CAIE A Level Biology 9700 · Control and coordination
An electron micrograph of a relaxed sarcomere from striated muscle shows a broad I-band and a prominent H-zone. Describe the sequence of events during contraction of this sarcomere according to the sliding filament model, and explain the roles of calcium ions, troponin, tropomyosin, and ATP.
5 marks, so the mark scheme is looking for about 5 separate creditworthy points. Making the same point twice in different words earns it once.
Describe means: Say what happens or what something is like, in order and with detail. You are not being asked why. If there is data, quote it: name the trend, then give figures with units at the points where it changes.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.