This document provides information about plant tissues. It discusses the two main types of plant tissues - meristems and permanent tissues. Meristems are tissues with cell division abilities and include apical, lateral, and intercalary meristems. Permanent tissues do not divide and include simple tissues like parenchyma, collenchyma, and sclerenchyma, as well as complex tissues like xylem and phloem. It also describes the functions and characteristics of epidermis, cork, and other specific plant tissue types. Various activities provide examples and questions to test understanding of plant tissue organization and functions.
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PLANT TISSUE
1. Tissue is a group of cells having similar origin,
structure& function. Study of tissues is called Histology
2. In unicellularorganism (Amoeba) single cell performs
all basic functions, whereas in multi-cellularorganisms
(Plants and Animals) shows divisionof laboras Plant
tissue& Animal tissues.
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Plant tissues are two types: Meristems & Permanent tissues.
Meristems: The Meristems are the tissues having the power of
cell division.It is found on those regions of the plant which
grows
Types of Meristems;
1. The Apical meristems– It is present at the growing tip of the
stem and roots and increases the length.
2. The lateral meristems - present at the lateralside of stem
and root (cambium) and increase the girth.
3. The intercalary meristems - present at internodes or base of
the leaves and increase the length between the nodes.
Permanent tissues: Two types such as Simple permanent
tissues & Complexpermanent tissues.
a) Simple permanent tissues: subdividedas
(i): Parenchyma: Tissues provide the support to plants. They
are loosly packed and have large intracellularspace.
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- Parenchyma with chlorophyllwhich performs photosynthesis
is called as chlorenchyma.
- The parenchyma with large air spaces to give buoyancyis
called as aerenchyma.
Parenchyma also stores food and water.
(ii) Collenchyma: Tissue provides mechanicalsupport,
thickened at the corners, have very little intercellularspace. It
allowseasy bending of various parts of plants without breaking
(iii) Sclerenchyma:Tissue makes the planthard and stiff,
thickened due to lignin and no intercellularspace.
Cells of this tissue are dead and commonly seen in the husk of
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coconut.
(iv) Guard cells and epidermal tissue: The tissue aidsin
protection and exchange of gases. Guard cells kidney shaped in
dicots, dumb bell shaped in monocots to guard the stomata.
The epidermaltissues of roots aid in absorptionof water and
minerals.
The epidermaltissues in desert plantshave a thick waxy coating
of Cutin with waterproof quality.
The epidermaltissues form the several layer thick Cork or the
Bark of the tree.
Epidermis: Epidermis forms one cell thick outermost layer of
various body organs of plants such as leaves, flowers, stems and
roots.
Epidermis is covered outside by cuticle. Cuticle is a water proof
layer of waxy substance called as cutin which is secreted by the
epidermal cells. Cuticle is very thick in xerophytes.
Cells of epidermis of leaves are not continuous at some places
due to the presence of small pores called as stomata. Each stoma
is guarded by a pair of bean shaped cells called as guard cells.
These are the only epidermal cells which possess chloplasts, the
rest being colorless.
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Functions :
(i) The main function of epidermisis to protect the plant from
desiccation and infection.
(ii) Cuticle of epidermis cuts the rate of transpiration and
evaporationof water and prevents wilting.
(iii) Stomata in epidermis allow gaseous exchange to occur
during photosynthesisrespiration.
(iv) Stomata also helps in transpiration.
Cork or phellem : in older roots and stems, tissues at the
periphery become cork cells or phellem cells.
Cork is made up to dead cells with thick walls and do not have
any intercellular spaces. The cell walls in cork deposit waxy
substance called as suberin.
The cells of cork become impermeable to water and gasses due
to the deposition of suberin. The cork cells are without any
protoplasm but are filled with resins or tannins.
Functions:
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(i) Cork is protective in function. Cork cells prevent desiccation,
infection and mechanical injury.
(ii) Imperviousness, lightness, toughness, compressibility and
elasticity make the cork commercially valuable.
