internal environment, but that they do so in different ways.

   (a)

   Describe the three types of component present in every control system that helps maintain homeostasis, giving an example of each.

   [3 marks]

   (b)

   Explain, using ideas about homeostasis, why the human body needs both nervous and hormonal control systems rather than relying on just one.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A first responder is treating a patient found unconscious outdoors on a very cold night. The patient's body temperature, blood glucose concentration and hydration level are all found to be well outside their normal ranges, and paramedics note that the patient's usual control systems appear to have been overwhelmed by the extreme conditions.

   (a)

   Explain what is meant by homeostasis and why it is essential for maintaining normal cell and enzyme function, using this scenario to illustrate your answer.

   [6 marks]

   (b)

   Using the ideas of receptors, coordination centres and effectors, explain how the patient's control systems would normally act to restore body temperature, blood glucose concentration and water levels to normal, and suggest why these systems failed to prevent the extreme conditions described.

   [6 marks]

   Total for question 4: 12 marks

End of questions