Samacheer Kalvi 8th Science Solutions Chapter 19 Pdf

Samacheer Kalvi 8th Science Solutions Chapter 19 Pdf

Tamilnadu Board Samacheer Kalvi 8th Science Solutions Chapter 19: Tamilnadu State Board Solution Class 8 Science Chapter 19 – Movements in Animals.

Samacheer Kalvi 8th Science Solutions Chapter 19: Overview

Board

Samacheer Kalvi
Class

8

Subject

Science
Chapter

19

Chapter Name

Movements in Animals


Samacheer Kalvi 8th Science Solutions Chapter 19 Pdf

(I) Choose the best answer.

( 1 ) Which of the following parts of our body help us in movement?

(i ) Bones    ( ii) Skin    ( iii) Muscles   (iv) organs

Choose the correct answer from the options below.

( a ) (i) and (iii)                 (b) (ii) and (iv)

( c ) (i) and (iv)                  (d) (iii) and ( ii)

( 2 ) Which one of the following organisms lack muscles and skeleton for movement?

( a ) Dog                             (b) Snail

( c ) Earthworm                 (d) Human being

(3) Upper jaw and skull joints are immovable .

( a) Shoulder and arm

(b) Knee and joint

( c ) Upper jaw and skull

(d) Lower jaw and jaw

(4) Why do underwater divers where fin- like flippers on their feet ?

( a) To swim easily in water .

( b) To look like a fish .

( c) To walk on water surface .

(d) To walk over the bottom of the sea

( sea bed).

( 5) External ear( pinna) is supported by

( a ) bone                    ( b ) cartilage

( c) tendon                 ( d) capsule

( 6 ) Cockroach moves with the help of it’s

( a ) leg      ( b) bone

( c ) muscular foot         ( d) whole body

(7) Which one of the following categories of vertebrae are correctly numbered ?

( a) Cervical -7                  ( b) Thoracic -10

(c) Lumbar – 4                  (d) Sacral –4

( II) Fill in the blanks .

1) Movement of organisms from place to place is called locomotion.

2 ) Movement refers to change in position of the part of an organism’s body.

3) Structure which provides rigid frame work to the body is called skeletonsystem.

4) Axil skeleton in human consists of skull, facial bones, ribs ,sternum and vertebral column.

5) Appendicular skeleton in human consists of pelvic and pectoral girdle.

6) The place where two bones meet is termed as joint.

7) Smooth muscle is attached to soft parts of the body like blood vessels, iris, bronchi and the skin.

8) Radial muscle makes pupil of eyes wider.

( III) State true or false, If false correct the statement.

1 ) Skull in humans consists of 22 bones.

This statement is true.

  • There are 12 pairs of ribs in human body.

This statement is true.

3 ) Pelvic girdle is a part of axial skeleton.

This statement is false.

Explanation:

Pelvic girdle is not a part of axial skeleton but rather ,it is a part of appendicular skeleton.

4 ) Hinge joint is slightly movable joint.

This statement is true.

5) Cardiac muscle is a voluntary muscle.

This statement is false.

Explanation:

Cardiac muscle is not a voluntary muscle but rather, it is an involuntary muscle.

6) The flexor and extensor muscle of the arm are antagonistic muscles.

This statement is true.

( IV) Answer very briefly.

1 ) What is skeleton ?

The skeleton system plays an important role in supporting and protecting the body by rendering the hard structure or framework to the human body. It mainly consists of bones, cartilage, tendons and ligaments. If there are no joints in the skeleton, then it would not facilitate any movements, which in turn will transform our body into a stone. Exoskeleton and Endoskeleton are mainly the two types of skeleton on the basis of presence in the body.

2 ) What is cranium?

Skull refers to a hard structure that is composed of small bones. A total of 22 bones are necessary in order to form the skull but a collective fixation of 8 bones leads to the formation of cranium.

3) Why our backbone is slightly movable?

