1. Plant Structure (Leaves, Stems, Roots)
Honors Biology

2. Plant Body Shoot system = leaves + stem Root system
Meristem = cells that divide for life of plant, can give rise to all plant structures
3 BASIC Organs
Roots
Stems
Leaves

3. 2 BASIC Systems
BOTH SYSTEMS DEPEND ON THE OTHER
Root System (roots) receive sugars and other nutrients from photosynthetic parts
Shoot System (leaves and stems) depends on water & minerals absorbed from the soil by roots.

4. Tissue Types in Vascular Plants
Dermal Tissue
Covers/ protects plant
Makes cuticle on stems/ leaves
Allows for better H2O absorption (root hairs)
Make guard cells
Vascular Tissue (xylem & phloem)
Transport and support
Throughout the plant
Called “veins” in leaves
Called the “stele” in stem or root
Ground Tissue
Between dermal and vascular tissues
Storage
Photosynthesis (makes sugars)
Support
Dermal
tissue
Vascular
Ground

5. Stoma = opening in the leaf for gas exchange, water evaporation
Plant Body-LEAF
Leaf = blade + petiole
Functions
Exposes surface to sunlight
Major site of photosynthesis
Conserves water
Provides for gas exchange
Transpiration-water movement throughout the plant; evaporation of water from plant leaves
Blade
Petiole
Stoma = opening in the leaf for gas exchange, water evaporation

6. Leaf Structure-Dermal layers
Cuticle-The thin waxy covering on the outer surface of the leaf has a thin waxy covering This layer's primary function is to prevent water loss within the leaf. (Plants that live entirely within water do not have a cuticle).
Directly underneath the cuticle is a layer of cells called the epidermis (upper and lower)

7. Leaf Tissues Mesophyll Veins
Ground tissue between upper and lower epidermis
Two types:
Palisade parenchyma (mesophyll) cells
Lots of chloroplasts in these cells
Most photosynthesis occurs here
Spongy parenchyma (mesophyll) cells
Lots of air spaces where O2 and CO2 circulate
Near stomata (Think: sponges have lots of air spaces)
Veins
Xylem and phloem are continuous from roots through stem to leaves

8. Vascular Tissue (Veins)
Transports materials in roots, stems, & leaves.
Xylem (dead cells-water conducting)
Carry water & minerals up from roots
Tube-shaped dead cells
Their walls are used as water pipes
Phloem (living cells-food conducting)
Carry nutrients (food) throughout plant
SUGARS (sucrose), amino acids….
Tube-shaped living cells

9. Stomata and Guard Cells
The underside portion of a leaf has stomata and is the site of transpiration (water loss) and gas exchange.
During the day, the stomata of most plants are open, allowing the CO2, necessary for photosynthesis. When the plant is full of water, the two guard cells plump up, opening the stoma. When the stomata are open, water evaporates from the leaves. When the plant is losing water from transpiration faster than it is gaining water at its roots, the guard cells deflate and close the stomata. With stomata closed, the plant may run low on CO2 for photosynthesis.
However, when the stomata is closed, the plant may run low on CO2. The stomata closes at night. Factors such as temperature, humidity, hormonal response, and amount of CO2 in the leaves signal the guard cells to open or close.

10. Stomata help regulate the rate of transpiration
Guard cells
2 cells on either side of stomata (surrounds stomata)
regulate water loss
What conditions will promote closing of guard cells?
Hot, dry, windy conditions

11. Stoma Opening/Closing

12. Plant Body- ROOTS Root Functions Anchors plant in soil
Takes up water and minerals from soil

13. & gymnosperms

14. Modified Roots Some plants have modified roots
Adventitious roots arise aboveground  spread over large areas
Storage roots hold “food”  called root tubers

15. Phloem transports sugar
Plant Body-STEM
Stem: series of nodes and internodes
Functions
Support for the plant body
Holds leaves up to light
Transports nutrients throughout plant
Xylem conducts water
and minerals
Phloem transports sugar

16. Division of Meristem Cells Causes Plant Growth
Apical Meristem
tips of root and shoot
increase in height
Lateral Meristem
cylinders within plant body
increase in width

17. Types of Meristems (like embryonic stem cells)
Apical meristems are located at the tips of roots and in the buds of shoots
elongate shoots and roots, a process called primary growth
Lateral meristems
add thickness ONLY to woody plants, a process called secondary growth

18. MONOCOT PLANTS vs. DICOT PLANTS
Monocots: grasses, lilies, orchids, corn, palms, onions
Dicots (aka-Eudicots): broadleaf trees, shrubs, most flowers, and vegetables.
Cotyledon=seed leaf