Maharashtra Board Class 6th Chapter 8 Our Skeletal System and the Skin Solution

Textbook Questions and Answers

1. Fill in the blanks with the proper word. 

Question a.
The place where two or more bones are connected is called a …………… .
Answer:
joint

Question b.
Cells of epidermis contain a pigment called ………… .
Answer:
melanin

Question c.
…………… and ……………. are the two layers of the human skin.
Answer:
epidermis, dermis

Question d.
The human skeletal, system is divided into ………….. parts.
Answer:
two

2. Match the pairs.

Question a.

Column ‘A’	Column ‘B’
1. Ball and socket joint	a. Knee
2. Hinge joint	b. Wrist
3. Gliding joint	c. Shoulder

Answer:

Column ‘A’	Column ‘B’
1. Ball and socket joint	c. Shoulder
2. Hinge joint	a. Knee
3. Gliding joint	b. Wrist

3. Right or wrong? If wrong, write the correct sentence. 

Question a.
Bones are soft.
Answer:
Wrong: Bones are hard.

Question b.
The human skeleton protects the internal organs.
Answer:
Right

4. Put a [✓] mark at the proper places.

Question a.
The system which gives our body. a definite shape to
(a) Excretory system [ ]
(b) Respiratory system [ ]
(c) Skeletal system [ ]
(d) Circulatory system [ ]
Answer:
(c) Skeletal system [✓]

Question b.
The ………… joint is seen in fingers and toes.
(a) Hinge joint [ ]
(b) Ball and socket joint [ ]
(c) Immovable joint [ ]
(d) Gliding joint [ ]
Answer:
(a) Hinge joint [✓]

5. Answer the following questions in your words.

Question a.
What are the functions of your skin?
Answer:
The functions of the skin are :

1. Protects the internal parts of the body like muscles, bones, organ systems etc.
2. Help to preserve the moisture in the body.
3. Synthesizing Vitamin D.
4. Regulates body temperature by releasing sweat.
5. Gives protection from heat and cold.
6. Functions as the sensory organ of touch

Question b.
What should you do to keep the bones strong and healthy?
Answer:
To keep the bones strong and healthy:

1. We should include calcium and phosphrous rich food in our diet.
2. We also include vitamin D rich food in our diet.
3. We get these from milk, milk products, leafy vegetables, meat and exposure to sunlight.
4. We should exercise regularly.

Question c.
What are the functions of human skeletal system?
Answer:
The functions of human skeletal system are:

1. Gives a definite shape to the body.
2. Provides support to the body.
3. Protects the delicate organs inside the body.

Question d.
Which are the various reasons due to which our bones might break?
Answer:
The bones in our body might break due to:

1. Lack of calcium and phosphorous.
2. Due to fracture because of an accident or a fall.
3. Lack of proper nutrition.
4. Due to deficiency of Vitamin D.

Question e.
What are the different types of bones? How many types are there? Give example of each.
Answer:
There are four types of bones in our body:

Types of Bone	Example
1. Flat bones	Sternum in the chest
2. Small bones	Stirrup in each ear
3. Irregular bones	Vertebra posterior (back side) of the body
4. Long bones	Femur or thigh bone

Types of Bone Example

1. Flat bones Sternum in the chest
2. Small bones Stirrup in each ear
3. Irregular bones Vertebra posterior (back side) of the body
4. Long bones Femur or thigh bone

6. What will happen if?

Question a.
There are no joints in our body.
Answer:
If there are no joints in our body, we will be standing like a tree without any movement, we can move only because of joints.

Question b.
There is no melanin pigment in our body.
Answer:
We will not have protection from ultraviolet rays. Our skin will become whitish.

Question c.
Instead of 33 vertebras in our body, we had one single and straight bone.
Answer:
We cannot bend down at our will.

7. Draw diagrams.

Question a.
Types of joints.
Answer:

Question b.
Structure of skin
Answer:

Activity:

Question 1.
Collect pictures of the different parts of the human skeletal system and paste them on chart paper. Write the functions of
each, too.

Question 2.
Collect the pictures, newspaper cuttings, etc. which show the skeletal systems of various animals and observe the differences between them.