Vertebrae are connected by grinding joints in such a manner, that it facilitates our body to bent back, front or side wards . Due to this reason, our backbone is slightly movable.

4) Differentiate axial and appendicular skeleton.

The differences between axial and appendicular skeleton are as follows :

Axial skeleton

The axial skeleton as the name suggests, refers to those bones that are located along the axis or at the centric point of the human body. The axial skeleton is composed of the skull ,facial bones , sterum, ribs and vertebral column.

Appendicular skeleton

The appendicular skeleton on the other hand, refers to those bones that are situated in the appendages of the body as well as those structures that performs an essential part in connecting the appendages to the axial skeleton. Appendicular skeleton mainly consists of the shoulder girdle, the arm, wrist and hand bones, the pelvic girdle, and the leg, ankle and foot bones.

5) What is ligament?

A joint is surrounded by bands of tough and elastic connective tissues that performs an essential role in rendering support and limiting the joint’s movement and this connective tissue is known by the term of ligaments.

 

6 ) Define muscle.

The means of all movements are provided by the muscles in the body. They help in covering the skeleton framework and also renders shape to the body. Muscles plays an important role in maintaining our body posture. Muscles refers to the long bundles of contractile tissue. Each muscle consists of two ends- a fix end refers to the originating point of muscle and a movable end on the other hand tends to drag some other parts.

 

7 ) Differentiate tendons and ligament.

The differences between tendons and ligaments are as follows :

Tendons

  • Tendons refers to the tough band of fibrous connective tissue that performs an essential role in connecting muscle tothe bone and portrays an ability to withstand tension.

 

Ligaments

  • A joint is surrounded by bands of tough and elastic connective tissues that performs an essential role in rendering support and limiting the joint’s movement and this connective tissue is known by the term of ligaments.

 

( V) Answer briefly.

1 ) Differentiate between the following.

a ) Movement and Locomotion

Movement

  • When one or more parts of the body changes the place or position, then it is known as movement.

 

  • They depict both voluntary or involuntary nature.

 

  • There is an occurrence of movement at the biological level.

 

  • Energy is always essential for promoting movement.

 

Locomotion

  • When an organism moves from one place to another place ,then it is known as locomotion.

 

  • They depict a voluntary nature.

 

  • There is an occurrence of locomotion at the organism level.

 

  • Energy is not always essential in case of locomotion.

 

  1. b) Endoskeleton and Exoskeleton

Endoskeleton

  • Endoskeleton refers to those skeleton that are present within the human body. The mesoderm represents the middle layer from which it originates. They contributes in forming the main body structure and are located in almost all vertebrates.

 

Exoskeleton

  • Exoskeleton is the skeleton that is present on the outermost layer of the body. Ectoderm or mesoderm represents the germ layer from which it originates. It’s primary function is to safeguard and preserve the inner organs ,just like the scales in the fishes and external hard layer of the tortoise.

 

c) Pectoral and pelvic girdle

Pectoral girdle

  • Pectoral girdle are mainly located in the shoulder area.

 

  • It contributes in providing articulation to forelimbs .

 

  • There is a separation in the shoulder blade and collar bone ,which means they remain apart from each other.

 

  • They are comparatively less heavy.

 

Pelvic girdle

  • It is located in the hip area.

 

  • It facilitates in rendering articulation to legs or hind limbs.

 

  • A single hip bone is formed by the fusion of three bones.

 

  • Due to their strong nature, they are capable of taking enough stress.

 

d) Ball and socket joint and hinge joint.

Ball and socket joint

  • There is an articulation of a ball shaped head of one bone with a cup like socket of an adjacent bone .

 

  • There is an occurrence of movement in three planes . This joint permits the largest variation of movement. Shoulder and hip depicts a perfect example.

 

Hinge joint

  • There is an articulation of a cylindrical protrusion of one bone with a tough- shaped  depression of an adjacent bone.

 

  • It restricts the movement to one plane. This joint facilitates only two movements , i.e. bending and straightening. Elbow and knee are some of the most relevant examples.

