A blood vessel has a large lumen, a thin muscular wall and valves. Which statement explains one of these features?
The valves produce the pressure needed to pump blood.
The thin wall allows red blood cells to leave the vessel.
The large lumen increases resistance to flowing blood.
The valves prevent blood flowing away from the heart.
42 exam-style questions on Edexcel GCSE Biology 8.2 Blood and circulation, covering 8.2.1 Structure and function of the blood, 8.2.2 Structure of blood vessels, 8.2.3 Structure of the heart and circulatory system, and 8.2.4 Cardiac output. Each one has a worked solution and a mark scheme showing where the marks go.