Question

Design a concept map to explain the types of plant tissue.
Tissue, location Function, Structure, Permanent tissue, Merismatic tissue

Answer 1

Table of Contents

1 Plant Tissues2 Meristematic Tissue3 Permanent Tissue3.1 Simple Permanent Tissue3.1.1 Parenchyma3.1.2 Chlorenchyma3.1.3 Aerenchyma3.1.4 Collenchyma3.1.5 Sclerenchyma3.1.6 Epidermis3.2 Complex Permanent Tissue3.2.1 Xylem3.2.2 Phloem



Plant Tissues

Plants are stationary or fixed – they don’t move. Most of the tissues they have are supportive, which provides them with structural strength.Most of the plant tissues are dead, since dead cells can provide mechanical strength as easily as live ones, and need less maintenance.Animals on the other hand move around in search of food, mates and shelter. They consume more energy as compared to plants. Most of the tissues they contain are living.Another difference between animals and plants is in the pattern of growth. The growth in plants is limited to certain regions, while this is not so in animals.There are some tissues in plants that divide throughout their life. These tissues are localised in certain regions.Based on the dividing capacity of the tissues, various plant tissues can be classified as growing or meristematic tissue and permanent tissue.Cell growth in animals is more uniform. So, there is no such demarcation of dividing and non-dividing regions in animals.The structural organisation of organs and organ systems is far more specialised and localised in complex animals than even in very complex plants. This fundamental difference reflects the different modes of life pursued by these two major groups of organisms, particularly in their different feeding methods.Also, they are differently adapted for a sedentary existence on one hand (plants) and active locomotion on the other (animals), contributing to this difference in organ system design.

Meristematic Tissue

The growth of plants occurs only in certain specific regions. This is because the dividing tissue, also known as meristematic tissue, is located only at these points.Depending on the region where they are present, meristematic tissues are classified as apical, lateral andintercalary.New cells produced by meristem are initially like those of meristem itself, but as they grow and mature, their characteristics slowly change and they become differentiated as components of other tissues.



Apical meristem is present at the growing tips of stems and roots and increases the length of the stem and the root.The girth of the stem or root increases due to lateral meristem (cambium).Intercalary meristem is the meristem at the base of the leaves or internodes (on either side of the node) on twigs.As the cells of this tissue are very active, they have dense cytoplasm, thin cellulose walls and prominent nuclei. They lack vacuoles.

Permanent Tissue

What happens to the cells formed by meristematic tissue? They take up a specific role and lose the ability to divide. As a result, they form a permanent tissue.This process of taking up a permanent shape, size, and a function is called differentiation. Cells of meristematic tissue differentiate to form different types of permanent tissue.



Complex Permanent Tissue

The different types of tissues we have discussed until now are all made of one type of cells, which look like each other. Such tissues are called simple permanent tissue. Yet another type of permanent tissue is complex tissue.Complex tissues are made of more than one type of cells. All these cells coordinate to perform a common function.Xylem and phloem are examples of such complex tissues. They are both conducting tissues and constitute a vascular bundle.Vascular or conductive tissue is a distinctive feature of the complex plants, one that has made possible their survival in the terrestrial environment.



Xylem

Xylem consists of tracheids, vessels, xylem parenchymaand xylem fibres. The cells have thick walls, and many of them are dead cells.Tracheids and vessels are tubular structures. This allows them to transport water and minerals vertically.The parenchyma stores food and helps in the sideways conduction of water. Fibres are mainly supportive in function.

Phloem

Phloem is made up of four types of elements: sieve tubes, companion cells, phloem fibres and the phloem parenchyma. Sieve tubes are tubular cells with perforated walls.Phloem is unlike xylem in that materials can move in both directions in it. Phloem transports food from leaves to other Parts of the plant. Except for phloem fibres, phloem cells are living cells.


Hope this answer is helpful to you frnd....



Answer 2

Types of plant tissue

• A group of structurally similar or dissimilar cells that have a common origin and perform the same function is known as tissue.

• In plants, broadly two different types of tissues are found, (1) meristematic tissue & (2) permanent tissue.

MERISTEMATIC TISSUES:

• Meristematic tissue constitutes a group of immature cells that has the capacity for active cell division and re-division.

