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Chapter 01 Organisation of Plant Tissues and Growth
1.1
Organisation of Plant Tissues
1.1.1 Two types of plant tissue and their main functions
➀
➁
➂
2 types of plant tissues:
(i)
Meristematic tissues
➻ tissues that actively dividing through mitosis
(ii)
➻ matured tissues that have experienced or are experiencing
Permanent tissues
differentiation
3 types of permanent tissues:
(i) Epidermal tissues
(ii) Ground tissues
(iii) Vascular tissues
Epidermal tissues ➻ the outermost surface of stems, leaves and roots of young plant
Cuticle ➻ epidermal cell walls that exposed to the air
Characteristics of cuticle
•
Epidermal cell wall that has a waxy and waterproof layer
Function of cuticle
© Reduces loss of water through evaporation
© Protects the leaf from mechanical injuries and pathogens
Modified epidermal cells and their functions
Å Guard cells – To control the opening and closing of the stoma
Å Root hair cells – To increase the surface area of the root to absorb more water and
mineral salts
1
Typed by LBO@2023
➃
Ground tissues
(i) Parenchyma tissues
(ii) Collenchyma tissues
(iii) Sclerenchyma tissues
Types of Ground
Tissues
Living Cells /
Dead Cells
Parenchyma tissues
Collenchyma tissues
Simplest living cells &
do not undergo
differentiation
Living cells & flexible
when matured
Dead cells when they
are matured
Have cell wall thicker
than parenchyma
tissue but thinner than
sclerenchyma
Have the thickest cell
wall among the ground
tissues
Cell wall is thickened by
cellulose
Cell wall is not
uniformly thickened
with pectin &
hemicellulose
Cell wall is uniformly
thickened by lignin
1. Stores food
2. Undergo
photosynthesis
3. Gives support and
shape to herbaceous
plants
Gives mechanical
support to the young
plants, herbaceous
plant & non-woody
plants
Gives mechanical
support to the mature
plants
Thickness of Cell Have the thinnest cell
Wall
wall among the ground
tissues
Cell Wall
Thickening
Function
➄
Sclerenchyma tissues
Vascular tissues
(i) Xylem tissue
(ii) Phloem tissue
Xylem tissue is made up of xylem vessels &
tracheid
Characteristics of xylem tissues
• Dead cells & no cytoplasm
Adaptations of xylem tissues
P1 - The cell wall of xylem is thickening with lignin
E1 – To provide mechanical support to the plant
P2 - Xylem vessels that are elongated, hollow and connected to each other from its root to the
leaves
E2 - To transport water and mineral salt to all parts of a plant
2
Typed by LBO@2023
Phloem tissue is made up of companion cells & sieve tubes
Characteristics of sieve tubes
Sieve tubes are living cells & has cytoplasm & no any organelles (nucleus & ribosome) as they
decompose at maturity stage
Sieve tubes arranged from end to end forming elongated and continuous tube structures
Function of phloem
Þ To transport sugars produced from the photosynthesis from the leaves to storage organs
such as roots, fruits and tubers
3
Typed by LBO@2023
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