Question 1: Which are different types of muscular tissues?

Step-by-step solution provided.

Question 6: State the functions of:

Can you recall?(Textbook Page No. 193) Question 1. Name the part of human skeleton situated along the vertical axis. Answer: Axial skeleton

Question 4: Question 1. Why do muscles show spasm after rigorous contraction?

Step-by-step solution provided.

Question 2: Why do we shiver during winter?

Step-by-step solution provided.

Question 1: Why are movement and locomotion necessary among animals?

Step-by-step solution provided.

Question 4: What are antagonistic muscles? Explain with example.

Step-by-step solution provided.

Question 6: Differentiate between: i. Flexor and extensor muscles

Step-by-step solution provided.

Question 2: Why are muscle rich in creatine phosphate?

Step-by-step solution provided.

Maharashtra State Board Class 11 (FYJC / HSC) Biology Solutions Chapter 16 Skeleton and Movement - Digest Answers | Maharashtra Board Solutions

Solution & Step-by-Step Answer:

Question (B).
Observe the diagram and enlist importance of ‘A’, ‘B’ and ‘C’.

Answer:

Question (C).
Raju intends to train biceps; while exercising using dumbbells, which joints should remain stationary and which should move?
Answer:
While performing exercise of biceps using dumbbells, the joint which should remain stationary are wrist joint or radiocarpal joint, ball and socket joint of shoulder. The only joint which should move is hinge joint of elbow.

Question (D).
In a road accident, Moses fractured his leg. One of the passers by, tied a wodden plank to the fractured leg while Moses
was rushed to the hospital Was this essential? Why?
Answer:

Question (E).
Sprain is more painful than fracture. Why?
Answer:

[Note: 1^stand 2^nddegree sprains are not very serious and may be lesser painful than a fracture. Depending on the severity of the injury, intensity of pain will vary.]

Question (F).
Why a red muscle can work for a prolonged period whereas white muscle fibre suffers from fatigue after a shorter work? (Refer to chapter animal tissues.)
Answer:

Thus, red muscle fibres can perform prolonged work and show less fatigue due to accumulation of negligible amount loss or of lactic acid, whereas white muscle fibres suffer from fatigue after a shorter work due to accumulation of higher amount of lactic acid.

3. Answer the following questions in detail

Question (A).
How is the structure of sarcomere suitable for the contractility of the muscle? Explain its function according to sliding
filament theory. (Refer to chapter animal tissues.)
Answer:
i. Sarcomere is the functional unit of myofibril. It has specific arrangement of actin and myosin filaments. The components of sarcomere are organized into variety of bands and zones. Actin and myosin are referred as contractile proteins. Actin is called as thin filament whereas myosin in called as thick filament. The structure of sarcomere:

ii. ‘A’ band – dark bands present at the centre of sarcomere and contain myosin as well as actin.
‘H’ zone or Hensen’s zone – light area present at the centre of ‘A’ band
‘M’ line – present at the centre of ‘H’ zone
‘I’ band – light bands present on the either side of ‘A’ band containing only actin
Z’ line – adjacent ‘I’ bands are separated by ‘Z’ line.

iii. Sliding filament theory: It was put forth by H.E Huxley and A.F Huxley. It is also known as ‘Walk along theory’ or Ratchet theory.

Question (B).
Ragini, a 50 year old office goer, suffered hair-line cracks in her right and left foot in short intervals of time. She was worried about minor jerks leading to hair line cracks in bones. Doctor explained to her why it must be happening and prescribed medicines.

What must be the cause of Ragini’s problem? Why has it occurred? What precautions she should have taken earlier? What care she should take in future?
Answer:

Question (C).
How does structure of actin and myosin help muscle contraction?
Answer:
i. Myosin filament:

ii. Actin filament: It is a complex type of contractile protein. It is made up of three components:

Question (D).
Justify the structure of atlas and axis vertebrae with respect to their position and function.
Answer:
i. Atlas vertebrae:

ii. Axis vertebrae:

Question (E).
Observe the blood report given below and diagnose the possible disorder.

Answer:
On observing Report D, it is clear that the level of uric acid is more than normal, thus the patient must be suffering from gouty arthritis.

Also, the elevated blood urea nitrogen (BUN) indicates dysfunctional liver and/ or kidneys. It generally occurs due to decrease in GFR, caused by renal disease or obstruction of urinary tract.

