Tissue is a group of structurally similar or dissimilar cells that perform a common function. Plant tissues are of two types based on the ability of their cells to divide, namely; meristematic tissue and permanent tissues.
The meristematic tissue is composed of immature and undifferentiated cells that are able to perform rapid cell division.
The permanent tissues are formed of cells that loss their ability to divide.
In plants, there are three types of meristematic tissues.
They are apical meristem, intercalary meristem and lateral meristem.
Apical meristems are located at root apex and shoot apex. The Intercalary meristems are located in the nodes or at the base of a leaf.Lateral meristems are present in the mature regions and along the lateral sides of the stem and the roots. Cambium and cork cambium are the types of lateral meristems.
There are two major types of permanent tissues, namely simple tissues and complex tissues.
The simple tissue is composed of only one type of cell that performs only one function while the complex tissues are heterogeneous and made up of different types of cell elements.
Simple tissues are of three types, namely; parenchyma, collenchyma and sclerenchyma.
The two main types of complex tissues are xylem and phloem.
Xylem is made up of four types of elements tracheids, xylem vessel, xylem fibres and xylem parenchyma.Phloem is made up sieve tubes, companion cells, phloem fibres and phloem parenchyma.
The xylem acts as a water conducting tissue, whereas the phloem acts as a food conducting tissue in plants.
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Distinguish between xylem tissue and phloem tissue.Marks:3
1. It consists of tracheids, vessels, xylem parenchyma and xylem fibres.
1. It consists of sieve tubes, companion cells, phloem fibres and phloem parenchyma.
2. Many cells of the xylem are dead cells. 2. It contains living cells except phloem fibres.
2. It conducts water and minerals from roots to aerial parts of the plant body.
2. It transports food from leaves to other parts of the plant.
What is the role of epidermis in plants?Marks:3
Epidermis plays a protective role. It protects all the external parts of the plant against loss of water, mechanical injury and invasion by parasites etc. Epidermal cells on the aerial parts of the plant often secrete a waxy layer which protects the plant surface from mechanical injury and water loss. Root hair present on epidermis of root help in absorption of water and mineral from soil.
How many types of elements together makeup the xylem tissue? Name them.Marks:2
Xylem is made of four types of elements -
(iii) Xylem fibres and
(iv) Xylem parenchyma
What are the constituents of phloem?Marks:2
The constituents of phloem are:
(i) Sieve tubes
(ii) Companion cell
(iii) Phloem parenchyma
(iv) Phloem fibre
Where is apical meristem found?Marks:1
Tips of stem and root.