 

  1. e) Voluntary and Involuntary muscle

Voluntary muscle

  • Voluntary muscle are those muscles that are attached to the bones . Thesemusclesare mainly located in the arms, legs and neck. With the aid of will or conscious control , the movement of these muscles can be controlled. For this reason, this muscle is known as voluntary muscle.

 

Involuntary muscle

  • Involuntary muscle are those muscles that are attached to the delicate portions of the body such as blood vessels ,iris, bronchi and the skin. With the help of will, the movement of thesemuscle cannot be controlled, which means these muscle operates in an automatic manner. For this reason, this muscle is known as involuntary muscle.

 

2 ) What are antagonistic muscles?  Give one example.

Muscles always functions in pairs , which operates in opposition to one another. These are known as antagonistic pairs. Antagonistic muscles are situated in almost all over the body . There are two sets of muscles in the iris of the eye. The primary role of radical muscle is to widen the pupil  of the eye whereas,  circular muscles tends to shorten the pupil .

 

3) How is the skeleton of a bird well- suited for flying?

A bird possess streamlined body and it’s bones are quite strong and lighter. As they are void , so it contains air spaces between them. There is a modification of the lower part of limbs as claws, which enables them to promote walking or perching. In order to hold massive flight muscles, the breast bones are modified to such an extent that contributes in moving the wings upwards and downwards. Birds are provided with special flight muscles and there are modification of the  forelimbs as wings. The birds are capable of flying because they have elongated feathers in their wings and tail. Gliding and flapping are mainly the two types of flight that are depicted by birds.

 

4) What are the functions of skeleton in human body?

There are total five important functions, that are served by skeleton system in the human body. They are as follows :

  • It contributes in providing shape and structure to the body.

 

  • It maintains and covers the internal parts of the body.

 

  • The bones supplies two important minerals such as calcium and phosphorus, which is essential for the body to execute the regulatory functions.

 

  • There is a production of red blood cells in the bone marrow .

 

  • In order to operate muscular activities, the bones of the skeletal system functions like a lever. Tendons and ligaments plays an important role in promoting the muscular movement.

 

( VI) Answer in detail.

1 ) Name the different types of joints?Give one example for each type.

1 ) Ball and socket joint

  • There is an articulation of a ball shaped head of one bone with a cup like socket of an adjacent bone .

 

  • There is an occurrence of movement in three planes . This joint permits the largest variation of movement. Shoulder and hip depicts a perfect example.

 

2)  Hinge joint

  • There is an articulation of a cylindrical protrusion of one bone with a  tough- shaped  depression of an adjacent bone.

 

  • It restricts the movement to one plane. This joint facilitates only two movements , i.e. bending and straightening. Elbow and knee are some of the most relevant examples.

 

3) Pivot joint

  • There is an articulation of a rounded or pointed structure of one bone with a ring shaped structure of Radius Ulna- an adjacent bone.

 

  • This joint limits the movement to one plane, which means it facilitates rotation around its longitudinal axis only. Spine is one such example.

 

4) Condyloid joint

  • This joint portrays similarity with a ball and socket joint but the flatter articulatorysurfaces leads to the formation of shallower joint.

 

  • There is an occurrence of movement in two planes. This joint permits the second largest variation of movement. Wrist is one of the most relevant example.

 

5 ) Gliding joint

  • There is a flatter articulatory surfaces, that depicts a similar size.

 

  • Though gliding permits movement in three planes but it is restricted to a great extent. Spine is one of the perfect example.

 

  • Saddle joint
  • At one end, one part is concave and bears the resemblance of a saddle . Another part is convex, which is at the other end and bears the appearance of a rider in a saddle.

 

  • Movements such as flexion – extension and abduction- adduction are mostly seen. Thumb and shoulders are some of the most accurate examples.

 

2 ) Write about the human axial skeleton, giving suitable labelled diagram.