Question 4 Maharashtra Board Solution

Write short notes on following points

Question (A).
Actin filament

Solution & Step-by-Step Answer:

Actin filament: It is a complex type of contractile protein. It is made up of three components:

Question (B).
Myosin filament
Answer:
i. Myosin filament:

Question (C).
Role of calcium ions in contraction and relaxation of muscles.
Answer:
Calcium ions play a major role in contraction and relaxation of muscles.

Question 5 Maharashtra Board Solution

Draw labelled diagrams

Question (A).
Synovial joint.

Solution & Step-by-Step Answer:

i. Synovial joints / freely movable joints / diarthroses:

1. Pivot joint: In this type of joint, the rounded or pointed surface of one bone articulates with a ring formed partly by another bone and partly by the ligament. Rotation only around its own longitudinal axis is possible. e.g. in joint between atlas and axis vertebrae, head turns side ways to form ‘NO’ joint.

2. Ball and socket joint: The ball like surface of one bone fits into cup like depression of another bone forming a movable joint. Multi-axial movements are possible. This type of joint allows movements along all three axes and in all directions. e.g. Shoulder and hip joint.

3. Hinge joint: In a hinge joint, convex surface of one bone fits into concave surface of another bone. In most hinge joints one bone remains stationary and other moves. The angular opening and closing motion (like hinge) is possible. In this joint only mono-axial movement takes place like flexion and extension. e.g. Elbow and knee joint.

4. Condyloid joint: It is an ellipsoid joint. The convex oval shaped projection of one bone fits into oval shaped depression in another bone. it is a biaxial joint because it permits movement along two axes viz, flexion, extension, abduction, adduction and circumduction is possible. e.g. Metacarpophalangeal joint.

5. Gliding joint: It is a planar joint, where the articulating surfaces of bones are flat or slightly curved. These joints are non-axial because the motion they allow does not occur along an axis or a plane. e.g. Intercarpal and intertarsal joints.

6. Saddle joint: This joint is a characteristic of Homo sapiens. Here the articular surface of one bone is saddle-shaped and that of other bone fits into saddle (each bone forming this joint have both concave and convex areas). It is a modified condyloid joint in which movement is somewhat more free. It is a biaxial joint that allows flexion, extension, abduction, adduction and circumduction.
e.g. Carpometacarpellar joint between carpal (trapezium) and metacarpal of thumb.

Question (B).
Different cartilagenous joints.
Answer:
Cartilaginous / slightly movable joints / amphiarthroses:
These joints are neither fixed nor freely movable. Articulating bones are held together by hyaline or fibrocartilages. They are further classified as

a. Synchondroses: The two bones are held together by hyaline cartilage. They are meant for growth. On completion of growth, the joint gets ossified, e.g. Epiphyseal plate found between epiphysis and diaphysis of a long bone, Rib – Sternum junction.

b. Symphysis: In this type of joint, broad flat disc of fibrocartilage connects two bones. It occurs in mid-line of the body. e.g. Intervertebral discs, manubrium and sternum, pubic symphysis.

Practical / Project :

Identify the following diagrams and demonstrate the concepts in classroom.

Answer:
The diagrams A, B and C represent Class I, Class II and Class III lever respectively.
For description:

[Students are expected to perform the given activity on their own]

12th Biology Digest Chapter 16 Skeleton and Movement Intext Questions and Answers

Movements And Locomotion (Textbook Page No. 193)

Question 1 Maharashtra Board Solution

Streaming of protoplasm, peristalsis, walking, running, etc. Which of the above-mentioned movements are internal? Which are external? Can you add few more examples?

Solution & Step-by-Step Answer:

Can you recall?(Textbook Page No. 193)

Question 1 Maharashtra Board Solution

Which are different types of muscular tissues?

Solution & Step-by-Step Answer:

Question 2 Maharashtra Board Solution

Name the type of muscles which bring about running and speaking.

Solution & Step-by-Step Answer:

Skeletal muscles (Voluntary muscles)

Question 3 Maharashtra Board Solution

Name the muscles which do not contract as per our will.

Solution & Step-by-Step Answer:

Involuntary muscles (smooth muscles and cardiac muscles)

Question 4 Maharashtra Board Solution

Which type of muscles show rhythmic contractions?

Solution & Step-by-Step Answer:

Cardiac muscles

Question 5 Maharashtra Board Solution

Which type of muscle is present in the diaphragm of the respiratory system?

