Tissues

Class 9 – NCERT Science Solutions

Intext Questions 1

Question 1

What is a tissue?

Answer

A group of structurally and functionally similar cells performing a particular function is called a tissue.

Question 2

What is the utility of tissues in multi-cellular organisms?

Answer

A group of cells that are similar in structure and/or work together to achieve a particular function forms a tissue. In multi-cellular organisms, tissues provide structural and mechanical strength and enables the division of labour. In such organisms, many tissues work together to form an organ and then an organ system.

Intext Questions 2

Question 1

Name types of simple tissues.

Answer

Types of simple tissue are:

1. Parenchyma
2. Collenchyma
3. Sclerenchyma

Question 2

Where is apical meristem found?

Answer

Apical meristem is present at the growing tips of stems and roots.

Question 3

Which tissue makes up the husk of coconut?

Answer

The husk of coconut is made of sclerenchymatous tissue.

Question 4

What are the constituents of phloem?

Answer

The constituents of phloem are:

1. Sieve cells
2. Sieve tubes
3. Companion cells
4. Phloem fibres
5. Phloem parenchyma

Intext Questions 3

Question 1

Name the tissue responsible for movement in our body.

Answer

Muscular tissue is responsible for movement in our body.

Question 2

What does a neuron look like?

Answer

A neuron cell looks like a tree. A neuron consists of a cell body with a nucleus and cytoplasm, from which long thin hair-like parts arises. Usually each neuron has a single long part (process), called the axon, and many short, branched parts (processes) called dendrites.

Question 3

Give three features of cardiac muscles.

Answer

Three features of cardiac muscles are:

1. They are cylindrical.
2. They are uninucleate.
3. They are branched.

Question 4

What are the functions of areolar tissue?

Answer

Following are the functions of areolar tissue:

1. It fills the space inside the organs.
2. It supports internal organs.
3. It helps in repair of tissues.

Exercises

Question 1

Define the term “tissue”.

Answer

A group of structurally and functionally similar cells performing a particular function is called a tissue.

Question 2

How many types of elements together make up the xylem tissue? Name them.

Answer

Four types of elements together make up the xylem tissue. They are:

1. Tracheids — They are thick walled and tubular dead cells. They transport water and mineral.
2. Vessels — They are tubular cells and transport water and mineral.
3. Xylem parenchyma — They store food.
4. Xylem fibres — They are supportive in function.

Question 3

How are simple tissues different from complex tissues in plants?

Answer

Simple tissues	Complex tissues
Simple tissues are made up of only one type of cell.	Complex tissues are made up of more than one type of cells.
Simple tissue helps in storage and provides structural support.	The main role of complex tissue is transportation.
Example : Parenchyma, Collenchyma, Sclerenchyma	Examples : Xylem and Phloem

Question 4

Differentiate between parenchyma, collenchyma and sclerenchyma on the basis of their cell wall.

Answer

Parenchyma	Collenchyma	Sclerenchyma
Thin cell wall	Cell wall with thickening at corners	Very thick lignified cell wall

Question 5

What are the functions of the stomata?

Answer

Following are the functions of the stomata:

1. Exchange of gases with the atmosphere occur through stomata.
2. Transpiration (loss of water in the form of water vapour) also takes place through stomata.

Question 6

Diagrammatically show the difference between the three types of muscle fibres.

Answer

Striated muscle	Smooth muscle	Cardiac muscle
Show alternate light and dark bands or striations	Do not show striations	Striation are present
Long, cylindrical	Long with pointed ends (spindle-shaped)	Cylindrical
Unbranched	Branched	Branched
Multinucleate	Uninucleate	Uninucleate

Question 7

What is the specific function of the cardiac muscle?

Answer

The specific function of the cardiac muscle is to contract and expand. They show rhythmic and involuntary contraction and relaxation throughout life enabling the heart to beat and pump blood to all parts of the body.

Question 8

Differentiate between striated, unstriated and cardiac muscles on the basis of their structure and site/location in the body.

Answer

	striated muscles	unstriated muscles	cardiac muscles
Structure	cylindrical, unbranched and multinucleate with light and dark bands	cells are long with pointed ends (spindle-shaped) and uninucleate	cylindrical, branched and uninucleate
location	Skeletal muscles	Oesophagus, iris of the eye, in ureters and in the bronchi of the lungs	Heart

Question 9

Draw a labelled diagram of a neuron.

Answer

Labelled diagram of a neuron is shown below:

Question 10

Name the following.

(a) Tissue that forms the inner lining of our mouth.

(b) Tissue that connects muscle to bone in humans.

(c) Tissue that transports food in plants.

(d) Tissue that stores fat in our body.

(e) Connective tissue with a fluid matrix.

(f) Tissue present in the brain.

Answer

(a) Squamous epithelium

(b) Tendons

(c) Phloem

(d) Adipose tissue

(e) Blood

(f) Nervous tissue

Question 11

Identify the type of tissue in the following: skin, bark of tree, bone, lining of kidney tubule, vascular bundle.

Answer

1. Skin — epithelial tissues
2. Bark of tree — cork (formed by secondary meristem)
3. Bone — Connective tissue (Bone cells are embedded in a hard matrix that is composed of calcium and phosphorus compounds.)
4. Lining of kidney tubule — Cuboidal epithelium (with cube-shaped cells)
5. Vascular bundle — Xylem and phloem (Complex permanent tissue)

Question 12

Name the regions in which parenchyma tissue is present.

Answer

The parenchyma tissue can be found in the leaf, fruits, as well as flowers. It is located beneath the epidermis.

Question 13

What is the role of epidermis in plants?

Answer

The primary role of epidermis in plants is protection. The entire surface of a plant has an outer covering epidermis. It protects all the parts of the plant. Epidermal cells on the aerial parts of the plant often secrete a waxy, water resistant layer on their outer surface. This aids in protection against:

• loss of water
• mechanical injury
• invasion by parasitic fungi

Question 14

How does the cork act as a protective tissue?

Answer

A strip of secondary meristem located in the cortex forms layers of cells which constitute the cork. Cells of cork are dead and compactly arranged without intercellular spaces. They also have a substance called suberin in their walls that makes them impervious to gases and water. This is how cork act as a protective tissue protecting the plants from any physical or mechanical injuries and pathogenic infection.

Question 15

Complete the following chart:

Answer

The completed chart is shown below: