Body Movements

Our body can bend, twist, walk, run and lift things because bones, joints and muscles work together. In this chapter you will learn that places where two bones meet are called joints. Ball and socket joints in the shoulder and hip allow movement in all directions, hinge joints in the elbow and knee allow back-and-forth movement, the pivotal joint in the neck lets the head turn, and fixed joints in the skull do not move. The skeleton gives the body shape and support; it includes the skull, the backbone of 33 vertebrae, the ribcage with 12 pairs of ribs, and the shoulder and pelvic bones, along with softer cartilage. Muscles move bones by contracting, and work in pairs because a muscle can only pull. The chapter then compares how animals move: the earthworm with muscles and tiny bristles, the snail with a muscular foot, the cockroach with legs and wings, birds with hollow bones, the streamlined fish with fins, and the snake with its long backbone.

Detailed Worksheet: Body Movements Section A - Definitions (10 marks) 1. What is a joint? Name the four types of joints found in the human body. (2 marks) 2. What is the skeleton? State two functions of the skeleton. (2 marks) 3. What is cartilage? Name two parts of the body where it is found. (2 marks) 4. What is meant by gait? Give two examples of gaits of different animals. (2 marks) 5. What does the term streamlined body mean? Name one animal with such a body. (2 marks) Section B - Calculations and Applications (15 marks) 6. The ribcage of a human has 12 pairs of ribs and the backbone has 33 vertebrae. (i) How many ribs are there in all? (ii) How many more vertebrae are there than ribs? (iii) The adult human skeleton has about 206 bones; what fraction of these are ribs? (3 marks) 7. Match each movement with the joint that allows it and name the joint type: (i) turning your head to look sideways (ii) bending your arm at the elbow (iii) rotating your arm in a full circle at the shoulder. (3 marks) 8. An earthworm extends the front part of its body and anchors it with bristles, then pulls the rear part forward. If each cycle moves it forward by 2 cm and it completes 6 cycles in a minute, (i) how far does it move in 1 minute? (ii) in 10 minutes? (iii) which structures help it grip the ground? (3 marks) 9. A cockroach has 3 pairs of legs and 2 pairs of wings, and a bird has 1 pair of wings and 1 pair of legs. (i) Find the total number of legs and wings of 4 cockroaches. (ii) Find the total legs and wings of 5 birds. (iii) Which body part of the bird helps in walking and perching? (3 marks) 10. A student bends his arm at the elbow and then straightens it. (i) Which muscle contracts when the arm bends? (ii) Which muscle contracts when the arm straightens? (iii) Why do muscles have to work in pairs? (3 marks) Section C - Diagrams (10 marks) 11. Draw a labelled diagram of the human ribcage and backbone. Label the ribs, breastbone and vertebrae, and state how the ribcage protects internal organs. (4 marks) 12. Draw a labelled diagram of a ball and socket joint and a hinge joint. State one location of each in the body. (3 marks) 13. Draw a labelled diagram of a fish showing its streamlined shape, fins and tail. Explain how the tail fin helps it change direction. (3 marks) Section D - Analysis and Higher-order Thinking (15 marks) 14. Try to bend a ruler-splint tied to your arm across the elbow. (i) Can you bend the elbow? (ii) What does this show about the elbow joint? (iii) Name the type of joint at the elbow and the type of movement it allows. (iv) Why can you rotate the arm at the shoulder but not at the elbow? (5 marks) 15. Explain how a snake moves. (i) Why does a snake move in loops? (ii) How does its backbone help? (iii) Why can a snake move faster on a rough surface than on glass? (iv) Compare its movement with that of an earthworm. (5 marks) 16. Birds can fly while we cannot, even if we flap our arms. (i) Give three features of a bird's body that help in flight. (ii) Why are hollow bones useful? (iii) What role do the breastbone and flight muscles play? (iv) Why would heavy bones make flight difficult? (5 marks) Instructions: Time allowed 2 hours. Attempt all sections. Draw all diagrams neatly in pencil and label every part. Use the correct names of bones and joints.