Plant Structure and Function: Cell, Tissues, and Organs

1. Unit 7Chapter 23Plant Structure and Function

2. Typical plant cell

3. Plant Tissues • 1) Dermal Tissue • For covering and protection, and controlling water loss • Examples: epidermis, including cuticle of leaves, guard cells & stomata

4. Plant Tissues • 2) Vascular tissue • For transport of food, minerals and water • Examples: • Xylem (for transporting upward from roots) • Phloem (for transporting downward from leaves) Phloem Xylem

5. Plant Tissues • 3) Ground tissue • For storage, food production, strengthening and support • Examples: cortex, pith, mesophyll cortex pith

6. Plant Tissues Apical Meristem of Shoot • 4) Meristematic tissue • For production of new cells • Examples: growing tips in roots and stems (shoots)

7. Roots • To anchor, absorb, and conduct • Types of root systems: • 1) taproot • One main root with branches • Ex: carrot • 2) fibrous • Many small branching roots • Ex: grass

8. Root Structure • 1) Root cap • Protective covering of root tip • 2) Apical Meristem • Region of cell division (where mitosis occurs)

9. Root Structure cortex • 3) Epidermis • May contain root hairs for increasing surface area • 4) Cortex • Ground tissue for storage of food and water

10. Root Structure • 5) Endodermis • Waterproof cells that control flow of water into vascular tissue • 6) Pericycle • Produces lateral roots

11. Root Structure • 7) Xylem (star-shaped center) • Transports water upward • 8) Phloem(between rays of star) • Transport food downward

12. Stems • To support, conduct, and store • Arrangement of Vascular Bundles: • Monocots • Randomly scattered • Dicots • Radially arranged Can you classify these stems?

13. Woody stems • Bark • Composed of cork, phloem, & vascular cambium • Wood • Composed entirely of xylem tissue • Contains annual growth rings • Pith(young stems) Pith

14. Pith

15. Translocation • The movement of sugars through the phloem, from the source (origin) to the sink (storage area, such as root or fruit)

16. Leaves • For photosynthesis and transpiration • 1) Blade (flat green portion) • Simple • One undivided blade • Compound • Blade divided into leaflets • 2) Petiole (stalk) • Contains vascular tissue, attaches to stem

17. Leaf structure • 3) Epidermis • Upper epidermis produces waxy cuticle to prevent water loss • Lower epidermis contains guard cells & stomata to control water loss cuticle

18. 4) Mesophyll Photosynthetic tissue made up of palisade & spongy cells 5) Veins Contains xylem & phloem cells Leaf structure

19. Transpiration • Evaporation of water through stomata • Plants lose 90% of the water they transport from the roots by transpiration. What happens to the other 10%? • When water enters the guard cells, pressure causes them to bow, opening the stoma • When water leaves the guard cells, pressure is lost and the cells come together, closing the stoma

20. Plant hormones • Like animals, plants produce hormones to regulate growth & development • Hormones are chemicals produced in one part and transported to another to effect a change • Examples of plant hormones are Auxin, Gibberellins, Cytokinins, & Ethylene (Without) (With) Gibberellin

21. Tropic responses in plants • Tropism is a plant’s response toward a stimulus, such as gravity (gravitropism), light (phototropism) or touch (thigmotropism) • Ex: phototropism is the growth of a plant toward light

22. Nastic responses in plants • Nastic movements are NOT dependent on the direction of the stimulus • For example: in a Venus’s fly-trap, the insect triggers sensitive hairs on the surface and the leaf snaps shut