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Plants: Cells, tissue
and organs
Plants: Transport
system and nutrition
Outline
1. Key concepts
2. Cells
Chloroplasts, Cell walls, and Central
Vacuole
3. Vegetative Tissues
4. Vegetative Organs: Roots, Stems, Leaves
5. Transport system and nutrition
6. Conclusions
Key Concepts:
1. There are three major categories of tissue systems
in these plants: ground, vascular, and dermal
2. Plants grow by way of mitotic cell divisions
3. Each growing season, shoots and roots lengthen
and thicken
4. Water absorbed from soil moves on up through
xylem and into leaves
5. By the energy-requiring process of translocation,
sucrose and other organics are distributed in the
plant
Vegetative Tissues
1. Dermal tissue:
A. Simple epidermis (a.
barrier b. reduce H2O loss)
B. Specialized
epidermal cells – guard cells in pairs, stoma (pl.
stomata) for gas exchange and H2O vapor out
C. Root hairs – absorption of H2O
2. Ground tissue: leaves – photosynthesis
other plant part –store water, structural support,
and store sugars in the form of starch
3. Vascular tissue: A. Xylem (Vessels and
Tracheids) : conducts water and dissolved
minerals
B. Phloem (Sieve tube elements, companion
cells) conducts dissolved sugars from leaves
Xylem
Phloem
A Plant
Vegetative Organs
1. Roots
a. Taproots vs. fibrous roots
b. Root functions-anchorage, absorption,
storage
c. Root tip structure: root cap, meristem,
elongation zoon and maturation zoon
d. cross section at the zoon of maturation:
epidermis, root hair, cortex (ground
tissue), endodermis, vascular cylinder
(pericycle, xylem and phloem)
Vegetative Organs
2. Stems
a. Stem functions-support for leaves,
conduction
b. Tissues: epidermis, cortex, vascular
bundles, pith
c. Monocot versus dicot stem structure
d. Secondary growth of woody stemsxylem rings and seasons
Vegetative Organs
3. Leaves
a. Leaf (Leaf components-blade and
petiole) functions:
Photosynthesis, Gas exchange,
Water transport
b. Leaf structure
1) Epidermis-cuticle and stomata
2) Mesophyll-palisade and spongy
3) Vascular tissue-veins
Plant growth
a. primary growth = elongation of
shoots & roots
b. secondary growth = thickening of
structures
Root tip
Root tip
Root tip
Xylem and Phloem
Monocot
stem
Dicot stem
Vascular
bundles
Stem
structure
Stem
Secondary growth
Year rings
Leaf structure
Leaf structure
A Maple leaf
The growth of plants
Transport system and nutrition
1. Vascular system:
Xylem - conducts water and dissolved minerals
Phloem - conducts dissolved sugars
2. Water movement
more than 90% of water not used in metabolic
activities
water needs:
a. replace water lost through stomata
b. to transport minerals
c. to maintain turgor
d. metabolic activities
Transport system and nutrition
2.
3.
Water movement
The lost of water through leaf is called transpiration
Transpirational flow of water – water pulled onto surface
of leaf from xylem by cohesion (water molecules stick to
each other), tension (ability to pull column of water
without breaking), and adhesion (water sticks to other
things)
Movement of sugar – translocation
from source to sink
source = source of photosynthesis products
(leaf & root)
sink = site where sugars are moved to (roots, fruits,
flowers, leaf buds)
Transpiration
Transpiration
In Conclusion
1. Plant growth originates at meristems
2. Stems function in support of upright growth and
in conducting substances through the plant body
by way of vascular bundles
3. Leaves contain veins and mesophyll between the
upper and lower epidermis
4. Roots absorb water and ions for distribution to
plant parts
In Conclusion
5. Distribution of water and mineral ions occurs
through xylem
6. Plants lose water through transpiration:
evaporation of water from leaves and other parts
exposed to air
7.
Plants distribute organic compounds through sieve tubes
8. The pressure flow theory states that
translocation is driven by differences in solute
concentration and pressure between source and
sink regions
See you later