Neco 2020 Biology Question 6

Practice essay / theory question 6 from the 2020 Neco Biology examination. This question covers excretion, kidney, nephron .

Neco 2020 Biology Essay / Theory

Topics: excretion kidney nephron

Question 6 NECO • 2020 • BIOLOGY • essay

The diagram shows a cross‑section of a human nephron, the functional unit of the kidney, with the parts labelled as follows: BC (Bowman's capsule), G (Glomerulus), PCT (Proximal Convoluted Tubule), DL (Descending Limb of the Loop of Henle), AL (Ascending Limb of the Loop of Henle), DCT (Distal Convoluted Tubule), CD (Collecting Duct) and PC (Peritubular Capillaries).

Question Parts

( a )

Describe the complete pathway that the filtrate follows from its entry into the nephron until it reaches the collecting duct, naming each structure it passes through.

( b )

Explain the specific role of the descending limb and the ascending limb of the loop of Henle in the concentration of urine, indicating the type of transport that predominates in each segment.

( c )

If the glomerular filtration rate (GFR) is 120 mL min⁻¹ and 65 % of the filtrate is re‑absorbed in the proximal convoluted tubule, 15 % in the loop of Henle and 10 % in the distal convoluted tubule, calculate the volume of urine (in mL) that reaches the collecting duct each minute.

( d )

The hormone antidiuretic hormone (ADH) increases the water‑permeability of the collecting duct. Discuss how ADH modifies the final urine volume and concentration, linking your explanation to the structures shown in the diagram.

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About This Question

This is Neco 2020 Biology Question 6. It is one of the essay questions from the 2020 Neco Biology examination.

The question covers excretion, kidney, nephron .

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