ICSE Class 9 Biology Solutions Chapter 12 Skeleton – Movement and Locomotion

Class 9th ICSE Biology Solutions Chapter 12 Skeleton – Movement and Locomotion

Progress Check

Fill in the blanks :
(i) Our skeleton consists of bones,……………….. and ………………..
(ii) is the chief component of our skeleton.
(iii) Shape wise the bones can be classified as ……….. and
(iv) The central hollow part of the long bones it known as ………………..
(v) A bone becomes soft and flexible when placed in dilute ………………..
Answer:
(i) cartilage, ligaments
(ii) bone
(iii) long, short, flat, irregular
(iv) bone marrow
(v) hydrochloric acid.

Progress Check

Mention if the following statements are true (T) or false (F):
(i) Humerus of the upper arm is the longest bone. T/F
(ii) Axial skeleton includes shoulder and hip girdles. T/F
(iii) There are 10 vertebrae in the neck. T/F
(iv) There are three kinds of ribs – true, false and floating. T/F
(v) The shoulder girdle is large and trough-shaped.
Answer:
(i) False (Femur)
(ii) False (Appendicular)
(iii) False (7 vertebrae)
(iv) True
(v) False (Hip girdle)

Progress Check

Question 1.
Mention if the following statements are true (T) or false
(i) The flexor and extensor muscles of the arm T/F are antagonistic muscles.
(ii) Muscles can contract as well as elongate T/F
(iii) Muscles are attached to bones by ligaments T/F
(iv) Cardiac muscle is a voluntary muscle T/F
(v) Bending of arm on elbow is an example of T/F first order of lever mechanism
Answer:
(i) True
(ii) False (relax)
(iii) False (Tendons)
(iv) False
(v) True.

Question 2.
Match the bones (Column I) with the kind of joint (Column II)
Column I (Bones)
(i) Humerus and shoulder girdle
(ii) TWO adjacent vertebrae
(iii) Skull and upper end of back-bone
(iv) Bones of brain box
(v) Rib and breast bone
Answer:
(i) – (d),
(ii) – (b),
(iii) – (e),
(iv) – (c),
(v) – (a)

Review Questions

A. Multiple Choice type :

Question 1.
Your external ear (pinna) is supported by
(a) Bone
(b) Cartilage
(c) Tendon
(d) Capsule
Answer:
(b) Cartilage

Question 2.
The type of joint found at shoulder is also found at
(a) Elbow
(b) Knee
(c) Ankle
(d) Hip
Answer:
(d) Hip

Question 3.
Which one the following categories of vertebrae are correctly numbered
(a) Cervical – 7
(b) Thoracic – 10
(c) Lumbar -4
(d) Sacral – 4
Answer:
(a) Cervical – 7

Question 4.
Human skeleton altogether contains 213 bones. Which of these are the 6 bones?
(a) Neck vertebrae
(b) Ear ossicles
(c) Carpals
(d) Metacarpals
Answer:
(b) Ear ossicles

B. Very Short Answer Type

Question 1.
Name the parts of the skeleton where the following are located: transverse process, glenoid cavity, shoulder- blade, acetabulum.
Answer:
Transverse process – Neural arches in Vertebrae
Glenoid cavity – Pectoral girdle ,
Shoulder blade – Shoulder girdle
Acetabulum – Pelvic girdle

Question 2.
Name any two parts of your body where the supporting skeleton is made of cartilage instead of bone.
Answer:

1. External ear,
2. nose.

C. Short Answer Type

Question 1.
What is the difference between a true rib and a floating rib?
Answer:
True ribs. The first seven pairs of ribs, attached directly to the sternum by means of coastal cartilages are called as true ribs.
Floating ribs. The last two pairs of ribs, not connected to the sternum at all are known as floating ribs.

Question 2.
Do the muscles pull the structures, or push them? Explain briefly.
Answer:
Each muscle usually has two ends, a fixed end where the muscle originates and a movable end which pulls some other part. This movable end is drawn out to form a tough structure ‘ called tendon. Tendon is attached to the bone. The muscles when stimulated by a nerve, contracts, become shorter and thicker and thus it pulls the bone at the movable end.

Question 3.
Just as the humerus corresponds to femur, what bones correspond to tarsals, metacarpals, ulna and radius respectively?
Answer:

bones	Corresponding bones
trasals	carpals
metatarsals	metatarsals
ulna	fibula
radius	tibia

Question 4.
What are antagonistic muscles? Give one example.
Answer:
Skeletal Muscles work in pairs, each opposing the action of the other in the pair, like some muscles contracting while others relaxing., Muscles which produce opposite movements are called antagonistic muscles.

The biceps and triceps of hand are antagonists. When biceps contract the arm is pulled upward (bending of lower arm over the upper arm) in this position the triceps relax. When the triceps contract, the biceps, relax so the lower arm is straightened. Therefore these two muscles are antagonistic.

Question 5.
Some people in old age complain of stiff joints. What do you think could be a possible reason for it?
Answer:
Some joints like shoulder joint, knee joint need to be held firmly in position to be well lubricated. Such joints contain lubricating fluid called the synovial fluid, which serves as a cushion between the bones and removes friction during movements. In the old age, the amount of synovial fluid gets reduced and due to loss of lubrication and increased friction people complain of stiff joints.