Solution & Step-by-Step Answer:

Skeletal muscle

Question 6 Maharashtra Board Solution

State the functions of:

Solution & Step-by-Step Answer:

Can you recall?(Textbook Page No. 193)

Question 1 Maharashtra Board Solution

Name the part of human skeleton situated along the vertical axis.

Solution & Step-by-Step Answer:

Axial skeleton

Question 2 Maharashtra Board Solution

Give an account of bones of human skull.

Solution & Step-by-Step Answer:

Skull is made up of 22 bones. It is located at the superior end of vertebral column. The bones of skull are joined by fixed or immovable joints except for jaw.

Skull consists of cranium or brain box and facial bones.

i. Cranium: It is made up of four median bones and two paired bones.

ii. Facial Bones: Fourteen facial bones give a characteristic shape to the face. The growth of face stops of the
age of 16.
Following bones comprise the facial bones:

Think about it.(Textbook Page No. 193)

Question 1 Maharashtra Board Solution

Did you ever feel tickling in muscles?

Solution & Step-by-Step Answer:

Yes, the tickling sensation in muscles can be felt and sometimes it is also accompanied by itching sensation.

Question 2 Maharashtra Board Solution

What is locomotion?

Solution & Step-by-Step Answer:

The change in locus of whole body of living organism from one place to another place is called locomotion.

Question 3 Maharashtra Board Solution

State the four basic types of locomotory movements seen in animals.

Solution & Step-by-Step Answer:

The four basic types locomotory movements seen in animals are:

Question 4 Maharashtra Board Solution

Question 1 Maharashtra Board Solution

Why do muscles show spasm after rigorous contraction?

Solution & Step-by-Step Answer:

block bg-white dark:bg-slate-900/80 border-l-4 border-emerald-500 rounded-r-xl p-5 my-3 shadow-xs border border-slate-200/60 dark:border-slate-800">

Solution & Step-by-Step Answer:

Question 2 Maharashtra Board Solution

Why do we shiver during winter?

Solution & Step-by-Step Answer:

Can you tell?(Textbook Page No. 194)

Question 1 Maharashtra Board Solution

Why are movement and locomotion necessary among animals?

Solution & Step-by-Step Answer:

Question 2 Maharashtra Board Solution

All locomotions are movements but all movements are not locomotion. Justify

Solution & Step-by-Step Answer:

Locomotion occurs when body changes its position, however all movements may not result in locomotion. Thus, all locomotions are movements but all movements are not locomotion.

Question 3 Maharashtra Board Solution

Kriti was diagnosed with knee tendon injury. She asked the doctor whether she will be able to walk due to the injury? If not then state the reason.

Solution & Step-by-Step Answer:

Knee tendon injury affects the ability to walk. Kriti may not be able to walk freely as the tendons attached to the bones help in the movement of the parts of skeleton.

Question 4 Maharashtra Board Solution

What are antagonistic muscles? Explain with example.

Solution & Step-by-Step Answer:

Question 5 Maharashtra Board Solution

Describe the antagonistic muscles in detail.

Solution & Step-by-Step Answer:

Following are the important antagonistic muscles:

Question 6 Maharashtra Board Solution

Differentiate between: i. Flexor and extensor muscles

Solution & Step-by-Step Answer:

	Flexor Muscles		Extensor Muscles
a.	Flexor muscles contract and bring about the bending or flexion of joint.	a.	Extensor muscles contract and bring about the straightening or extension of joint.
b.	These muscles decrease the angle between the bones on two sides of a joint.	b.	These muscles increase the angle between the components of limb.
e.g.	Biceps	e.g.	Triceps

ii. Pronator and supinator: Pronator turns the palm downwards and supinator turns the palm upward.

Can you recall? (Textbook Page No. 194)

Question 1 Maharashtra Board Solution

Comment on contraction of skeletal muscles.

Solution & Step-by-Step Answer:

Skeletal muscles show quick and strong voluntary contractions. They bring about voluntary movements of the body. For mechanism of muscle contraction:

When the muscles are relaxed, the active sites remain covered with tropomyosin and troponin complex. Due to this, myosin cannot interact with active site of actin and thus contraction cannot occur.

Do You Know How (Textbook Page No. 195)

Question 1 Maharashtra Board Solution

Do skeletal muscles contract and bring about movement and locomotion?

