Scientists investigate the effect of water intake on two groups of healthy adults. Each adult in group A drinks 600 cm3 of water and each adult in group B drinks 200 cm3 of water.
The table shows the mean urine measurements for each group during a collection period.
| Group | Collection time in min\mathrm{min}min | Urine volume in cm3\mathrm{cm^3}cm3 | Urea concentration in g dm−3\mathrm{g\,dm^{-3}}gdm−3 |
|---|---|---|---|
| A | 45 | 270 | 2.4 |
| B | 30 | 30 | 14.4 |
Use mass=concentration×volume\mathrm{mass}=\mathrm{concentration}\times\mathrm{volume}mass=concentration×volume, with volume in dm3\mathrm{dm^3}dm3.
Calculate the mean rate of urea excretion for each group.
Give your answers in g min−1\mathrm{g\,min^{-1}}gmin−1.
Explain which group is likely to have had the higher concentration of ADH in the blood. Use the data and your answer to part (a).
94 exam-style questions on Edexcel GCSE Biology 7.4 Blood glucose and the urinary system, covering 7.4.1 Insulin and blood glucose control, 7.4.2 Glucagon and blood glucose regulation, 7.4.3 Type 1 and type 2 diabetes, 7.4.4 Structure of the urinary system, 7.4.5 Structure and function of the nephron, 7.4.6 ADH and water regulation, 7.4.7 Treatments for kidney failure, and 7.4.8 Production of urea in the liver. Each one has a worked solution and a mark scheme showing where the marks go.