Class 6 Science Chapter 8: Body Movements - NCERT Solutions

(a) Movement

It is so because, two bones are connected together with the help of joints. They helps in the movement of the body.

(b) Skeleton

Bones and cartilage are combine to form a skeleton of the body.

(c) Hinge joint

Hinge joints are those joints which moves only in one direction.

(d) Muscles

When the movement occurs, muscles pull and contraction occurs.

(a) False

It is false because locomotion means movement or displacement of entire body whereas movement is the displacement of entire body or its parts.

(b) False

It is false statement because cartilage is harder but not as bone.

(c) False

No, this statement is wrong because due to the presence of joints, our fingers can move.

(d) True

Yes, it is so because as we know that our forearm has two bones: ulna and radius.

(e) True

Yes, this statement is correct because as we know that cockroaches have outer skeleton that is made up of number of plates which helps in movement.

                                 Column I                                Column II

                              Upper jaw                                 It is an immovable joint                                                                                                                                                                      Fish                                          Have fins, have a streamlined body                                                                                                                                                  Ribs                                            Protects heart                                                                                                                                                                                 Snail                                           Show very slow movement                                                                                                                                                            Cockroach                                 Have an outer skeleton and can fly in air

Upper jaw is the skull bone. Lower jaw bone (Mandible) is the only one skull bone which is movable. Fishes have fins, have streamlined body so that they can easily swim in the water. Ribs are very hard and they protect the heart from the injuries or protects other delicate organs inside the chest. Snail shows very slow movement because movement is done by the muscular feet. Cockroaches have outer skeleton, can fly in air. This outer skeleton is made up of number of plates which helps them in the movement.

1. Ball and socket joint: It is the type of joint; one bone is like a ball and other one is like a socket, and all is fixed into the socket. This type of joint is called ball and socket joint which is found in shoulders. Such types of joints make movements easy or we can say movements occurs in all directions.
2. Mandible: It is the only skull bone which can move. It is present in the lower jaw which is movable.
3. Our elbow cannot move in the backward direction because in elbow, hinge joint is present which allows the movement of elbow only in one direction.