Paper 1, May June 2006 | Cambridge AS - A Level Biology (9700) Past Papers

Which statements about blood vessels are correct?
1 Collagen fibres in the walls of arteries and veins prevent overstretching.
2 Elastic fibres in large arteries allow stretching during ventricular systole.
3 Smooth muscle in arteries controls the distribution of blood to different parts of the body.
4 Veins have valves because their walls are thin.