Solution & Step-by-Step Answer:

When the muscles are relaxed, the active sites remain covered with tropomyosin and troponin complex. Due to this, myosin cannot interact with active site of actin and thus contraction cannot occur.

Internet my friend. (Textbook Page No. 196)

Question 1 Maharashtra Board Solution

Collect information about‘T’ tubules of sarcoplasmic reticulum.

Solution & Step-by-Step Answer:

Can you tell?(Textbook Page No. 197)

Question 1 Maharashtra Board Solution

Explain the chemical changes taking place in muscle contraction.

Solution & Step-by-Step Answer:

The muscle undergoes various chemical changes during contraction, they are as follows:

Question 2 Maharashtra Board Solution

Why are muscle rich in creatine phosphate?

Solution & Step-by-Step Answer:

Question 3 Maharashtra Board Solution

Explain the mechanism of muscle contraction and relaxation.

Solution & Step-by-Step Answer:

Mechanism of muscle contraction:

When the muscles are relaxed, the active sites remain covered with tropomyosin and troponin complex. Due to this, myosin cannot interact with active site of actin and thus contraction cannot occur.

Muscle relaxation: During relaxation, all the events occur in reverse direction as that of muscle contraction.

Question 4 Maharashtra Board Solution

What do you understand by muscle twitch?

Solution & Step-by-Step Answer:

Single muscle twitch:

Single muscle twitch: It is a muscle contraction initiated by a single brief-stimulation. It occurs in 3 stages: a latent period of no contraction, a contraction period and a relaxation period.

Do You Know How(Textbook Page No. 198)

Question 1 Maharashtra Board Solution

Exoskeletal components change from lower to higher group of animals. These include chitinous structures, nails, horns, hooves, scales, hair, shell, plates, fur, muscular foot, tube feet, etc.

Question 1 Maharashtra Board Solution

Do you know any of these exoskeletal structures help in movement and locomotion?

Solution & Step-by-Step Answer:

block bg-white dark:bg-slate-900/80 border-l-4 border-emerald-500 rounded-r-xl p-5 my-3 shadow-xs border border-slate-200/60 dark:border-slate-800">

Solution & Step-by-Step Answer:

Nails, hooves, scales, plates, muscular foot and tube feet help in movement and locomotion.

Question 2 Maharashtra Board Solution

How do scales and plates help in movement and locomotion?

Solution & Step-by-Step Answer:

Scales and plates in reptiles like snakes provide grip to move on rough edgy surfaces.

Question 3 Maharashtra Board Solution

Are scales of a fish and that of snake similar?

Solution & Step-by-Step Answer:

Fishes have dermal scales (bony scales), whereas reptiles like snakes have epidermal scales or scutes (horny, tough extensions of outer layer of skin i.e., stratum corneum).

Question 4 Maharashtra Board Solution

Find out more information about exoskeletal structures and their role in movement and locomotion.

Solution & Step-by-Step Answer:

Exoskeletal structures: Exoskeleton provide support, help in movement and also provides protection from predators. The exoskeletal structures vary from organism to organism. Echinoderms have tube feet for locomotion whereas molluscs (e.g. Chiton) have muscular foot for movement and locomotion

[Students are expected to find out more information about exoskeletal structures on their own.]

Question 2 Maharashtra Board Solution

Name the tissues that form the structural framework of the body.

Solution & Step-by-Step Answer:

Cartilage and bone

Do you remember?(Textbook Page No. 198)

Question 1 Maharashtra Board Solution

What are the components of skeletal system?

Solution & Step-by-Step Answer:

The components of skeletal system are bones, tendons, ligaments and joint.

Question 2 Maharashtra Board Solution

What type of bones are present in our body?

Solution & Step-by-Step Answer:

Long bones, short bones, flat bones, irregular bones and sesamoid bones.

Question 3 Maharashtra Board Solution

How do bones help in various ways?

Solution & Step-by-Step Answer:

Use your brain power.(Textbook Page No. 198)

Question 1 Maharashtra Board Solution

Can you compare bone, muscle and joint which help in locomotion with any simple machines you have studied earlier?

Solution & Step-by-Step Answer:

Bone, muscle and joint can be compared to the simple machines called levers. Joints act as fulcrum, respective muscle generates the force required to move the bone associated with joint.

Question 2 Maharashtra Board Solution

Explain the three types of lever found in human body.

