Formative Practice 14.3 (Form 4 Biology Textbook Exercise and Answer)

Question 1:
In your opinion, why do birds have hollow bones?

Hollow bones are light which facilitates flying.

Question 2:
Explain how the forearm is moved upwards.

When biceps contracts, the tendon transmits a pulling force produced by the contracting muscles to the arm. At the same time, triceps relaxes. As a result, the elbow bends and the arm moves up.

Question 3:
Explain the locomotion mechanism in fish.

The vertebral column of fish is flexible and moves from side to side through the contraction and relaxation of myotome, W-shaped muscle segments. When the right myotome contracts, the left relaxes and the tail is whipped to the right. On the other hand, when the left myotome contracts, the right relaxes and the tail is whipped to the left.
Waves of alternate contractions and relaxations along the myotome causes the body parts to move from side to side, pushing water backwards and sideways, thus moving the body forward.

Question 4:
Describe how a grasshopper performs a jump/leap.

Grasshoppers have long hind legs that can be folded into a Z-shape, and in this position, it functions as a jumping spring.
When the hind legs are in the Z-position, the extensor and flexor muscles are undergoing contraction.
When the extensor muscles of the hind legs contract and straighten rapidly backwards and downwards to the ground, it provides the grasshopper a lifting force that pushes it up and forward into the air.

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