Control and coordination in mammals — practice question

Fig. 8.1 shows a transmission electron micrograph of striated muscle. On Fig. 8.1: • use the letter P with a label line to indicate a region containing only actin • use the letter Q with a label line to indicate a region containing only myosin • use the letter R with a label line to indicate a region containing both actin and myosin.

The sliding filament model explains contraction in striated muscle. Outline the role of the proteins troponin and tropomyosin in the sliding filament model.

After muscles have been working for a long period, their contraction may become less effective. This is called muscle fatigue. Suggest why muscles may become fatigued.