Epidermis is important for plants due to the following reasons
(i) it gives protection
(ii) helps in gaseous exchange
(iii) checks water loss
(iv) root hairs arising from epidermis helps in absorption of water and minerals.

(a) __________ are forms of complex tissue.
Ans. Xylem and phloem
(b) __________ have guard cells.
Ans. Stomata
(c) Cells of cork contain a chemical called __________.
Ans. Suberin
(d) Husk of coconut is made of __________ tissue.
Ans. Sclerenchyma
(e) __________ gives flexibility in plants.
Ans. Collenchyma
(f) __________ and __________ are both conducting tissues.
Ans. Xylem; phloem
(g) Xylem transports __________ and __________ from soil.
Ans. Water; minerals
(h) Phloem transport __________ from __________ to other parts of the plant.
Ans. food; leaf

Parenchyma	Sclerenchyma
Parenchyma cells have thin primary cell walls and lack secondary cell walls	Sclerenchyma cells have both primary and secondary cell walls
Parenchyma cells easily allow molecules to enter into cells and expel substances easily from the cell.	Permeability of sclerenchyma cell is limited due to the presence of the secondary wall.
Parenchyma cells are well adapted for photosynthesis	Sclerenchyma cells have very low photosynthetic ability
Parenchyma tissue can store various products of the plant body, such as water, sugar, oil, etc.	Sclerenchyma tissue does not store anything.
Parenchyma cells can produce new cells by acting as a meristematic tissue.	Sclerenchyma cells do not produce new cells. Unlike parenchyma tissue, sclerenchyma tissue can provide elastic strength to plant body and synthesize lignin which hardens the plant body and prevents decay.

Epithelial tissues are the covering or protective tissues in the animal body. Epithelium covers most organs and cavities within the body and keep different body systems separate.

The skin, the lining of the mouth, the lining of blood vessels, lung alveoli and kidney tubules are all made of epithelial tissue.
Epithelial tissue cells are tightly packed and form a continuous sheet.
They have only a small amount of cementing material between them and almost no intercellular spaces.
The permeability of the cells of various epithelia play an important role in regulating the exchange of materials between the body and the external environment and also between different parts of the body.
Regardless of the type, all epithelia are usually separated from the underlying tissue by an extracellular fibrous basement membrane.

Epithelial tissues are of following types�
(1) Simple squamous epithelium
(2) Stratified squamous epithelium
(3) Columnar epithelium, and
(4) Cubodial epithelium.

(1)Simple squamous epithelial cells
Simple squamous epithelial cells are extremely thin and flat and form a delicate lining. The skin, oesophagus and the lining of the mouth are also covered with squamous epithelium.
These tissues differ in structure that correlate with their unique functions. For example, in cells lining blood vessels or lung alveoli, where transportation of substances occurs through a selectively permeable surface, there is a simple flat kind of epithelium. This is called the simple squamous epithelium.

(2) Stratified squamous epithelium
Skin epithelial cells are arranged in many layers to prevent wear and tear. Since, they are arranged in a pattern of layers,

(3) Columnar epithelial tissue

Where absorption and secretion occur, as in the inner lining of the intestine, tall epithelial cells are present. This columnar epithelium facilitates movement across the epithelial barrier. In the respiratory tract, the columnar epithelial tissue also has cilia, which are hairlike projections on the outer surfaces of epithelial cells. These cilia can move, and their
movement pushes the mucus forward to clear it. This type of epithelium is thus ciliated columnar epithelium.

(4)
Cuboidal epithelium forms the lining of kidney tubules and ducts of salivary glands, where it provides mechanical support. Epithelial cells often acquire additional specialisation as gland cells, which can secrete substances at the epithelial surface. Sometimes a portion of the epithelial tissue folds inward, and a multicellular gland is formed. This is glandular
epithelium

Give reasons for
(a) Meristematic cells have a prominent nucleus and dense cytoplasm but they lack vacuole.
Ans. Cells of meristematic tissue are capable of division. Hence, prominent nucleus and dense cytoplasm are present in these cells. Since these cells continuously undergo division hence they do not need to maintain a particular shape and store food. Due to this, vacuoles are not required in these cells.

(b) Intercellular spaces are absent in sclerenchymatous tissues.
Ans. Cell wall in sclerenchyma is lignified. Due to this, intercellular spaces are absent in sclerenchymatous tissues.

(c) We get a crunchy and granular feeling, when we chew pear fruit.
Ans. In a pear fruit, cells of scelerenhyma are small and called stone cells. We get the crunchy feeling due to these stone cells.

(d) Branches of a tree move and bend freely in high wind velocity.
Ans. Collenchyma is present at junction of a branch. Collenchyma provides rigidity with flexibility. Due to this, branches of tree move and bend freely in high wind velocity.

(e) It is difficult to pull out the husk of a coconut tree.
Ans. The husk of coconut tree is composed of sclerenhyma. Due this, the husk is very hard and is difficult to be pulled out.

Characteristics
a)
- Cells of cork are dead at maturity
- These cells are compactly arranged
- Cells do not possess intercellular spaces.
- Cells possess a chemical substances suberin in their walls
- They are several layers thick.

b) As plants grow older, a strip of secondary meristem replaces the epidermis of the stem. Cells cut on the outer side by this meristem are called cork.

c) They are protective in function for older stem/twigs/branches. They are impervious to gases and water.

Both xylem and phloem consist of more than one type of cells, which coordinate to perform a common function.

Xylem	Phloem
Xylem tissue helps in the transport of water and minerals.	Phloem tissue helps in the transport of food.
Water is transported upwards from roots to aerial parts of plants	Food is transported in both upward and downward directions.
Transport in xylem requires physical forces such as transpiration pull.	Transport of food in phloem requires energy inthe form of ATP.
Xylem is made up of three types of dead cells (vessels, tracheids, xylem fibres)	There are three types of living cells (sieve tube cells, companion cells and phloem parenchyma)

The loss of ability to divide by taking up a permanent shape, size and function is called differentiation