(iii) Cork is used for insulation, as shock absorber in linoleum.
(iv) Cork is used in the making of a variety of sport goods such
as cricket balls, table tennis, shuttle cocks, wooden paddles etc.
b) Complex permanent tissues: The complex tissues are made
of more than one type of cells. All these cells coordinateto
perform a common function.
They are subdividedas;
Xylem: It consists of tracheids, vessels, xylem parenchyma and
xylem fibers. The cells have thick walls,
Function - aids in conduction of water and minerals.
Phloem: It consists of sieve tubes, companioncells, phloem
parenchyma, and phloem fibers.
Function - Phloem transports food material to other parts of
the plants..
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ACTIVITY.
Plant Tissue Systems;
The tissues of a plant are organized into three tissue systems:
the dermal tissue system, the ground tissue system, and the
vascular tissue system.
Use information from the table to answer the questions below it.
Tissue
System
and Its
Functions
Component
Tissues
Location of Tissue
Systems
Dermal
Tissue
System
• protection
• prevention
of water loss
Epidermis
Periderm (in
older stems
and roots)
Ground
Tissue
System
•
photosynthesis
• food storage
• regeneration
• support
• protection
Parenchyma
tissue
Collenchyma
tissue
Sclerenchyma
tissue
Vascular
Tissue
Xylem tissue
Phloem tissue
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System
• transport of
water and
minerals
• transport of
food
1. Where is the vascular tissue system located in
roots?
2. Where is the ground tissue system located in a
(dicots) stem?
3. What type of tissue are the veins in leaves?
4. Name three tissues in the ground tissue
system.
Activity:
Basic Plant Structure
Plants have three vegetative organs: roots, stems,
and leaves.
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Use information from the illustration to answer the
questions below.
1. Which part of
the leaf has the
main function to
carry out
photosynthesis?
2. The petiole is
part of which plant
organ?
3. Where on the
stem are the
axillary buds
attached?
4. From what plant
part does the shoot
develop?
Activity:
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Ground Tissues
The three types of ground tissue, parenchyma, collenchyma, and
sclerenchyma, function in photosynthesis, storage, regeneration,
support, and protection.
Use information from the table to help answer the questions below it.
Ground
Tissue
Parenchyma Tissue Collenchyma
Tissue
Sclerenchyma
Tissue *
Function • Photosynthesis
• Food storage
• Healing and tissue
regeneration
• Support in young
stems, roots, and
petioles
• Rigid support
• Protection
Cell Types
in This
Tissue
Parenchyma cells Collenchyma cells Sclereid cells &
fiber cells
*Some texts include tracheids and vessels as components of sclerenchyma
tissue.
1. Potatoes contain food in the form of starch, which ground tissue are
you eating when you eat mashed potatoes?
2. The part of rhubarb that people eat is the petiole of a large leaf. Which
tissue provides support for rhubarb?
3. Which ground tissue is a major component of the blades of spinach
leaves?
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4. Which ground tissue makes the shell of a nut hard?
ACTIVITY:
Vascular Tissues
Vascular tissue is composed of xylem and phloem, which function in the
transport of water and dissolved substances.
Use the information in the table to help answer the questions below it.
Vascular
Tissue
Xylem Tissue Phloem Tissue
Function • Conduct water and dissolved
minerals
• Support
• Conduct food and
other organic substances
Cell Types
Unique to This
Tissue
Tracheids Vessel members Companion
cells
Sieve-tube
elements
Additional Cell
Types in This
Tissue
Parenchyma cells
Fibers
Parenchyma cells
Fibers
1. Which tissue is most likely to transport dissolved sugar?
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2. What tissue transports water through dead cells?
3. Companion cells are unique to which tissue?
4. Vessel members are unique to which tissue?
ACTIVITY :
Primary Growth of Stems
The apical meristem produces the three primary meristems, protoderm, procambium, and
ground meristem, which develop into dermal tissues, vascular tissues, and ground tissues
respectively.
Use the information in the illustration to help answer the questions below it.
