Chapter 8
Body Movements
Exercise
I. Answer the following questions in brief:
Q. 1. What is the use of joints in our body?
Ans - A joints are the part of the body where two or more bones meet to allow movement.
Q.2. Are all joints movable? If not, given an example?
Ans - No some joints are not movable. Example - The Fixed joint of our skull,
Q. 3. Which bones do the ribs join?
Ans - The ribs join with the backbone.
Q.4. What is the use of our backbone having a large number of bones joined together instead of being a single bone?
Ans - A large number of bones in our backbone help us to bend our body.
Q.5. Name the joint present in our (i) neck (ii) knee
Ans (i) Neck: Pivot Joint (ii) Knee: Hinge Joint
Q.6. Name any two organs which the rib cage protects.
Ans (a) Heart (b) Lungs
Q.7. What are the upper parts of human ears made up of ? Where else is this substance found in our body?
Ans - The upper parts of human ears are made up of cartilage. It is also found in the joints of the body.
Q.8. What changes occur in a muscle when it contracts?
Ans - Muscular contractions are the mechanism that allows an individual, animal, or human to move its body, move the food in its digestive. The contraction shortens the muscle which moves the rigid structures, bones, to which they are attached.
Q.9. What kind of a skeleton does a snail have? Is it made of bones?
Ans - The shell on the back of snails is called the exoskeleton or external skeleton. No, it is not made of bones.
Q.10 Why does an earthworm secrete a slimy substance?
Ans - An earthworm secrete a slimy substance because it helps them to move more easily through the soil.
Q.11. What are the wings of the birds made of?
Ans - Wings of birds are made up of feathers and hollow bones which help them to fly.
Q.12. How are joints important for our body?
Ans - Joints bind the skeleton together, to give structure and allow muscles to move bones to perform certain tasks such as running, reaching and holding.
Q.13. A muscle can only pull. How, then does it help in movement?
Ans - A single muscle can only pull, it cannot push. Thus, muscles work in pairs to move the bone. When one muscle contracts, it pulls the movable bone. When another muscle of the pair pulls, it brings the bone back to its original position.
Q.14. Why does a snake not move in a straight line?
Ans - Snakes move in S-shaped loops and in a zigzag manner. Each loop of the snake gives it a forward push by pressing against the ground.
Q.15. How does an earthworm make a grip on the ground?
Ans - An earthworm has a large number of tiny bristles on the underside of its body that help it to grip the ground.
II. Give one term for each of the following:
(a) Structure formed by joining of chest bones with backbone. ribcage
(b) Shape of the fish which helps it to swim in water Streamlined body
(c) The framework of bones in our body Skeletal system
(d) The Manner of movement of an organism Gait
(e) Structure softer than the bone of which upper part of our ears is made. Cartilage
(f) Type of joint connection our neck to the head. Pivot joint
III. Fill in the blanks:
(a) The structure below the stomach which helps us to sit is pelvic bones.
(b) The joint between the upper jaw and the rest of the head is an example of fixed joint.
(c) Our muscles work in pairs.
(d) The bony part of the forelimbs of birds are modified as wings.
(e) Our forearm has two bones.
(f) A muscle can only pull, it cannot push.
IV. State whether True or False:
(a) A cockroach has four wings for flying. (True)
(b) Snails slither on the ground very slowly. (True)
(c) The body of an earthworm has the same structure as the body of a snake. (False)
(d) Fins help a fish to keep balance and direction while swimming. (True)
(e) The shell of a snail is made of bones. (False)
(f) Our backbone is made of a single flexible bone. (False)
V. Match the following:
(a) Upper part of ear - (ii) Cartilage
(b) Forelimbs - (i) Wings
(c) Neck - (vi) Pivotal joint
(d) Shoulder - (iii) Ball and socket joint
(e) Upper jaw - (iv) Fixed joint
(f) Elbow - (v) Hinge joint
VI. Select the correct alternative:
(i) How many muscles are needed to move a bone?
Ans - (b) 2
(ii) A snail walks with the help of
Ans - (c) Muscles
(iii) Which of the following have a backbone
Ans - (b) Snake
(iv) Which of these help(s) the fish to move?
Ans - (d) All of these
(v) The following figures show the models of some joints found in out body. Identify them.
Ans - (d) Ball and socket, hinge, pivotal
