CAIE A-Level Biology A2 14.1.6 Urine Formation Questions

Explain urine formation by ultrafiltration, selective reabsorption and secretion using evidence from each question and mark scheme.

Exam points

Explain urine formation by ultrafiltration, selective reabsorption and secretion.

[Maximum number: 2]

The main component of the glomerular filtrate formed in the Bowman's capsule is water. Most of this water is reabsorbed as the filtrate passes along the nephron.
- $180 \mathrm{dm}^{3}$ of water forms part of the glomerular filtrate each day.
- $1.4 \mathrm{dm}^{3}$ of water leaves the body in urine each day.

Calculate the percentage of water in the glomerular filtrate that is reabsorbed as the glomerular filtrate passes along the nephron.

Show your working and give your answer to one decimal place.

Calculation:
$\frac{180 - 1.4}{180} \times 100$
or
$\frac{178.6}{180} \times 100$

Answer:
$99.2\%$

\frac{180 - 1.4}{180} \times 100 = 99.2\%

All question bank results loaded

CAIE A-Level Biology A2 14.1.6 Urine Formation Questions question 1