 

Axial skeleton

The axial skeleton as the name suggests, refers to those bones that are located along the axis or at the centric point of the human body. The axial skeleton is composed of the skull ,facial bones, sterum, ribs and vertebral column.

a ) Skull

Skull refers to a hard structure that is composed of small bones. A total of 22 bones are necessary in order to form the skull but a collective fixation of 8 bones leads to the formation of cranium and the face is formed by the fusion of 14 bones. The lower jaw is the joint which possess movable joint. Muscles and ligaments renders support to this movable joint.

 

b) Vertebral column

As it runs at the back of the body, for this reason it is known as spine or the backbone.  In order to provide support to the upper portion of the body, it is situated in the trunk region. Vertebral column is composed of individual bones, which is known by the term of vertebrae. The vertebral column is composed of total 33 vertebrae , i.e. 7 cervical vertebrae, 12 thoracic vertebrae, 5 lumbar vertebrae, 5 fused sacral vertebrae and 4 fused coccygeal vertebrae. Vertebral column takes the shape of a tube because it travels from the base of the skull to the hip bone.  There is a spinal cord that travels through this hollow tube. Vertebrae are connected by grinding joints in such a manner, that it facilitates our body to bent back, front or side wards .

The functions of vertebral column are as follows:

  • It renders protection to the spinal cord.
  • It provides support to the head.
  • It performs an important role by serving as an attachment for the ribs.
  • Without it’s help, it would not be possible to walk and stand erect with right posture.

c) Sternum or Rib cage

Rib cage is mainly situated in the chest area. It is composed of twelve pairs of ribs and depicts a cone shape structure. The curving of the ribs that are attached to the vertebrae at the back leads to the formation of a cage. At the front, there is an attachment of ten pairs of ribs to the breast bone. Free- floating ribs refers to  two pairs of lower ribs that are free at front. Rib cage undergoes both contraction and expansion during the process of breathing. Rib cage performs an important role in protecting the lungs, heart and some portion of liver.

3 ) Discuss various types of movement seen in living organisms.

Living organisms depicts three types of movement. They are :

Amoeboid movement

It is pseudopodia , which enables the occurrence of this movement. The movement of protoplasm inside a cell contributes in promoting the movement of an appendages.

Ciliary movement

It is cilia which contributes in bringing about this movement. Cilia represents the hair – like extensions of the epithelium. The cells of the lymphatic system plays an important role in portraying these two kinds of movements.

Muscular movement

It is musculoskeletal system , which performs a significant role in bringing about this movement and this movement is quite complex in nature. The higher vertebrates depicts this kind of movement.

4 ) What is a streamlined body? How does it help in the movement of animals that fly or swim in water? 

Fish possess streamlined body because it helps them to proceed swiftly with the flowing water. Muscles, fins and the tail plays an essential role in maintaining the balance. Fish have streamlined body, for the purpose of lowering the friction while swimming in water. They are also provided with strong muscles, which contributes in swimming. When a fish starts swimming, its front part tends to curve at one direction and the tail part remains on the other side. When it takes the next turn, then the front part tends to curve at the opponent side and the tail part alters it’s position to the other side . So, the tail fin functions in such a manner that contributes in changing the direction.

5 ) Write a short note on different types of muscles.

Voluntary muscle

  • Voluntary muscles are those muscles that are attached to the bones . These muscles are mainly located in the arms, legs and neck. With the aid of will or conscious control , the movement of these muscles can be controlled. For this reason, this muscle is known as voluntary muscle.

Involuntary muscle

  • Involuntary muscle are those muscles that are attached to the delicate portions of the body such as blood vessels ,iris, bronchi and the skin. With the help of will, the movement of thesemuscles cannot be controlled, which means these muscle operates in an automatic manner. For this reason, this muscle is known as involuntary muscle.

Cardiac muscle

  • Cardiac muscle is situated only in the heart .
  • It’s main function is to pump blood in every part of your body by adopting involuntary movements. This in turn helps to regulate the contractions of our heart.
Updated: December 6, 2021 — 12:32 pm

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  1. nice to read the notes

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