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WAEC Biology 2005 Question 19

Question 19

Support and Movement

Which of the following statements is true about movement of the forearm? In

  1. A.bending the arm, the biceps relax and the triceps contract
  2. B.bending the arm, the biceps contract and the triceps relax
  3. C.straightening the arm the biceps contract and the triceps relax
  4. D.straightening the arm, both biceps and triceps contract
Show the answer and explanation

Answer: B (bending the arm, the biceps contract and the triceps relax)

Explanation

The biceps and triceps are antagonistic: the biceps contracts (triceps relaxes) to bend the arm, and the reverse straightens it.