CAIE A Level Biology 9700 · Transport in mammals
A student examines stained sections of a typical artery and a typical vein. The artery wall is much thicker and contains more smooth muscle and elastic fibres than the vein wall. Explain how these structural differences relate to the functions of arteries and veins, and how they contribute to the formation of tissue fluid in capillary networks.
4 marks, so the mark scheme is looking for about 4 separate creditworthy points. Making the same point twice in different words earns it once.
Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.