Transcript dokular - benanbiology

TISSUES
Plant cell types rise by mitosis from a meristem. A meristem may be defined as a
region of localized mitosis. Meristems may be at the tip of the shoot or root (a
type known as the apical meristem) or lateral, occurring in cylinders extending
nearly the length of the plant.
A cambium is a lateral meristem that produces
Plant tissues
(usually) secondary growth. Secondary growth
 Meristematic
produces both wood and cork (although from
tissues
separate secondary meristems).
Primary
Secondary
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Nonmeristematic
tissues
Ground
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Supportive
Secretory
Dermal
Vascular
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Meristematic cells have thin cell walls, rich in cytoplasm, their
vacuoles are small because they are young dividing cells, have
large nucleus but their total size is small.
Primary meristems can be found in root, shoot and branch tips.
They enable growth in the length of the plant. Caliptra in root
tip protects the dividing cells.
Secondary meristems can be found only in dicotyledones which
live for more than a year. They are responsible for growth in the
width of the plant. Cambium is between the xylem and phloem.
Cork cambium produces the cork layer which protects plant.
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Apical meristems
located at the tips of roots and shoots
supply cells for the plant to increase in length (grow up
for shoots and down for roots)
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growth in this direction is known as primary growth
primary growth found in herbaceous and woody plants
primary growth found in monocots and dicots
Lateral meristems
located near the periphery of the plant, usually in a
cylinder
supply cells for the plant to increase in girth
 growth in this direction is known as secondary
growth
 found in all woody and some herbaceous plants
 lateral meristems and secondary growth found only
in dicots
Plant
cells are formed at meristems, and then develop into cell
types which are grouped into tissues. Plants have only three
tissue types: 1) Dermal; 2) Ground; and 3) Vascular.
Plant tissues

Meristematic
tissues
 Primary
 Secondary
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Nonmeristematic
tissues
 Ground
 Dermal
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Supportive
Secretory
Vascular
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The ground tissue comprises the bulk of the
primary plant body. Parenchyma, collenchyma,
and sclerenchyma cells are common in the
ground tissue.
Dermal tissue is composed of epidermal cells,
closely packed cells that secrete a waxy cuticle
that aids in the prevention of water loss.
Vascular tissue transports food, water, hormones
and minerals within the plant. Vascular tissue
includes xylem, phloem, parenchyma, and
cambium cells(in dicotyledones”.
Plant tissues
Nonmeristematic
tissues
Ground
paranchyma
mesophyll(photosynthetic
paranchyma)
vascular paranchyma
paranchyma for storage
paranchyma for aeration
Supportive –
sclerenchyma
collenchyma
Secretory
Dermal-protective
Vascular
Paranchyma cells
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Least specialized plant cells
Thin and somewhat flexible cell walls
Living at maturity
Carry on most of the plant's metabolic functions
Generally have a large central vacuole
Most parenchyma cells have the ability to differentiate
into other cell types under special conditions
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During repair and replacement of organs after injury
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http://www.uic.edu/classes/bios/bios100/lectf03a
m/lect18.htm
Plant tissues
Nonmeristematic
tissues
Ground
paranchyma
Supportive –
sclerenchyma
collenchyma
Secretory
Dermal-protective
Vascular
Collenchyma cells
support the plant. These
cells are charcterized by
thickenings of the wall,
the are alive at maturity.
Sclerenchyma cells support
the plant. They often occur
as bundle cap fibers.
Sclerenchyma cells are
characterized by thickenings
in their secondary walls.
They are dead at maturity .
Plant tissues
Nonmeristematic
tissues
Ground
Supportive –
Secretory
Dermal-protective
Vascular
Specialized secretory parenchymal cells
are found lining resin ducts . For
attraction of birds and insects, for
protection, for healing
Plant tissues
Nonmeristematic
tissues
Ground
Dermal-protective
epidermis: The outermost layer (occasionally several layers) of
cells on the primary plant body. Doesn’t have
chloroplasts but they are living. Hair cells and stoma
are formed from the differentiation of epidermal
cells.
The epidermal tissue functions in prevention of
water loss and acts as a barrier to fungi and other
invaders. Thus, epidermal cells are closely packed,
with little intercellular space. To further cut down on
water loss, many plants have a waxy cuticle layer
deposited on top of the epidermal cells
periderm: The outer layers of tissue of woody roots and
stems, consisting of the cork cambium and the
Vascular
tissues produced by it, such as cork. It has lenticels
for gas exchange.
Plant tissues
Nonmeristematic
tissues
Ground
Dermal-protective The supporting and water-conducting tissue
Vascular
of vascular plants, consisting primarily of
Xylem: tracheids and vessels . It has one way of
flow direction. This tissue is nonliving and
has long hollow tubes.
The food-conducting tissue of vascular plants,
consisting of sieve tubes, fibers, parenchyma,
Phloem:
and sclereids . This tissue is composed of living
cells. It has 2 way flow of organic molecules like
aminoacids and glucose or sucrose.
Root
Dicotyledone stem
Monocotyledone stem
Monıocotyledones and dicotyledones
Monocotyledones
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Have 1 cotyledone
One piece of seed
Leaves are parallel
veined
The number of the
Petals of the flowers are
3 or multiples of the 3
Vascular tissue is
randomly scattered in
the stem.
Dicotyledones
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Have 2 cotyledones
2 piece of seed
Leaves are net veined
The number of the
petals of the flowers are
4 or 5.
Vascular tissue is lined in
a circle in stem.