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The human kidney is an organ that is able to process excretory products from human metabolism.

Concentration of urine is calculated using this formula.

\text { concentration in milliosmoles per } \mathrm{dm}^{3}=\frac{\text { amount of waste in milliosmoles }}{\text { volume in } \mathrm{dm}^{3}}

The amount of waste the kidneys produce per day is 600 milliosmoles.
The maximum concentration that the human kidneys can produce is 1400 milliosmoles per $\mathrm{dm}^{3}$ .

Calculate the minimum volume of urine that must be produced each day.
Give your answer in $\mathrm{cm}^{3}$ .
minimum volume = $\mathrm{cm}^{3}$

600 / 1400

- $0.43 \mathrm{dm}^{3}=$

- 430

one mark for 600 /1400 or one mark for 0.43/ eq

full marks for correct answer with no working

allow 429 / 428.57 or 428.6 / eq

Edexcel IGCSE Biology 3b Change the Subject of an Equation Topic Practice

3B Change the subject of an equation question 1