Class 6 ncert science solution chapter 8

Ncert class 6 science 

       chapter 8.

        BODY MOVEMENTS

This chapter about how are body parts move. When we walk, Run, skip, jump and move place to place. And also how different animals move .

8.1 human body and its moment.

they are different types of joint in our body to help us carry out different movement and activities:-

a). Ball and socket joints

The rounded and of one born fits into the cavity( hollow space) of the other bone called ball and socket joints. Such joint allows movement in all directions.
Example :- our shoulder  have bawl like part to which our arm is joined.

b). Pivotal joint

The joint where our neck joins the head is a pivotal joint. It allows us to bend our head forward and backward and turn the head to our right or left.

c). Hinge joints

They allow the part to move back and forth. Example - our elbow has hinge joint that allows only a back and forth movement.

d). Fixed joints

The bones cannot move at these joints, such joints are called fixed joints.
Example - joint between the upper jaw and the rest of the head which is a fixed joint.

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

Bones and cartilage from the skeleton of the human body. It gives the frame and shape to the body and helps in movement. It protects the inner organs.

How do we know  the shape of a human skeleton?
They are two ways:-
1. Buy feeling them.
2. X- ray images of body parts.

Rib cage 

 Ribs are chest bones. They are curiously bent and  join the chest bone and the backbone together to form a box this is called the Rib cage.

8.2 " GAIT OF ANIMALS"

Movement in Earthworm

Earthworm does not have bones. It has muscles which help to extend and shorten the body. During movement, the earthworm first extends the front part of the body, keeping the rear portion fixed to the ground. Then it fixes the front end and releases is the real end. It then shortens the body and pulls the rear end forward. This makes it move forward by a small distance, repeating such muscle expansion and contraction the earth worm can move through soil. It body secretes a slimy substance to help the moment.

 Movement in Snail

Snail has no bones. The thick structure of foot made of strong muscles. The the wavy motion of the foot help them to move.

  Movement in Cockroach

Cockroaches walk and climb as well as fly in the air. They have three pairs of legs. These help in walking. There are two pairs of wings attached to the breast. The breast muscles move the winds when the cockroach flies.

Movement in Birds

Birds fly in the air and walk on the ground. Some Birds like ducks and swans also swim in water.
The birds can fly because their bones are hollow and light. The bones of the hind limbs are typical for walking and perching. The the bony parts 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.

Movement in fish

Fish body is streamlined, the head and tail of the fish is smaller than the middle portion. The shape is such that water can flow around it easy and allow the fish to move in water. The Skeleton of the fish is covered with strong muscles. During swimming, muscles make the front part of the body curve to one side and the tail part swings towards the opposite side. This makes a jerk and pushes the body forward. A series of such jerks make the fish swim ahead.

How do snakes move?

Snakes have a long backbone. They have many thin muscle that connected to each other. The snake's body curves into many loops. Each loop of the snake give it a forward push by pressing and against the ground. Since its long body makes many loops and each loop give its this push, the snake moves forward very fast and not in a straight line.

       Key Words 

ncert class 6 science                  chapter 8

Important keywords of chapter 7 science class 6

Backbone - backbone is the vertebral column made of by many small bones. It present body's backside.

Ball and socket joint -The rounded and of one born fits into the cavity( hollow space) of the other bone called ball and socket joints. Such joint allows movement in all directions.

Cartilage - Some additional parts of the skeleton that are not as hard as the bones and which can be bent, are called cartilage.

Cavity - It is a hollow space of the bones where other bones fit.

Fixed joint -The bones cannot move at these joints, such joints are called fixed joints.

Gait of animals - It is the different manner of movement in animals.

Hinge joint -They allow the part to move back and forth. Example - our elbow has hinge joint that allows only a back and forth movement.

Muscle - Muscle is the soft tissue found around the bones in most of the animals. That made of by actin and myocin filaments that help in muscle contraction.

Outer skeleton - The body is covered with a hard outer skeleton. Example - in cockroach.

Pelvic bones - They enclose the portion of our body below the stomach. This is a part you sit on.

Pivotal joint -The joint where our neck joins the head is a pivotal joint. It allows us to bend our head forward and backward and turn the head to our right or left.

Rib cage -Ribs are chest bones. They are curiously bent and  join the chest bone and the backbone together to form a box this is called the Rib cage.

Shoulder bones -  The shoulder is a complex joint connecting the arm to the body. The shoulder is made up of three bones scapula, clavicle and humerus.

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

Streamlined - The head and tail are smaller than the middle portion of the body , the body tapers at both ends , this body shape is called streamlined.

 Class 6 ncert solution 

 Exercises

1. Fill in the blanks :-
a) Joints of the bones help in the ________ of the body .
b). A combination of bones and cartilage forms the _________ of the body.
c). The bones at the elbow joints by a _______ joint.
d). The contraction of the _______ pulls the bones during movement.
Ans -
a) movement
b) skeleton
c) hinge
d) muscle

2. Indicate true (T) and false (F) among the following sentences.

(a). The movement and locomotion of the 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.
Ans:-
a) False
b) false
c) false
d) True
e) True

3. Match the items in column 1 with one or more items of column 2.
___________________________________________
___Column _1_______|__Column 2 ________
   Upper jaw               | have fins in 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.
_____________________________________________
Ans:- 
Upper jaw-    is an immovable joint.
Fish -               have fins in the body, have                             a streamline body.
Ribs-               protects the heart
Snail-              show very slow movement.
Cockroach - has an outer skeleton, can                               fly in the air.

4. Answer the following question:-

(a) What is a ball and socket joint? 
Ans -The rounded and of one born fits into the cavity( hollow space) of the other bone called ball and socket joints. Such joint allows movement in all directions.
Example :- our shoulder  have bawl like part to which our arm is joined.

(b) Which are the skull bones are movable?

Ans - Only the lower jaw in skull is movable.

(c) Why can our elbow not move backward?
Ans :- Our elbow has hinge joint that allows only a back and forth movement.Due to this reason our elbow not move backward.