Solution & Step-by-Step Answer:

The three types of lever are as follows:

Use your brain power.(Textbook Page No. 199)

Question 1 Maharashtra Board Solution

Why are long bones slightly bent and not straight?

Solution & Step-by-Step Answer:

Identify and label.(Textbook Page No. 199)

Question 1 Maharashtra Board Solution

Identify the different bones.

Solution & Step-by-Step Answer:

Identify and label.(Textbook Page No. 200)

Question 1 Maharashtra Board Solution

Name A, B, C and D from the given figure and discuss in group.

Solution & Step-by-Step Answer:

A – Coronal suture, B – Sagittal suture, C – Lambdoidal suture, D – Lateral / Squamous suture

Skull has many sutures (type of immovable joints) present, out of which four prominent ones are:

Can you tell?(Textbook Page No. 201)

Question 1 Maharashtra Board Solution

Give schematic plan of human skeleton.

Solution & Step-by-Step Answer:

[Note: Numbers in the bracket indicate the number of bones.]

Can you tell?(Textbook Page No. 201)

Question 1 Maharashtra Board Solution

Enlist the bones of cranium.

Solution & Step-by-Step Answer:

Cranium: It is made up of four median bones and two paired bones.

Can you tell?(Textbook Page No. 201)

Question 1 Maharashtra Board Solution

Write a note on structure and function of skull.

Solution & Step-by-Step Answer:

i. Structure of skull: Skull is made up of 22 bones. It is located at the superior end of vertebral column. The bones of skull are joined by fixed or immovable joints except for jaw.

Skull consists of cranium or brain box and facial bones.

i. Cranium: It is made up of four median bones and two paired bones.

ii. Facial Bones: Fourteen facial bones give a characteristic shape to the face. The growth of face stops of the age of 16.
Following bones comprise the facial bones:

ii. Functions of skull:

Internet my friend.(Textbook Page No. 201)

Question 1 Maharashtra Board Solution

Cleft palate and cleft lip

Solution & Step-by-Step Answer:

[Students are expected to find more information about Cleft Palate and lip on internet.]

Can you tell?(Textbook Page No. 202)

Question 1 Maharashtra Board Solution

Why skull is important for us? Enlist few reasons.

Solution & Step-by-Step Answer:

Functions of skull:

Internet my friend.(Textbook Page No. 202)

Question 1 Maharashtra Board Solution

Find out information about sinuses present in skull, functions of skull and disorder ‘sinusitis’.

Solution & Step-by-Step Answer:

Sinuses are the hollow cavities present in the skull. They humidify the air we breathe.

i. The four types of sinuses present in the skull:

ii. Functions of skull:

Functions of skull:

iii. Sinusitis: It is the inflammation of tissue lining the sinuses. Healthy sinuses when get blocked with mucus and germs causing infection which may lead to sinusitis.

[Students are expected to find more information about sinusitis, using the internet.]

Something interesting.(Textbook Page No. 202)

Question 1 Maharashtra Board Solution

If police suspect strangulation, they carefully inspect hyoid bone and cartilage of larynx. These get fractured during strangulation. V arious such investigations are done in case of suspicious death of an individual where ossification of sutures in skull, width of pelvic girdle, etc. are examined to find out approximate age of victim or gender of victim, etc. You may find out information about forensic science.

Solution & Step-by-Step Answer:

Forensic science is an application of science which is used in the matter of criminal determination and civil law. It is generally used in investigation of crimes. Forensic scientists collect, preserve and analyze the evidence during the course of investigation. [Students are expected to find more information about forensic science on internet.]

Try this.(Textbook Page No. 202)

Question 1 Maharashtra Board Solution

Feel your spine (vertebral column). Is it straight or curved?

Solution & Step-by-Step Answer:

Our spinc shows four slight curves which are visible when viewed from the sides.

Question 2 Maharashtra Board Solution

Find information about slipped disc. (Textbook page no.202)

Solution & Step-by-Step Answer:

If the ligaments of the intervertebral discs become injured, the pressure developed in the nucleus pulposus protrudes posteriorly or into one of the adjacent vertebrae. This is known as slipped disc.

[Students are expected to find more information using the internet.]

Can you tell?(Textbook Page No. 204)

Question 1 Maharashtra Board Solution

Write a note on curvatures of vertebral column and mention their importance.