Important Questions and Answers

Choose the correct alternative:

Question 1.
The ………………….. protects the brain.
(a) skull
(b) rib cage
(c) spine
(d) none of above
Answer:
(a) skull

Question 2.
X-rays were discovered by …………………..  .
(a) Sir C.V.Raman
(b) Galileo
(c) Sir Isaac Newton
(d) Roentgen
Answer:
(d) Roentgen

Question 3.
The bones of ………………….. are immovable.
(a) hand
(b) leg
(c) spine
(d) skull
Answer:
(d) skull

Question 4.
We can move the bones of ………………….. in a 360° angle.
(a) elbow
(b) knee
(c) shoulder
(d) wrist
Answer:
(c) shoulder

Question 5.
Our body temperature usually remains constant at ………………….. °C.
(a) 32
(b) 35
(c) 37
(d) 40
Answer:
(c) 37

Question 6.
The part of the skin which maintains body temperature is ………………….. .
(a) Epidermis
(b) Dermis
(c) Subcutaneous layer
(d) Network of blood vessels and nerve fibers
Answer:
(c) Subcutaneous layer

Fill in the blanks:

Question 1.
Except for the …………….., none of the bones of the skull can move.
Answer:
lower jaw

Question 2.
The spinal cord originates from the …………… .
Answer:
brain

Question 3.
The longest and the strongest bone in the human body is …………… .
Answer:
femur

Question 4.
…………….. is the smallest bone in our body.
Answer:
stirrup

Question 5.
The vertical, flat bone in the chest is called the ……………… .
Answer:
sternum

Question 6.
The …………… joint moves in a 180° angle.
Answer:
hinge

Match the columns:

Question 1.

Column ‘A’	Column ‘B’
1. Skull	a. 25 bones
2. Rib cage	b. 6 bones
3. Spine	c. 22 bones
4. Both ears	d. 33 bones

Answer:

Column ‘A’	Column ‘B’
1. Skull	c. 22 bones
2. Rib cage	a. 25 bones
3. Spine	d. 33 bones
4. Both ears	b. 6 bones

Question 2.

Column ‘A’	Column ‘B’
1. Lower jaw	a. Movable joint
2. Ears	b. Femur
3. Thigh	c. Movable joint in skull
4. Elbow	d. Smallest bone

Answer:

Column ‘A’	Column ‘B’
1. Lower jaw	c. Movable joint in skull
2. Ears	d. Smallest bone
3. Thigh	b. Femur
4. Elbow	a. Movable joint

Right or Wrong? If wrong, write the correct answers:

Question 1.
The spine is a part of the appendicular skeleton.
Answer:
Wrong: The spine is a part of the axial skeleton.

Question 2.
Ankle joints are gliding joints.
Answer:
Right

Question 3.
All the skull joints are immovable.
Answer:
Wrong: Except lower jaw, all the skull joints are immovable.

Question 4.
The skin maintains normal body temperature.
Answer:
Right

Answer in one word:

Question 1.
The part which protects the heart and lungs.
Answer:
Rib cage

Question 2.
Ali falls down and his elbow is broken.
Answer:
Fracture

Question 3.
The image which spots the broken bone.
Answer:
X-ray

Question 4.
The biotic component of our body.
Answer:
Bone cell

Question 5.
The part which protects the vertebral column.
Answer:
Spine

Question 6.
The part which connects the bone in our body.
Answer:
Ligament

Question 7.
The organ which helps us to sense whether something is hot or cold.
Answer:
Skin

Question 8.
The pigment which gives colour to the skin.
Answer:
Melanin

Can you tell?

Question 1.
What is a fracture? How will you help a friend who has met with an accident and fractured his leg?
Answer:
Fracture is a crack or break in a bone. Fracture may occur due to accident or fall from height or injury. If my friend’s leg is fractured, then. I would –

1. Ask him to prevent any movement of the fractured part.
2. Get immediate medical help.
3. Take the x-ray image of the fractured or swollen part.
4. An x-ray image shows the exact spot where the bone is broken. This will help in providing proper treatment.

