A-LevelBiologyControl and coordination9700/43 · May/June 2021 · Q110 Marks
Fig. 1.1 is a diagram of a part of a sarcomere in striated muscle. [Figure 1.1]
- (a)With reference to Fig. 1.1, name A, B, C and D.[4]
- (b)When a muscle cell is stimulated, calcium ions are released from the sarcoplasmic reticulum. With reference to Fig. 1.1, describe the role of calcium ions in the contraction of the sarcomere.[4]
- (c)When a mammal dies, aerobic respiration stops. The striated muscles contract and remain contracted for a few hours after death. Suggest why the muscles remain contracted for a few hours.[2]
This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.
Mark scheme
Marking points from the official mark scheme (May/June 2021). The mark or mark type is shown in brackets.
- [1] (a) A - binding site;
- [1] (a) B - tropomyosin ;
- [1] (a) C - troponin;
- [1] (a) D - myosin head; A ATPase
- [1] (b) ref. to release from, sarcoplasmic reticulum / SR ;
- [1] (b) bind to, troponin / C;
- [1] (b) tropomyosin / B, moves / AW ; A changes shape
- [1] (b) binding site / A, exposed / AW ;
- [1] (b) myosin head / D, binds to actin or ref. to formation of cross bridge ;
- [1] (c) no/little, ATP, produced / available ;
- [1] (c) (so) no breaking of cross bridges / myosin head not released ;
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