Gce Model Questions Vol1 2023 Biology Question 6

Practice essay / theory question 6 from the 2023 Gce Model Questions Vol1 Biology examination. This question covers Excretion .

Gce Model Questions Vol1 2023 Biology Essay / Theory
Topic: Excretion
Question 6 GCE_MODEL_QUESTIONS_VOL1 • 2023 • BIOLOGY • essay

A laboratory rat is fed a high‑protein diet for four weeks. Blood samples are taken before and after administration of a new diuretic drug. The following values are recorded: | Parameter | Before drug (control) | After drug (treated) | |--------------------------|-----------------------|----------------------| | Blood urea nitrogen (BUN) (mg dL⁻¹) | 18 | 30 | | Serum creatinine (µmol L⁻¹) | 85 | 120 | | Urine volume (mL day⁻¹) | 25 | 180 | Answer the questions that follow, using the data where appropriate:

Question Parts

( a )
Describe the structure of the mammalian nephron, indicating the function of each major segment (glomerulus, proximal tubule, loop of Henle, distal tubule, collecting duct) in the formation of urine.
( b )
Using the data provided, evaluate the effect of the diuretic drug on kidney function. Discuss what the changes in BUN, serum creatinine and urine volume indicate about glomerular filtration rate (GFR) and tubular handling of solutes.
( c )
Explain how antidiuretic hormone (ADH) modifies water reabsorption in the collecting duct. Predict the likely urine osmolality of the rat under (i) normal hydration and (ii) severe dehydration, and justify your predictions.

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About This Question

This is Gce Model Questions Vol1 2023 Biology Question 6. It is one of the essay questions from the 2023 Gce Model Questions Vol1 Biology examination.

The question covers Excretion .

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