Solution & Step-by-Step Answer:

Question 2 Maharashtra Board Solution

Explain the structure of typical vertebra.

Solution & Step-by-Step Answer:

Question 2 Maharashtra Board Solution

How will you identify a thoracic vertebra?

Solution & Step-by-Step Answer:

Thoracic vertebrae can be identified on the basis of centrum, as the centrum of the thoracic vertebrae is heart shaped.

Can you recall?(Textbook Page No. 206)

Question 1 Maharashtra Board Solution

How does humerus form ball and socket joint? Where is it located?

Solution & Step-by-Step Answer:

The head of humerus fits into the glenoid cavity of scapula and forms ball and socket joint. it is located in shoulder and hips.

Can you tell?(Textbook Page No. 208)

Question 1 Maharashtra Board Solution

Differentiate between the skeleton of palm and foot.

Solution & Step-by-Step Answer:

	Skeleton of palm	Skeleton of foot
a.	It consists of metacarpals and phalanges	It consists of metatarsals and phalanges
b.	Saddle joints and condyloid joints are in the palm.	Condyloid or saddle joints are not present the foot.

Question 2 Maharashtra Board Solution

Explain the longest bone in human body.

Solution & Step-by-Step Answer:

Femur: The thigh bone is the longest bone in the body. The head is joined to shaft at an angle by a short neck. It forms ball and socket joint with acetabulum cavity of coxal bone. The lower one third region of shaft is triangular flattened area called popliteal surface. Distal end has two condyles that articulate with tibia and fibula.

Internet my friend.(Textbook Page No. 212)

Question 1 Maharashtra Board Solution

Find out information about types of fractures and how they heal.

Solution & Step-by-Step Answer:

[Source: Tortora, G., Derrickson, B. Principles of Anatomy and Physiology. 15^thEdition]

[Students are expected to find out more information about healing of fractures using the internet.]

Do you remember?(Textbook Page No. 208)

Question 1 Maharashtra Board Solution

What are joints? What are the types?

Solution & Step-by-Step Answer:

i. A point where two or more bones get articulated is called joint or articulation or athrosis. They are classified based on degree of flexibility or movement they permit into lastly synovial or freely movable or diarthroses type of joints.

ii. Synarthroses / fibrous joints / movable joints:
In this joint, the articulating bones are held together by means of fibrous connective tissue. Bones do not exhibit movement. Hence, it is immovable or fixed type of joint. Synarthroses are further classified into sutures, syndesmoses and gomphoses.

iii. Cartilaginous / slightly movable joints / amphiarthroses:
These joints are neither fixed nor freely movable. Articulating bones are held together by hyaline or
fibrocartilages. They are further classified as

iv. Synovial joints / freely movable joints / diarthroses:

g. The types of synovial joints are on follows:

1. Pivot joint: In this type of joint, the rounded or pointed surface of one bone articulates with a ring formed partly by another bone and partly by the ligament. Rotation only around its own longitudinal axis is possible. e.g. in joint between atlas and axis vertebrae, head turns side ways to form ‘NO’ joint.

2. BaIl and socket joint: The ball like surface of one bone fits into cup like depression of another bone forming a movable joint. Multi-axial movements are possible. This type of joint allows movements along all three axes and in all directions. e.g. Shoulder and hip joint.

3. Hinge joint: In a hinge joint, convex surface of one bone fits into concave surface of another bone. In most hinge joints one bone remains stationary and other moves. The angular opening and closing motion (like hinge) is possible. In this joint only mono-axial movement takes place like flexion and extension. e.g. Elbow and knee joint.

4. Condyloid joint: It is an ellipsoid joint. The convex oval shaped projection of one bone fits into oval shaped depression in another bone. It is a biaxial joint because it permits movement along two axes viz, flexion, extension, abduction, adduction and circumduction is possible. e.g. Metacarpophalangeal joint.

5. Gliding joint: It is a planar joint, where the articulating surfaces of bones are flat or slightly curved. These joints are non-axial because the motion they allow does not occur along an axis or a plane. e.g. Intercarpal and intertarsal joints.

Saddle joint: This joint is a characteristic of Homo sapiens. Here the articular surface of one bone is saddle-shaped and that of other bone fits into saddle (each bone forming this joint have both concave and convex areas). It is a modified condyloid joint in which movement is somewhat more free. It is a biaxial joint that allows flexion, extension, abduction, adduction and circumduction. e.g. Carpometacarpellar joint between carpal (trapezium) and metacarpal of thumb.

