Muscles are arranged around joints in pairs. One muscle contracts to bend a limb at a joint, and the other contracts to straighten it. [Figure 5.1]

1. (a)(i)State the term for muscles that act in this way[1]
2. (a)(ii)Name the muscle in your arm that contracts to move your hand away from your nose after smelling a flower.[1]
3. (b)(i)Using the letters in Fig. 5.1, identify the two muscles that contract to move the leg off the ground from position R to position S. and[2]
4. (b)(ii)State what happens to the other muscles in Fig. 5.1 during this action.[1]
5. (c)Describe how a similar arrangement of muscles in the eye helps vision in dim light.[3]

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