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NCERT Solutions of Science for Class 6th Lesson- 8 “ BODY MOVEMENTS ”

TEXTUAL QUESTIONS

Q.1- Fill in the blanks-

(a) Joints of 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.

Ans- (a) movement

(b) skeleton

(c) hinge

(d) muscles

Q.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 forearm has two bones. ( )

(e) Cockroaches have an outer skeleton. ( )

Ans- (a) False

(b) False

(c) False

(d) True

(e) True

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

COLUMN ICOLUMN II
(A) Upper jaw(i) have fins on the body
(B) Fish(ii) has an outer skeleton
(C) Ribs(iii) can fly in the air
(D) Snail(iv) is an immovable joint
(E) Cockroach(v) protect the heart
(vi) shows very slow movement
(vii) have a streamlined body

Ans-

COLUMN ICOLUMN II
(A) Upper jaw(iv) is an immovable joint
(B) Fish(i) have fins on the body
(ii) have a streamlined body
(C) Ribs(v) protect the heart
(D) Snail(ii) has an outer skeleton
(vi) shows very slow movement
(E) Cockroach (ii) has an outer skeleton
(iii) can fly in the air.

Q.4- Answer the following :

(a) What is a ball and a socket joint?

(b) Which of the skull bones are movable?

(c) Why can our elbow not move backwards?

Ans- (a) The rounded end of one bone fits into the cavity (hollow space) of other bone to form ball and socket joint. This joint allows movements in all directions.

(b) The lower jaw of the skull bones is movable.

(c) Our elbow cannot move backwards because there is a hinge joint, which allows only the back and forth movement.

CHAPTER AT A GLANCE

  • Bones and cartilage form the skeleton of the human body. It gives the frame and shape to the body and helps in movements. It protects the inner organs.
  • The human skeleton comprises the skull, the backbone, and the bones of hands and legs.
  • The bones are moved by alternate contractions and relaxations of two sets of muscles.
  • The bone joints are of various kinds depending upon the nature of joints and direction of movement they allow.
  • Strong muscles and light bones work together to help the birds fly. They fly by flapping their wings.
  • Fish swim by forming loops alternately on two sides of the body.
  • Snake slither on the ground by looping sideways. A large number of bones and associated muscles push the body forward.
  • The body and legs of cockroaches have hard coverings forming an outer skeleton. The muscles of the breast connected with three pairs of legs and two pairs of wings help the cockroach to walk and fly.
  • Earthworms move by alternate extension and contraction of body muscles. Tiny bristles on the underside of the body help in gripping the ground.
  • Snails move with the help of a muscular foot.

FAQs related to Body Movements

Q. What is a joint?

Ans- The place where two parts of our body seem to be joined is called a joint. We are able to bend or rotate our body at a joint.

Q. What is a pivotal joint?

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Ans- The joint where our neck joins the head is called pivotal joint.

Q. Where is ball and socket joint found?

Ans- Ball and socket joint is found in the shoulder.

Q. Where is hinge joint found?

Ans- Hinge joint is found in the elbows and knees.

Q. What is a fixed joint?

Ans- The joint where the bones cannot move is called fixed joint. Example- bones of skull.

Q. What is skeleton?

Ans- The bones in our body form a framework to give a shape to our body. This framework is called the skeleton.

Q. What is cartilage?

Ans- The part of the skeleton which is not as hard as the bones and which can be bent easily is called cartilage. Example- upper part of the ear and the ear lobe.

Q. Name different kinds of joints and give examples also.

Ans- Different kinds of joints are-
(i) Ball and socket joint- This joint is found in our shoulders.
(ii) Pivotal joint- Joint of head and neck.
(iii) Hinge joint- Hinge joint is found in the elbows and knees.
(iv) Fixed joint- This joint is found in the skull.

Q. What is skeleton? Write it’s functions also.

Ans- All bones of our body form a framework to give a shape to our body. This framework is called the skeleton.
Functions of the skeleton-
(i) It provides shape to our body.
(ii) It protects the inner organs of our body.

Q. How are the birds able to fly?

Ans- The birds are able to fly because their body is well suited for flying. Their are air chambers in their bones due to which their bones are hollow and light. The bones of hind limbs are typical for walking and perching. The bony part of the forelimbs are modified as wings. The shoulder bones are strong. The breast bones are modified to hold muscles of flight which are used to move the wings up and down.

Q. How is the shape of a fish helpful in swimming?

Ans- The body of the fish is streamlined due to which the water can flow around it easily and allow the fish to move in water. During swimming, the muscles make the front part of the body curve to one side and the tail part swings towards the opposite sides. A series of such jerks make the fish swim ahead. This is helped by the fins of the tail.