Imagine.(Textbook Page No. 208)

Question 1 Maharashtra Board Solution

If your elbow joint would be a fixed type of joint and joint between teeth and gum would be freely movable.

Solution & Step-by-Step Answer:

Use your brain power.(Textbook Page No. 210)

Question 1 Maharashtra Board Solution

Why are warming up rounds essential before regular exercise?

Solution & Step-by-Step Answer:

Can you tell?(Textbook Page No. 211)

Question 1 Maharashtra Board Solution

Classify various types of joints found in human body. Present the information in the form of chart. Give example of each type.

Solution & Step-by-Step Answer:

i. A point where two or more bones get articulated is called joint or articulation or athrosis.
They are classified based on degree of flexibility or movement they permit into lastly synovial or freely movable or diarthroses type of joints.

ii. Synarthroses / fibrous joints / movable joints:
In this joint, the articulating bones are held together by means of fibrous connective tissue. Bones do not exhibit movement. Hence, it is immovable or fixed type of joint. Synarthroses are further classified into sutures, syndesmoses and gomphoses.

iii. Cartilaginous / slightly movable joints / amphiarthroses:
These joints are neither fixed nor freely movable. Articulating bones are held together by hyaline or
fibrocartilages. They are further classified as

iv. Synovial joints / freely movable joints / diarthroses:

g. The types of synovial joints are on follows:

1. Pivot joint: In this type of joint, the rounded or pointed surface of one bone articulates with a ring formed partly by another bone and partly by the ligament. Rotation only around its own longitudinal axis is possible. e.g. in joint between atlas and axis vertebrae, head turns side ways to form ‘NO’ joint.

2. BaIl and socket joint: The ball like surface of one bone fits into cup like depression of another bone forming a movable joint. Multi-axial movements are possible. This type of joint allows movements along all three axes and in all directions. e.g. Shoulder and hip joint.

3. Hinge joint: In a hinge joint, convex surface of one bone fits into concave surface of another bone. In most hinge joints one bone remains stationary and other moves. The angular opening and closing motion (like hinge) is possible. In this joint only mono-axial movement takes place like flexion and extension. e.g. Elbow and knee joint.

4. Condyloid joint: It is an ellipsoid joint. The convex oval shaped projection of one bone fits into oval shaped depression in another bone. It is a biaxial joint because it permits movement along two axes viz, flexion, extension, abduction, adduction and circumduction is possible. e.g. Metacarpophalangeal joint.

5. Gliding joint: It is a planar joint, where the articulating surfaces of bones are flat or slightly curved. These joints are non-axial because the motion they allow does not occur along an axis or a plane. e.g. Intercarpal and intertarsal joints.

Saddle joint: This joint is a characteristic of Homo sapiens. Here the articular surface of one bone is saddle-shaped and that of other bone fits into saddle (each bone forming this joint have both concave and convex areas). It is a modified condyloid joint in which movement is somewhat more free. It is a biaxial joint that allows flexion, extension, abduction, adduction and circumduction. e.g. Carpometacarpellar joint between carpal (trapezium) and metacarpal of thumb.

[Students are expected to prepare a chart on their own.]

Can you tell?(Textbook Page No. 211)

Question 1 Maharashtra Board Solution

Human beings can hold an object in a better manner than monkeys. Why?

Solution & Step-by-Step Answer:

[Note: Gorillas, chimpanzees, orangutans and some other variants of apes have opposable thumb.]

Internet my friend.(Textbook Page No. 211)

Question 92 Maharashtra Board Solution

Now a days we hear from many elderly people that they are undergoing knee replacement surgery. Find out why one has to undergo knee replacement; how it is carried out and how it can be prevented.

Solution & Step-by-Step Answer:

Knee replacement is done in following cases:

[Students are expected to find out more information about knee replacement on internet]

Find out.(Textbook Page No. 212)

Question 1 Maharashtra Board Solution

You must have heard of Sachin Tendulkar suffering from ‘tennis elbow’, a cricketer suffering from a disorder named after another game. Can common people too suffer from this disorder? Find out more information about this disorder.

Solution & Step-by-Step Answer:

[Students are expected to find more information about tennis elbow on their own.]

Previous Chapter

Chapter 15 Excretion and Osmoregulation

Chapter 16 Skeleton and Movement Solutions