NCERT solution of class 9 chapter tissues
Page
no. 69
Q 1: What is a tissue?
Ans 1: Tissue is a group of cells that are similar in structure and are organised
together to perform a specific task.
Q 2: What is the utility of tissues in multi-cellular organisms?
Ans 2: In unicellular organisms, a single cell performs all the basic functions
such as respiration, movement, excretion, digestion, etc.
But
in multicellular organisms, cells are grouped to form tissues. These tissues
are specialised to carry out a particular function at a definite place in the body.
For example, the muscle cells form muscular tissues which helps in movement,
nerve cells form the nervous tissue which helps in transmission of messages.
This is known as division of labour in multicellular organisms. It is because
of this division of labour that multicellular organisms are able to perform all
functions efficiently.
Page
no. 74
Q 1: Name types of simple tissues.
Ans 1: Simple permanent tissues are of three types: Parenchyma, Collenchyma, and
Sclerenchyma. Parenchyma tissue is of further two types - aerenchyma and
chlorenchyma.
Q 2: Where is apical meristem found?
Ans 2: Apical meristem is present at the growing tips of stems and roots. Their
main function is to initiate growth in new cells of seedlings, at the tip of
roots, and shoots.
Que 3: Which tissue makes up the husk of coconut?
Ans 3: The husk of a coconut is made up of sclerenchyma tissue.
Que 4: What are the constituents of phloem?
Ans 4: Phloem is the food conducting tissue in plants. It is made up of four
components:
(i)
Sieve tubes
(ii)
Companion cells
(iii)
Phloem parenchyma
(iv)
Phloem fibres
Page
no. 78
Q 1: Name the tissue responsible for movement in our body.
Ans 1: The muscular tissue is responsible for movement in our body.
Q 2: What does a neuron look like?
Ans 2: A neuron consists of a cell body with a nucleus and cytoplasm. It has two
important extensions known as the axon and dendrites. An axon is a long
thread-like extension of nerve cells that transmits impulses away from the cell
body. Dendrites, on the other hand, are thread-like extensions of cell body
that receive nerve impulses. Thus, the axon transmits impulses away from the
cell body, whereas the dendrite receives nerve impulses. This coordinated
function helps in transmitting impulses very quickly.
Q 3: Give three features of cardiac
muscles.
Ans 3: Three
features of cardiac muscles are:
(i)
Cardiac muscles are involuntary muscles that contract rapidly, but do not get
fatigued.
(ii)
The cells of cardiac muscles are cylindrical, branched, and uninucleate.
(iii)
They control the contraction and relaxation of the heart.
Q 4: What are the functions of areolar tissue?
Ans 4:
Functions
of areolar tissue:
(i)
It helps in supporting internal organs.
(ii)
It helps in repairing the tissues of the skin and muscles.
Exercise
Q 1: Define the term ‘tissue’?
Ans 1: The group of cells similar in structure that
work together to achieve a particular function forms a tissue. This group of
cells has a common origin.
Q 2: How many types of elements together make up
the xylem tissue? Name them.
Ans 2: Xylem is a complex tissue. It is made up of
following four kinds of cells or elements:
(a)
Tracheids
(b)
Vessels
(c)
Xylem parenchyma
(d)
Xylem fibres.
Q 3: How are simple tissues different from complex
tissues in plants?
Ans 3: Simple tissues are made up of one type of
cells which coordinate to perform a common function.
Complex
tissues are made up of more than one type of cells. All these coordinate to
perform a common function.
Question
4: Differentiate between parenchyma, collenchyma and sclerenchyma on the basis
of their cell wall.
Answer
4: The differences between cell walls of parenchyma, collenchyma and
sclerenchyma are given in the following table:
Qu 5: What are the functions of Stomata?
Ans 5: The small pores present in the epidermis of
the leaf are stomata. Stomata are enclosed by two kidney shaped cells called
guard cells.
Functions
of Stomata
Exchange
of gases, particularly CO2 and O2, with atmosphere.
Loss
of water in the form of vapour during transpiration.
Question 6: Diagrammatically show the difference between
the three types of muscle fibres
Ans; .
Ans; .
Q 7: What is the specific function of cardiac
muscle?
Ans 7: Cardiac muscles are involuntary muscles which
show characteristics of both smooth and striated muscles. These muscles occur
in the walls of the heart.
Functions
of Cardiac Muscles
Cardiac
muscles contract and relax rapidly, rhythmically and tirelessly throughout
life. They contract endlessly from early embryonic stage until death.
The
contraction and relaxation of heart muscles help to pump and distribute blood
to various parts of body.
Question 8: Differentiate between striated, unstriated
and cardiac muscles on the basis of their structure and site / location in the
body.
Answer 8:
Question 9; Draw a labelled diagram of neuron.
Answer 9:
Question
10:
Name
the following:
(a)
Tissue that forms 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 brain.
Answer
10:
(a)
Squamous epithelium
(b)
Tendon
(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 11:
Skin - Stratified Squamous epithelium
Bark of tree - Cork protective tissue
Bone - Connective tissue
Lining of kidney tubule - Cuboidal epithelium (Cuboidal epithelial tissue)
Vascular bundle - Complex permanent tissue (Xylem and Phloem)
Question 12: Name the regions in which parenchyma tissue
is present.
Answer 12: Parenchyma is a simple permanent tissue of
angiospermic plants. It is present in cortex and pith of stem and roots. It is
also present in mesophyll of leaves. When it contains chlorophyll, it is called
Chlorenchyma, found in green leaves.
Question 13: What is the role of epidermis in plants?
Answer 13: Epidermis is a protective tissue of
angiospermic plants. It provides protections to underlying tissues. Epidermis
forms outer covering of various plant organs such as roots, stem, leaves, and
flowers and remains in direct contact with the environment. Any substance
whether solid, liquid or gas can enter into the plant or move outside only
after passing through this layer. Epidermis helps in absorption, secretion,
gaseous exchange and transpiration. It helps in preventing the entry of
pathogens.
Question 14: How does the cork act
as a protective tissue?
Answer 14: The cork cells are dead cells and do not have
any intercellular spaces. The cell wall of the cork cells are coated with
suberin (a waxy substance). Suberin makes these cells impermeable to water and
gases. Cork is protective in function; it protects underlying tissues from
desiccation, infection and mechanical injury.