1. Xylem and phloem tissues are derived from which primary meristem?
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2. What is the dermal tissue called that is found in young stems and roots?
3. From which primary meristem is the epidermis derived?
ACTIVITY:
Primary Growth of Roots
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In roots, the three primary meristems, protoderm, procambium,
and ground meristem, develop from the apical meristem and
differentiate into epidermis, vascular tissues, and ground tissues.
Label the longitudinal section of a root below. On the left, label the regions in which cell
division, cell elongation, and cell differentiation take place. On the right, label the apical
meristem, the three primary meristems, and the three primary tissues. Click on the Check
Your Answers button to compare your answer with the correct answers.
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EXERCISE:
1. Primary tissues arise:
a.
during secondary growth
b.
from the three primary meristematic tissues
c.
from the vascular cambium
d.
from the cork cambium
e.
from two of the above
2. Secondary growth:
a.
occurs in all angiosperms
b.
is accomplished by the procambium
c.
is accomplished, at least in part, by the vascular cambium
d.
brings about an increase in the height of the plant
e.
results in the formation of the endodermis
3. The tissue most likely to provide flexible support is the:
a.
epidermis
b.
sclerenchyma
c.
parenchyma cell
d.
collenchyma
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e.
cambium
4. Cells which are typically in xylem but not in other plant tissues are:
a.
tracheids
b.
vessel elements
c.
both tracheids and vessel elements
d.
neither tracheids nor vessel elements
e.
companion cells
5. The secondary cell walls of adjacent cells:
a.
lie in direct contact with one another
b.
are separated from one another by the middle lamella
c.
are separated from one another by the primary walls and the middle lamella
d.
are formed following the death of the cells
e.
play no significant role in cell function
6. Mature sieve-tube members lack:
a.
cell walls
b.
cell membranes
c.
cytoplasm
d.
nuclei
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e.
sieve plates
7. The increase in diameter of the trunk of a tree is produced primarily by the:
a.
apical meristem
b.
cork cambium
c.
pith
d.
vascular cambium
e.
cork
8. In a three-year-old stem, the oldest secondary xylem is found:
a.
adjacent to the pith
b.
just inside the vascular cambium
c.
just outside the vascular cambium
d.
immediately adjacent to the primary phloem
e.
immediately adjacent to the secondary phloem
9. In a twenty-year-old woody stem:
a.
the most abundant tissue would be the secondary xylem
b.
the most abundant tissue would be the secondary phloem
c.
secondary xylem and secondary phloem would be equally abundant
d.
the most abundant tissue would be the cork
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e.
the oldest vascular cambium would be inactive
10. The tissue formed on the outside of a woody stem is called:
a.
bark
b.
cork
c.
cortex
d.
secondary phloem
e.
endodermis
11. Root hairs:
a.
are multicellular filaments
b.
are epidermal cells
c.
arise from the endodermis
d.
function in support
e.
two of the above
12. The apical meristem in the root:
a.
is located behind the root cap
b.
produces cells which become incorporated into the root cap
c.
gives rise to the primary meristematic tissues
d.
is a region of active cell division
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e.
all of the above
13. In a young root, the sequence of tissues from the outside to the center is:
a.
epidermis, pericycle, cortex, endodermis, primary phloem, primary xylem
b.
epidermis, cortex, endodermis, pericycle, primary phloem, primary xylem
c.
epidermis, cortex, primary phloem, primary xylem, endodermis, pericycle
d.
epidermis, primary phloem, cortex, primary xylem, endodermis, pericycle
e.
epidermis, cortex, pericycle, endodermis, primary phloem, primary xylem
14. In the root, the pericycle:
a.
is a single layer of cells just inside the epidermis
b.
arises from the ground meristem
c.
arises from the procambium
d.
is situated between the primary xylem and primary phloem
e.
regulates the movement of materials into the vascular tissue
15. The structure in the leaf that regulates water loss and gas exchange is the:
a.
cuticle
b.
epidermis
c.
palisade mesophyll
d.
spongy mesophyll