NCERT Solutions for Class 6th: Ch 8 Body Movements Science
Page No: 77
Exercises
1. Fill in the blanks:(a) Joints of the bones help in the ____________ of the body.
(b) A combination of bones and cartilages forms the ___________ of the body.
(c) The bones at the elbow are joined by a ______________________ joint.
(d) The contraction of the _____________ pulls the bones during movement.
Answer
(b) A combination of bones and cartilages forms the skeleton of the body.
(c) The bones at the elbow are joined by a hinge joint.
(d) The contraction of the muscles pulls the bones during movement.
2. Indicate true (T) and false (F) among the following sentences.
(a) The movement and locomotion of all animals is exactly the same. ( )
(b) The cartilages are harder than bones. ( )
(c) The finger bones do not have joints. ( )
(d) The fore arm has two bones. ( )
(e) Cockroaches have an outer skeleton. ( )
Answer
(a) False
(b) False
(c) False
(d) True
(e) True
Page No. 78
3. Match the items in Column I with one or more items of Column II.
| Column I | Column II |
| Upper jaw | have fins on the body. |
| Fish | has an outer skeleton. |
| Ribs | can fly in the air. |
| Snail | is an immovable joint. |
| Cockroach | protect the heart. |
| - | shows very slow movement. |
| - | have a streamlined body. |
Answer
| Column I | Column II |
| Upper jaw | is an immovable joint. |
| Fish | have fins on the body, have a streamlined body. |
| Ribs | protect the heart. |
| Snail | shows very slow movement. |
| Cockroach | has an outer skeleton, can fly in the air. |
4. Answer the following:
(a) What is a ball and socket joint?
(b) Which of the skull bones are movable?
(c) Why can our elbow not move backwards?
Answer
(a) In a ball and socket joint, the rounded end of one bone fits into the cavity (hollow space) of the other bone. It can allows movement in all directions.
(b) Lower jaw bone (Mandible bone) is the only movable bone in skull bone.
(c) Elbow joint has hinge joint. This joint allows movement in a plane only and hence it is not able to move backwards.
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