D. Long Answer Type

Question 1.
What are the uses of skeleton in our body?
Answer:
The endoskeleton of vertebrates is made of bones and cartilages and has following important uses :

• It affords protection to delicate organs of the body such as heart, lungs, brain, spinal cord, sense organ etc.
• It provide support to the body and helps in preserving a definite shape.
• It provides a suitable surface for the attachment of the muscles and ligaments.
• Some bones provide lever arrangement.
• Some part of the skeleton help in breathing and hearing.

Question 2.
What are the different types of joints? Give one example of each type.
Answer:
A joint is formed where two or more bones meet. These are of following types :
1. Immovable joints. In this no movement is possible between
the two bones. The sutures between the bones of the brain box are examples of immovable joint.

2. Partially movable joints. Slight movement is possible between two bones. The joints between rib and the breast bone or between the vertebrae are the examples \of above joints.

3. Movable joints. Varying degrees of movement are possible between the two jointed bones. Movable joints are of four types :

• Hinge joints allow the movement in one plane only e.g. between the humerus and ulna and in the knees, elbows, fingers etc.
• Ball and socket joints allow the greatest freedom of movement e.g., shoulder joint and hip joint.
• Gliding joints between the bones of the wrist and those of the ankles.
• Pivot joints allow rotation about an axis e.g. the juncture between the head and the upper end of the back bone.

4. Synovial joints. Some joints allow considerable degree of movement e.g. the knee joint is held in position by strong ligaments and well protected by an outer fibrous layer.

Question 3.
What is the difference between ligament and tendon ? What are their functions ?
Answer:

Tendon	Ligament
1. Tendons connect muscles to bones 2. Tendons are inelastic. 3. They are arranged in bundles. 4. They are made of white fibres or collagen fibres.	Ligaments connect two bones. Ligaments are elastic. They are arranged freely. They are formed of yellow fibres or elastic fibres.

Function of Tendons.

• Attach muscles to the portions of the skeleton.
• Serves to move the various bones and cartilages of the skeleton.

Function of Ligament

1. Serves to strengthen the joints.
2. Prevents dislocation.
3. Sometimes covers the exposed portion of the joint.

Question 4.
What are bones made of? Are the bones living or non-living? Give reason.
Answer:
Bone is the main component of our skeletal system. It is made up of organic and inorganic materials. Nearly two third part of the entire bone substance is inorganic i.e. made up of calcium, phosphate and carbonate. The rest is organic material consisting largely of fibrous protein collagen. Bone is a highly calcified, hard and rigid, though, living skeletal tissue. It consists of bone cells in the form of concentric rings called oesteocytes containing collagen fibres and mineral salts.

The external surface of the bone is covered by membrane called periosteum which is richly supplied with blood vessels. A long bone has a hollow cavity in the middle, filled with bone marrow which give rise to ei,ther white blood cells or red blood cells. Thus, the! bone &s long as present in the living body is living but when taken out its cells dies and the bone is said to be dead (non-living).

Question 5.
Given below is a diagram of human skeleton. Name the bones numbered 1-11.

Answer:

1. Skull
2. Clavicle
3. Sternum
4. Humerus
5. Ulna
6. Pelvis
7. Ribs
8. Radius
9. Femur
10. Tibia
11. Fibula

Additional Questions

Question 1.
(a) What is a joint?
(b) Match the description in column A with the appropriate picture in column B.
A
(i) Pivot Joint: One bone acts as the pivot and another rotates over it.

(ii) Ball-and-Socket Joint: Allows maximum movement in all direc-tions.

(iii) Gliding Joint: Only side to side c and back and forth movement permitted.

(iV) Hinge Joint: Allows backward and forward movement in one plane only.
d.

Answer:
(a) A joint is a point of contact between the bones and cartilage or between the teeth and bones.
(b) (i)
(c) (ii)
(a) (iii)
(d) (iv)

Question 2.
What is a synovial joint?
Answer:
A joint in which there is a space between articulating bones is called synovial joint The joint enables free movement eg. elbow joint.

Question 3.
Give one example of each
(i) Immovable joint.
(ii) Partially movable joint
Answer:
(i) Bones of the skull
(ii) Between the bodies of the vertebrae in the vertebral column.

Question 4.
Identify the four types of movable joints visible in lower part of the human body from the pelvic girdle to the feet – (in figure (i)
Answer:

1. Ball and socket joint in hip
2. Hinge joint at knee
3. Gliding joint at ankle
4. Gliding joint at toe.

Question 5.
(a) In producing body movement, bones act as levers and joints act as fulcrums of these levers. In figure (ii), mark the fulcrum (F), load (R) that has to be overcome and the point where effort (E) has to be applied.
(b) To bring about movement, two muscles work in opposition. Label the two types of muscles in figure (ii) and state the function of each.
Answer:
The two types of muscles are

1. Extensor muscle
2. Flexor muscle

1. Extensor muscle:

They straighten a joint

2. Flexor muscle:
They bend a joint

ICSE Class 9 Biology Solutions