• The term "meristem" was coined by Nageli (1858).
• These tissues in plants are seen in the apex of the stem, root, leaf primordia, vascular cambium, cork cambium, etc.

• Absence of inter-cellular spaces. Cells found are always living and thin-walled. These are rich in the cytoplasm with minute vacuoles. They are diploid and show mitotic cell division.

• Cells lack reserve food materials, ER and plastids.

• Functions: Meristems refer to the actively dividing tissues of the plant.

• They are mainly responsible for primary growth (elongation) & secondary growth (thickness) of the plant.

• All new organs and their growth happen by the active division of meristems.

• Secondary tissues such as wood and cork are also formed due to meristematic activity.

• PERMANENT TISSUES: The tissues that have lost the capacity for growth and division temporarily or permanently are called permanent tissue.

• It results from the division and differentiation of the meristem.
• These tissues may be living or dead, thin (living tissue) or thick-walled (dead tissue).

TYPES: Permanent tissues are of two types- 1. Simple tissue 2. Complex tissue

• A simple tissue (homogeneous tissue) may be defined as a group of similar cells that perform a common function principally.
• These are classified into three groups namely (a) Parenchyma (b) Collenchyma (c) Sclerenchyma.

• Parenchyma: These are made up of isodiametric living cells which may be oval or rounded. Cells have intercellular spaces.

• Thin Cell wall and made up of hemicellulose and cellulose. Cells have dense and living protoplasm and may show meristematic activity.

• Location: Cortex, pith, mesophyll tissue, endosperm and also associated with xylem and phloem.

• Parenchyma mainly serves as storage tissue and is associated with functions such as regeneration, formation of the adventitious root, graft union etc.

• Specialised parenchyma i.e. Aerenchyma renders buoyancy, prosenchyma provides mechanical support, chlorenchyma helps in photosynthesis and idioblast stores ergastic substances.

• Collenchyma: It is living mechanical tissue. Cells are longer than parenchyma cells. Thick cell wall and made up of cellulose and pectin.

• The collenchyma gives tensile strength to the growing organs such as providing flexibility to the petiole of the leaf. It helps in photosynthesis.

• Sclerenchyma: These are hard, rigid and dead tissues. The deposition of lignin makes the cell wall very thick.

• It gives mechanical support as well as rigidity to plants.

• COMPLEX TISSUE: A group of different types of cells (heterogeneous) performing the same function is termed complex tissue/ vascular tissue.

• Xylem: It is the principal sap (water and minerals) conducting complex tissue of the plant.

• It is mainly associated with phloem and makes the vascular bundles.
• It is made up of 4 components:

• Tracheids: Elongated, narrow lumen cells with tapering ends make tracheids. Cell wall is of lignin and thickening may vary.

• Vessels: Vessels represent elongated, broad-ended, cylindrical elements with a wider lumen.

• Vessels contain lignified walls and thickening may be annular, spiral, scalariform or reticulate.

• Their cell wall possesses many bordered pits but the pits are smaller than those found in tracheids.

• The vessels possess perforated end walls known as perforated plates. It may be simple or multiple.

• Vessels develop hardwood or porous wood, Vessels with a narrow lumen are protoxylems and the wider lumen is known as a metaxylem.

• Xylem fibre: Dead sclerenchymatous cell in the xylem. They are long, narrow cells with thick lignified walls and tapering ends.

• Xylem parenchyma: Xylem or wood parenchyma represents the only living component of the xylem. It mainly helps to store starch and fats. Among these, only xylem parenchyma is living and the rest are non-living & dead.

• Tracheids and vessels help conduct water and minerals from the base to the top of the plants.

• Xylem parenchyma stores food. Xylem fibre helps in mechanical support.
• Phloem:- Sieve tubes: They form the conducting elements of phloem and are called collectively as sieve elements.

• Companion cells: These are elongated, narrow, thin-walled living cells associated with sieve tubes and are placed side by side with them The sieve tubes and companion cells are joined through pits.
• Companion cells help in food transportation along with sieve tubes.

• Phloem parenchyma: It is an elongated, pointed, living, thin-walled parenchymatous cell intermixed with sieve tube elements. It helps in the storage and conduction of food. It serves to provide mechanical support.

• Function: translocation of solute from source to sink of the plants.

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