NCERT Class 9 Science Chapter 6 Tissues

Chapter 6 Tissues

Intext Question and Answers
Question 1: What is a tissue?
Answer: A group of cells that are similar in structure and/or work together to achieve a particular function forms a tissue.

Question 2: What is the utility of tissues in multi-cellular organisms?
Answer: In multi-cellular organisms, tissues are differentiated to carry out a specific function at a definite place which is known as the division of labour. For example, nerve cells form the nervous tissue that helps in the transmission of messages whereas muscular cells form muscular tissue that help in movement.

Question 3: Name types of simple tissues.
Answer: Simple tissue is of three types:
1. Parenchyma
2. Collenchyma
3. Sclerenchyma

Parenchyma is further divided into aerenchyma and chlorenchyma.

Question 4: Where is apical meristem found?
Answer: Apical meristem is present at the growing tips of stems and roots and increases the length of the stem and the root.

Question 5: Which tissue makes up the husk of coconut?
Answer: Sclerenchyma tissue makes up the husk of coconut.

Question 6: What are the constituents of phloem?
Answer: The constituents of phloem are:
→ Sieve cells
→ Sieve tubes
→ Companion cells
→ Phloem fibres
→ Phloem parenchyma

Question 7: Name the tissue responsible for movement in our body.
Answer: Muscular tissue is responsible for movement in our body.

Question 8: What does a neuron look like?
Answer: Neuron consists of a cell body, the axons and dendrites. Dendrites are the large number of extensions which looks like branches extending out from the cell body. Cell body consists of a nucleus and other cell organelles. An axon is a tube-like structure that carries an electrical impulse from the cell body to the structures at the opposite end of the neuron.

Question 9: Give three features of cardiac muscles.
Answer: The three features of cardiac muscles are:
1. The cardiac muscles are cylindrical, branched and uninucleate.
2. These muscles are involuntary muscles.
3. They show rhythmic contraction and relaxation throughout life.

Question 10: What are the functions of areolar tissue?
Answer: Areolar tissue are connective tissues which is found between skin and muscles, around blood vessels and nerves and in the bone marrow. It fills the space inside the organs, supports internal organs and helps in the repair of tissues.




Exercise Question and Answers
Question 1: Define the term “tissue”.
Answer: A group of cells that are similar in structure and/or work together to achieve a particular function forms a tissue.

Question 2: How many types of elements together make up the xylem tissue? Name them.
Answer: The xylem is made up of 4 elements:
→ Tracheids
→ Vessels
→ Xylem parenchyma
→ Xylem fibres

Question 3: How are simple tissues different from complex tissues in plants?
Answer:

Simple tissue	Complex tissue
Simple tissue is made up of one type of cell.	Complex tissue is made up of more than one type of cell.
Cells of this type are similar in structure and perform similar function.	Different types of cell perform different functions.
Example of simple tissues are parenchyma, collenchyma and sclerenchyma.	Example of complex tissues are xylem and phloem.

Question 4: Differentiate between parenchyma, collenchyma and sclerenchyma on the basis of their cell wall.
Answer:

Parenchyma	Collenchyma	Sclerenchyma
Has thin cell wall; cells are loosely packed.	Has cell wall which are irregularly thickened at the corners; very little intercellular space.	Has cell wall which are uniformly thickened; no intercellular space is present.
Cell wall is made of cellulose.	Cell wall is mainly made up of pectin and hemicellulose.	An additional layer of cell wall is found which is composed of lignin.

Question 5: What are the functions of the stomata?
Answer: The outermost layer of the cell, epidermis, has small pores here and there which are known as stomata. They are necessary for exchanging gases with the atmosphere. Transpiration (a process in which water is lost 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 muscles	Smooth muscles	Cardiac muscles
They are also called Skeletal muscles as they are mostly connected to bones and help in body movement.	They are found in alimentary canal, the bronchi of the lungs, in the iris of the eye, and in ureters.	They are found in heart.
They are voluntary muscles.	They are involuntary muscles.	They are involuntary muscles.
These cells are long, cylindrical, unbranched and multinucleate (with many nucleus).	These cells have pointed ends (spindle in shape) and are uninucleate (single nucleus).	These cells are cylindrical, branched and uninucleate.

Question 7: What is the specific function of the cardiac muscle?
Answer: Cardiac muscles cells are cylindrical, branched and uninucleate. They are involuntary muscles. They show rhythmically contraction and relaxation throughout life. Their rhythmic contraction and relaxation helps in pumping action of heart.

Question 8: Differentiate between striated, unstriated and cardiac muscles on the basis of their structure and site/location in the body.
Answer:

Striated muscle	Unstriated muscle	Cardiac muscle
On basis of structure:
Cylindrical	Long	Cylindrical
Not branched	Branched	Branched
Multinucleate	Uninucleate	Uninucleate
Colored alternate light and dark bands are present	There are no bands present	Faint bands are present
Its ends are blunt	Its ends are tapering	Its ends are wavy and flat
On basis of location:
These muscles are present in body parts such as hands, legs etc.	These muscles control the movement of food in the alimentary canal, helps in contraction and relaxation of blood vessels etc.	These muscles control the contraction and relaxation of heart.

Question 9: Draw a labelled diagram of a neuron.
Answer:

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) Tissue that forms the inner lining of our mouth: Squamous Epithelium
(b) Tissue that connects muscle to bone in humans: Tendons
(c) Tissue that transports food in plants: Phloem
(d) Tissue that stores fat in our body: Adipose tissue
(e) Connective tissue with a fluid matrix: Blood
(f) Tissue present in the brain: Nervous tissue

Question 11: Identify the type of tissue in the following: skin, bark of tree, bone, lining of kidney tubule, vascular bundle.
Answer:
→ Skin: Striated squamous epithelium
→ Bark of tree: Cork (which is a protective tissue)
→ Bone: Connective tissue
→ Lining of kidney tubule: Cuboidal epithelium tissue
→ Vascular bundle: Conducting tissue

Question 12: Name the regions in which parenchyma tissue is present.
Answer: Parenchyma is found in leaves, fruits and flowers.

Question 13: What is the role of epidermis in plants?
Answer: Epidermis performs the following function:
1. It protects all the parts of the plant.
2. 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 and invasion by parasitic fungi.
3. Epidermal cells of the roots, whose function is water absorption, commonly bear long hair-like parts that greatly increase the total absorptive surface area.

Question 14: How does the cork act as a protective tissue?
Answer: Cork acts as a protective tissue because its cells are dead and compactly arranged without intercellular spaces. They have deposition of suberin on the walls that make them impervious to gases and water.

Question 15: Complete the following chart:

Answer: