A sports clinic uses Fig. 1 to explain why a swimmer bends the arm during a stroke. The diagram shows two muscles attached to bones on opposite sides of the...
Question 1 Report
A sports clinic uses Fig. 1 to explain why a swimmer bends the arm during a stroke. The diagram shows two muscles attached to bones on opposite sides of the elbow. The forearm is initially straight. Muscle A is stimulated by a small electrical pulse and the movement is observed. The boxes show the attachments of each muscle to the skeleton.
(a) Name the type of muscle shown in Fig. 1. [1]
(b) Describe the movement of the forearm when muscle A contracts. [2]
(c) Explain why muscle B must relax as muscle A contracts. [2]
(d) Complete this statement: muscles A and B form an __________ pair. [1]
(e) State one feature of a muscle cell that allows it to release much energy. [1]
Answer Details
(a) The muscles shown are skeletal, or voluntary, muscles. [1]
(b) When A contracts, the forearm bends at the elbow. The elbow angle decreases and the forearm moves upwards. [2]
(c) Muscles can pull but cannot push. Therefore B must relax when A contracts; if B stayed contracted, it would oppose the bending movement. [2]
(d) A and B form an antagonistic pair. [1]
(e) Muscle cells contain many mitochondria, enabling substantial energy release by respiration. [1]
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