1. Fill in the blanks:

a) Joints of the bones help in the ————— of the body.

Ans: Joints of the bones help in the movement of the body.

b) A combination of bones and cartilages forms the ——— of the body.

Ans: A combination of bones and cartilages forms the skeleton of the body.

c) The bones at the elbow are joined by a ——– joint.

Ans: The bones at the elbow are joined by a hinge joint.

d) The contraction of the ———- pulls the bones during movement.

Ans: 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 are exactly the same.

Ans: False because the movement and locomotion of animals depend on their body structure. So, animals with different body structures possess different modes of movement.

b) The cartilages are harder than bones.

Ans: False because they are not as hard as bones and can be bent easily.

c) The finger bones do not have joints.

Ans: False as finger bones also have joints.

d) The forearm has two bones.

Ans: True. They are the ulna and the radius.

e) Cockroaches have an outer skeleton.

Ans: True and it is known as the exoskeleton.

3. Match the items in Column I with one or more items of Column II.

Ans: The correct match of the items given in column A is as follows:

Column I	Column II
Upper jaw	is an immovable joint
Fish has	have fins on the body and have a streamlined body
Ribs	protect the heart
Snail	Shows very slow movement
Cockroach	an outer skeleton and can fly in the air

4. Answer the following:

a) What are a ball and socket joint?

Ans: The ball and socket joint is made up of two bones. One of which is rounded and the other bone forms a socket. This allows both bones to fit perfectly and allow rotary motion in every direction. This type of joint is present at the shoulders and thighs of the body.

b) Which of the skull bones is movable?

Ans: The lower jaw bone of the skull, or mandible, is the only movable bone of the skull.

c) Why can our elbows not move backwards?

Ans: Our elbow joint is a hinge joint. These joints allow movement in one plane and up to 180 degrees only. Hence, we cannot move our elbows backwards.