SCIENCE CHAPTER 8 BODY MOVEMENTS TEXTUAL ANSWERS

 

CHAPTER 8

BODY MOVEMENTS

Textual Question Answer:

 

1 Choose the correct option.

a. Which of the following is a slightly movable joint?

i. Joints between wrist bones                                     ii. Knee joint

iii. Joints between vertebrae                         iv. Shoulder joint

b. Which of the following is a specialised organ found in a cockroach?

i. Setae                                                            ii. Cerci

iii. Scales                                                         iv. Swim bladder

c. Which of the following animals is a vertebrate?

i. Snake                                                                       ii. Snail

iii. Earthworm                                                             iv. Cockroach

d. Which of the following joints is a ball and socket joint?

i. Elbow joint                                                   ii. Neck joint

iii. Knee joint                                                   iv. Shoulder joint

e. Birds can fly because they have .

i. a streamlined body                                      ii. hollow bones

iii. wings and feathers                                    iv. all of these

 

2. Fill in the blanks.

a. The act of moving from one place to another is known as locomotion .

b. The bristles present on the underside of an earthworm are called as Setae.

c. The eyes of a snail are located on the bigger (upper) tentacles.

d. The joints between the parts of a finger are  hinge joints.

 

3. State whether the following statements are True (T) or False (F).

a. Movement is brought about by the contraction and relaxation of muscles.  (T)

b. A snail moves with the help of setae.                                                                        (T)   

c. A pivot joint allows us to move our arms.                                                                  (F)   

d. The rib cage protects the lungs and the heart.                                                          (T)

e. Outer skeleton is present in cockroach.                                                                       (T)

f. Our skull has movable joints.                                                                                        (F)

g. Cartilages are harder than bones.                                                                               (F)  

4. Answer the following questions in brief.

a. Name the parts of the human skeleton.

ANS: The main parts of the human skeleton are the skull, the spine or the backbone, the rib cage, the limbs, the shoulder bones and the pelvic bones.

b. Explain the importance of a swim bladder in a fish.

ANS: A swim bladder in a fish can be filled with air or emptied to help them move up and down in water.

c. Name the different features of the body of a bird that help in flying.

ANS:  The following features help the birds to fly;

Ø  The bodies of birds are streamlined, which reduces the resistance of air while flying.

Ø  Birds have light and hollow bones.

Ø  The forelimbs in birds are modified into wings.

Ø  The wings are covered with feathers which help in flying.

Ø  Birds have strong shoulder bones and chest muscles to support the movement of wings during flight.

d. Explain the role of muscles in movement of bones.

ANS: Muscles always work in pairs. The shortening of muscle fibres is known as contraction and the lengthening of muscle fibres is known as relaxation. One end of a muscle is attached to a movable bone and another is attached to a fixed bone. When a muscle contracts, the movable bone is pulled with the muscle. Hence, the alternate contraction and relaxation of the muscles brings about movement of bones.

e. Differentiate between a invertebrate and an vertebrate.

Invertebrates	Vertebrates
Invertebrates do not possess a backbone not an internal skeleton	Vertebrates possess a backbone and an internal skeleton.
Invertebrates have an exoskeleton	Vertebrates do not possess an exoskeleton.
examples of invertebrate animals are earthworms, snails and insects such as a cockroach.	examples of vertebrate animals are fish, snakes, birds and men.

 

5 Define the following.

a. Backbone: The long bony structure that runs down the centre of back, from the base of the skull to the lower back is known as the backbone.

b. Movement and locomotion: Animals that perform movements without shifting from one place is called movement & the act of moving from one place to another is known as locomotion

c. Gliding Joint: A type of joint where flat bones glide over each other to permit movements is known as a gliding joint.

d. Fixed Joint: The joints that are immovable are called fixed joints.

6. Answer the following questions in detail.

a. What are the different types of joints present in the human body?

ANS: The places where two or more bones come together are called joints.

On the basis of the freedom of movement allowed by joints, we can classify joints as:

• Immovable or fixed joints such as the joints between skull bones

• Slightly movable joints such as the joints between the vertebrae

• Freely movable joints such as

1.     Ball and socket joints

2.     Pivotal joints

3.     Hinge joints

4.     Fixed joints

5.     Gliding joints

b. How does a snail move?

ANS: The foot produces wave-like movements which propels the body of the snail forward. The foot secretes a slimy substance mucous that avoids friction and even helps to move over a sharp objects without getting cut. With its muscular foot and mucus, the snail can easily glide over smooth or rough surfaces & can move vertically and even upside-down. 

c. What is X-ray imaging? What are the uses of an X-ray image?

ANS: X-ray imaging are radiations which can pass through skin and soft tissues but cannot

pass through bones, hence bones can be clearly seen.

Uses of an X-ray image: An X-ray images can be used to study bones and find out if a bone is fractured or not so the doctor would immediately start with the treatment.

7. HOTS (Higher Order Thinking Skills)

a. Abhay is running really fast. What are the different types of joints that

are helping Abhay run?

ANS: The different types of joints that are helping Abhay run are Ball-andsocket joint and Gliding joint

b. How does spending time in sunlight improve bone growth and development?

ANS: Sunlight helps the body to make its own vitamin D, which is important for strong bones 

 

c. Imagine we had a single long bone as our backbone, instead of small bones. Would

movement have been possible?

ANS: No, if we did not have small bones we would not be able to bend forward, backward and also allows us to twist.

 

8. Complete the following table:

CRITERIA
Name of  th      e joint Na	Ball and Socket Joint	Gliding joint	Hinge joint	Pivot joint
Direction of movement	variety of movements like swing, flap and rotate	to move a little in many directions	only in one direction (back and forth movement)	move from side to side & also forward and backward
Loca         joint	shoulder joint, hip joint	Joints between the wrist & ankle bones	The elbow and the knee joints, joints between the parts of a finger	Joints in our neck (between the skull and the spine)