Question 2.
What are the properties of bones?
Answer:
The properties of bones are:

1. Bones are hard and not flexible.
2. Bone cells are composed of two main constituents:
   • Bone cells are biotic components.
   • Calcium carbonate, calcium phosphate, minerals and salts are abiotic components.
3. Calcium imparts strength to bones.
4. As we grow the size and length of bones increases upto a certain limit.

Question 3.
What is human skeletal system? How is it divided?
Answer:

1. All the bones together form a framework or a skeleton.
2. All the bones of the body along with cartilage together form the skeletal system.
3. The human skeletal system can be divided into two parts – the axial skeleton and the appendicular skeleton.
4. The axial skeleton consists of the skull, the spine and the rib cage. These are situated symmetrically along the central axis.
5. The appendicular skeleton consists of the bones of arms and legs on either side of the central axis.

Question 4.
What is a joint? What are it’s types?
Answer:
Joints are places where two or more than two bones are connected to each other.

Question 5.
Describe the structure of skin.
Answer:

1. Human skin is made up of two main layers- outermost layer, epidermis and layer below it called dermis.
2. Below dermis there is a network of blood vessels and nerve fibers.
3. Under this layer there is a subcutaneous layer, which maintains body temperature.
4. The epidermis has various layers.
5. There are sweat glands in the skin which secrete sweat.

Question 6.
Write a short note on melanin.
Answer:

1. Melanin is a pigment present in the cells of epidermis.
2. Melanin is synthesized in certain glands in the skin.
3. The percentage of melanin decides the fairness or darkness of the skin.
4. Melanin protects our skin and the inner parts from ultraviolet sunrays.

Use your brain power!

Question 1.
Which colour of the skin will give greater protection from sun’s rays?
Answer:
Darker colour will give greater protection.

Give scientific reasons:

Question 1.
We are able to bend down at our will.
Answer:

1. 33 bones of the spine are placed straight one above the other.
2. They are arranged flexibly.
3. Their flexibility allows us to bend down at our will.

Question 2.
Calcium is an important mineral.
Answer:

1. Calcium imparts strength to our bones.
2. If we are calcium deficient, possibility of bone fracture during a fall or an accident increases.
3. Hence, calcium is an important mineral.

Question 3.
Sweating helps to lower the body temperature.
Answer:

1. In the hot sun, the temperature of the skin rises.
2. The sweat is released.
3. The heat required for the evaporation of sweat is drawn from the body itself.
4. Hence, sweating lowers the body temperature.

Question 4.
Some people have jet black hair, while others have brown or reddish hair.
Answer:

1. It is melanin that determines the colour of our hair.
2. Jet black hair is due to pure melanin.
3. Brown hair is due to sulphur in the melanin.
4. Reddish hair is due to iron in the melanin.

Question 5.
Observe and discuss:
Your grandmother has wrinkles on her skin.
Answer:

1. As we grow older, the proportion of fat beneath the skin reduces.
2. However, previously tout skin does not shrink.
3. This causes wrinkles on the face of older people.

What will happen if:

Question 1.
If skin had no sweat glands.
Answer:
Skin regulates body temperature by releasing sweat. If skin had no sweat glands then we will not be able to maintain our body temperature at a constant 37°C.

Can you recall?

Question 1.
Which organ help us to sense whether something is hot or cold, rough or smooth, etc?
Answer:
The skin functions as the sensory organ of touch.

Question 2.
What happens when we walk or play in the hot sun?
Answer:
When we walk or play in the sun, we get tired, our skin secrete sweat.

Observe the figure and label as directed.

Question 1.

In the above figure label the parts marked a, b, c, d, e and hence show axial and appendicular
skeleton.
Answer:
(a) Skull
(b) Rib cage
(c) Spine
(d) Arm
(e) Leg
Axial skeleton: skull, the spine and rib cage
Appendicular: legs, arms

Question 2.

In the given figure, name the type of bones marked a, b, c, d. State where they are seen in our body.
Answer:
(a) Flat bones – rib cage and gliding joint
(b) small bones – finger
(c) Irregular bones – vertebal column
(d) Long bones – legs, arms