Transcript
PLANT TISSUESBio-Group
Overview■ A. Plant tissues: meristematic and permanent■
‣B. Meristematic ‣ a. epical, ‣ b. vascular cambium‣ c. cork cambium
■‣C. Permanent tissues‣ a. parenchyma, ‣ b. collenchyma‣ c. schlerenchyma‣ d. chlorenchyma
■‣D. Complex permanent tissues‣ a. vascular, ‣ b. dermal‣ c. ground tissues
■‣E. Transpiration and capillary action.
■
Meristematic and permanent tissues■ A meristem is the tissue in most plants containing undifferentiated cells
(meristematic cells), found in zones of the plant where growth can take place. Meristematic cells give rise to various organs of the plant and keep the plant growing.
■ Permanent tissues is the plant tissue that has completed its growth and differentiation and is usually incapable of meristematic activity.
Function■ Meristems are responsible for plant growth, regions where cells
continuously divide.■ Meristems are divided into apical, intercalary and lateral meristem.■ Apical and intercalary meristems are responsible for growth in length
(primary growth), while lateral meristem is responsible for growth in diameter (secondary growth)
Meristematic tissues:
Apical and Intercalary Meristem
■ Apical meristem is responsible for growth in length of most plants.■ It’s located at the tips of roots and stems of plants■ Some monocots (plants whose seeds contain one cotyledon) grow in
length via intercalary meristem.■ It’s located at the base of the stem of monocots, and appears as
nodes.■ It helps grass grow quickly after mowing.
Lateral Meristem
■ Gymnosperms (plants whose seeds aren’t protected by an ovary) and most dicots have lateral meristem
■ Lateral meristem increases the diameter of the plant’s stem and roots■ Lateral meristem has two types: vascular cambium and cork cambium■ Vascular cambium is located between xylem and phloem. It produces
more vascular tissue.■ Cork cambium is located outside the phloem, and it produces cork.■ Cork cells are dead cells that replace epidermis to provide protection
and prevent water loss
Permanent tissues:
These tissues derived from the meristematic tissues but their cells have lost the power of division & have attained their definite forms. Permanent tissues are classified into simple & complex tissues.
Permanent tissues are composed of cells which are structurally & functionally similar.
Simple Permanent tissues
Parenchyma
Schlerenchyma
Chlorenchyma
Collenchyma
aerenchyma
ParenchymaCharacteristic: cells remain alive at maturitythin-walled cellsisodiametric shape intercellular spaces widespread occurrence
in the plant body (leaves, root, stem)
Collenchyma
Characteristic: cells remain alive at
maturitycell walls are thickenedintercellular spaces absent
or very small Found in the peripheral
regions of stems and leaves
Sclerenchyma
■Characteristic: Mature sclerenchyma cells are dead Cells have thick secondary walls Found in shells and the outer hard
coat of many seeds
Summary
Chlorenchyma and aerenchyma ■ In leaves, they form the mesophyll and are responsible for
photosynthesis and the exchange of gases, parenchyma cells in the mesophyll of leaves are specialized parenchyma cells called chlorenchyma cells (parenchyma cells with chloroplasts)
Complex permanent tissues
Xylem Phloem
XylemNature-xylem is a vascular and composed of cells of four different types:
tracheids and vessels element (bounded by thick lignified. Vessels are very long tube-like structures formed by a row of cells placed end to end. They conduct water).
Functions-i. The main function of xylem is to carry water & minerals salts upward from
the root to different parts of shoots.ii. Since walls of tracheids, vessels of xylem are lignified, they give
mechanical strength to the plant body.
PhloemNature-Phloem is composed of following two types : 1.sieve tubes;2.companion cells; Functions-phloem transport photosynthetically prepared food materials from the leaves to the storage organs & later from storage organs to the growing regions of the plant body.
Dermal, Vascular and Ground tissues
How the plant transports water?
Transpiration and capillary action:Transpiration pulls water up a stem:
•the driving force of this process starts at the top of the shoot system
•transpiration occurs, loss of water lowers water potential between the cellulose fibers of the cell walls, and water quickly is replaced by capillary movement of water from neighboring cell walls, that also pull the water from other walls until the water is replaced by water from a xylem veinlet.
•as water is pulled out of xylem, the cohesion of water molecules pulls on the water in the xylem column like pulling of a rope, all the way to root cells which replace the water by absorbing it from the soil
Capillary action ■ Capillary action is part of the reason that water
rises in a plant stem and moves throughout the plant. The water enters the plant’s roots and moves to other parts of the plant through tiny tube-like structures called xylem. Xylem are part of the plants transpiration system, through which nutrients, including water, are transported throughout the plant.
1) The elongation of root and stem forms what is known as the......
A) initial plantB) protoplantC) primary plant bodyD) secondary growth
2) Internode elongation in corn results from the growth of....
A) intercalary meristemB) protodermC) procambiumD) cork cambium
3) The outward cell division of the root apical meristem produces the....
A) root hairsB) xylemC) branch rootsD) root capE) pith parenchyma
4) Which of the following is not a basic plant type?
A) pithB) ground tissueC) epidermisD) vascular tissueE) meristems
5) Gas exchange through the bark occurs through…..
A) stomataB) pitsC) lenticlesD) spiraclesE) micropyles
6) Mature sclerenchyma cells are……..
A) suberized and contain no living protoplastsB) thin walled and often contain chloroplastsC) lignified and contain living protoplastsD) suberized and contain living protoplastsE) lignified and contain no living protoplast
The EndThanks
top related