1. 1
   A marathon runner finishes a race in hot weather having sweated heavily and drunk very little water. A doctor notices his urine sample is dark yellow and highly concentrated.

   (a)

   Which substance, apart from water and ions, is the main waste product removed from the blood by the kidneys and found in urine?

   [1 mark]

   • AUrea
   • BGlucose
   • CProtein
   • DHaemoglobin

   (b)

   Which hormone controls the amount of water reabsorbed from the collecting duct back into the blood, affecting how concentrated the runner's urine becomes?

   [1 mark]

   • ATestosterone
   • BInsulin
   • CAdrenaline
   • DADH

   (c)

   Explain why the runner's urine is more concentrated than usual after the race.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A veterinary researcher is studying kidney function in dairy cattle by examining how blood is filtered within the nephron.

   (a)

   In which part of the nephron does ultrafiltration take place?

   [1 mark]

   • ALoop of Henle
   • BBowman's capsule/glomerulus
   • CCollecting duct
   • DUreter

   (b)

   Which substance, although present in the glomerular filtrate immediately after ultrafiltration, should not normally appear in the final urine because it is selectively reabsorbed?

   [1 mark]

   • AWater
   • BUrea
   • CGlucose
   • DIons

   (c)

   Explain why glucose, although present in the glomerular filtrate, does not normally appear in the animal's urine.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A student drinks a large bottle of water in one go. Over the next hour she notices she needs to urinate frequently and produces a large volume of pale, dilute urine.

   (a)

   Describe the structures of the urinary system, from the kidneys to the outside of the body, and the role of each in producing and releasing this urine.

   [3 marks]

   (b)

   Describe the process of ultrafiltration in the Bowman's capsule, including which components of the blood pass into the filtrate and which do not.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   Medical researchers studying patients with kidney disease compare their kidney function with that of a healthy person, focusing on how a healthy nephron processes blood into urine.

   (a)

   Describe, in detail, the structure of the nephron and the stages by which it processes blood into urine, from filtration through to the formation of urine leaving the collecting duct.

   [6 marks]

   (b)

   Explain how the kidneys carry out both excretion and osmoregulation, why this is essential for maintaining a constant internal environment, and why patients whose kidneys fail may require dialysis or a transplant.

   [6 marks]

   Total for question 4: 12 marks

End of questions