2.3 Specialised Plant Cells

1. BIOLOGY PRESENTATION
2.3 SPECIALISED PLANT
CELLS
GROUP 1
TEAM MEMBER:
SASHI & BARAN
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3. Meristems
What is meristem?
A group of cells which retain the ability to divide by mitosis

5. Structure of Meristematic Cells
• Cells are small
• Thin walled
• A central large nucleus
• Dense cytoplasm with small vacuoles
• Rectangular shaped
• Closely packed with no intercellular air
spaces

6. Functions of Merismatic Cells
– Mitotic cell division happens in plant meristems, which are composed of a group of self-renewing stem cellsfrom which
most plant structures arise.
– The cells of the shoot and root apical meristems divide rapidly and are "indeterminate", which means that they are not
designed for any specific end goal.
– The Shoot Apical Meristem (SAM) gives rise to organs like the leaves and flowers, while the Root Apical Meristem (RA
M) provides cells for future root growth.
– Meristematic tissue has a number of defining features, including small cells, thin cell walls, large cell nuclei, absent or
small vacuoles, and no intercellular spaces.
– The apical meristem (the growing tip) functions to trigger the growth of new cells in young seedlings at the tips of roots
and shoots and forming buds.
– The apical meristem is organized into four meristematic zones: (1) central zone, (2) peripheral zone, (3) medullary me
ristem and (3) medullary tissue.

7. PLANT CELL STRUCTURE
central vacuole
nucleus
chloroplast
cell wall

8. GROUND TISSUE
Ground tissue fills the interior of the plant. It
contains three basic cell types:
- Parenchyma cells
- Collenchyma cells
- Sclerenchyma cells

9. PARENCHYMA
DEFINITION: Parenchyma is the bulk of a substance. In plants,
parenchyma is the ground tissue of nonwoody structures

10. PARENCHYMA
• CHARACTERISTICS
• least specialized cell type
• only thin primary cell wall
is present
• possess large central
vacuole

11. FUNCTIONS
• Parenchyma cells are loosely arranged many intercellular air
spaces
allows gaseous exchange
between plant tissues
and environment (stomata &
lenticles)
photosynthesis

12. • the cells are also important for food storage
starch grains,oil droplets,water & salts
- secrete subtances such as resins,tannins,hormone
s,enzymes & sugary nectar
- provide support & shape in plant when they are
tightly packed & turgid
- parenchyma cell in leaves contain chloroplasts to
carry out photosynthesis

13. Parenchyma

14. Modification of parenchyma cells
Modified
parenchyma cell
Structure Distribution Function
Epidermis -elongated &flattened
-does not contain
chloroplast
one cell thick - protection from lo
ss of water &
pathogens
Mesophyll - palisade is
column-shaped
-spongy is roughly
spherical
lies between
upper & lower ep
idermis of leaves
- large ntercellular
spaces between
SPC allow gaseous
exchange
Endodermis -elongated & flattened a single layer of
cells around the
vascular tissue
- forms a selective
barrrier for the
movement of water
& m.s
Pericycle -roughy spherical found between
the endodermis
& central vascular
tissue in roots
-produces lateral
roots & involved in
the 2ndary growth
of roots

15. The end