NCERT TEXT BOOK EXERCISES
Q1. Fill in the blanks :
(a) Joints of bones help in the _________ of body.
(b) A combination of bones and cartilages forms the _________ of the body.
(c) Bones at the elbow are joined by a _________ joint.
(d) The contraction of the _________ pulls the bones during movement.
Ans. (a) Joints of bones help in the movement of body.
(b) A combination of bones and cartilages forms the skeleton of the body.
(c) Bones at the elbow are joined by a hinge joint.
(d) The contraction of the muscle pulls the bones during movement.
Q2. Indicate true (T) or false (F) for the following sentences.
(a) Movement and locomotion of all animals is exactly the same. ( )
(b) Cartilages are harder than bones. ( )
(c) Finger bones do not have joints. ( )
(d) The fore arm has two bones. ( )
(e) Cockroaches have an outer skeleton. ( )
Ans. (a) Movement and locomotion of all animals is exactly the same. (False)
(b) Cartilages are harder than bones. (False)
(c) Finger bones do not have joints. (False)
(d) The fore arm has two bones. (True)
(e) Cockroaches have an outer skeleton. (True)
Q3. Match the items in Column I with one or more items in Column II.
|Column I||Column II|
|Upper jaw||have fins on the body|
|Fishes||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|
|Column I||Column II|
|Upper jaw||is an immovable joint|
|Fishes||have a streamlined body; have fins on the body|
|Ribs||protect the heart|
|Snail||shows very slow movement|
|Cockroach||has an outer skeleton; can fly in the air|
Q4. 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 ?
Ans. (a) Ball and socket joint is a movable joint. It consists of a bone that has a round head, which fits into a cup like depression of another bone. This helps the bone to rotate freely. Examples of such joints are hip and shoulder joints.
(b) Mandible bone which forms the lower jaw is the only skull bone that is movable.
(c) The elbow has a hinge joint. This type of a joint allows the movement in one plane only. Therefore, our elbow cannot move backwards.