CAIE A Level Biology 9700 · Transport in mammals
The table shows the thickness of the chamber walls in a mammalian heart.
| Chamber | Wall thickness (mm) |
|---|---|
| Right atrium | 2 |
| Left atrium | 3 |
| Right ventricle | 5 |
| Left ventricle | 15 |
Explain how these differences in wall thickness relate to the pressure changes during the cardiac cycle and the role of the heart's conducting system in coordinating these events.
7 marks, so the mark scheme is looking for about 7 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.