Urea is a waste product made in the liver. Urea passes out of liver cells into the blood plasma. It is then carried to the kidneys, where it is removed from the blood.
Name the process by which urea passes out of a liver cell into the blood plasma.
Explain how the concentrations of urea inside a liver cell and in the blood plasma allow urea to leave the cell.
A person's kidneys stop working, so urea is no longer removed from their blood. Suggest and explain the effect this has on the rate at which urea leaves their liver cells.
140 exam-style questions on AQA GCSE Biology 1.3 Transport in cells, covering 1.3.1 Diffusion, 1.3.2 Osmosis, and 1.3.3 Active transport. Each one has a worked solution and a mark scheme showing where the marks go.