Summative Practice 14 – Question 8 & 9 (Form 4 Biology Textbook Exercise and Answer)

Question 8:
Figure 4 shows a human movement.

Based on Figure 4, describe how muscles, bones, tendons, ligaments and joints enable the above movement to happen.

• The big and long femur adds strength to support body weight.

• Tendon connects muscles to bones.

• Tendon is tough and inelastic.

• Ligament supports joints for movement.

• The hinge joint at the knee, and the balland-socket joint at the pelvic girdle produce movements.

• The quadriceps femoris and the biceps femoris are antagonistic muscles.

• When the quadriceps femoris or the extensor muscle contracts and the biceps femoris relaxes, the leg is straightened.

• When the biceps femoris contracts and the quadriceps relaxes, the leg is bent.

• When the calf muscle contracts, the heel is lifted.

• At the same time, the foot pushes downwards and backwards.

• The repetitive contraction and relaxation produces movements.

Question 9:
Describe how the earthworm and fish skeletal systems are adapted for locomotion in their respective habitats.

Locomotion of an earthworm
• Earthworms have a hydrostatic skeleton.
• Earthworms move with the aid of hydrostatic pressure changes in the body.
• The circular muscles contract and the longitudinal muscles relax antagonistically.
• This causes the hydrostatic pressure to be transferred from the anterior to the posterior.

Locomotion of a fish
• Possesses endoskeleton
• The fish bone provides surface for muscle attachment.
• The left myotome contracts and the right myotome relaxes antagonistically.
• The tail moves to the left and right producing a push forward.

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