2. Introduction to Plants Chapter 22.1

3. Basic Plant Structure

4. Plants Are… 1) Multicellular 2) Eukaryotic 3) Autotrophic 4) Use Chlorophyll a or b

5. How Did Plants Originate?  First land plants appeared 500 mya  Resembled present day mosses  Released nitric acids on rock surfaces which created soil  Likely colonies of protists adapted to dry environment…but how?

6. Links Between Algae and Plants  Both have protective cell walls  Both contain chlorophyll used in photosynthesis  Both store food in the form of starches

7. Plants Must Adapt To Live On Land 1. Absorb nutrients from surroundings 2. Prevent desiccation 3. Reproduce without the aid of water  If plants adapt to these strategies, they can evolve on land  Why would a plant “want” to move onto the land?

8. A. Preventing Water Loss  Cuticle: waxy coating that prevents tissues from drying out  Stomata-openings in the cuticle that allow gas exchange to take place and also regulate water loss

9. Prevent Desiccation?  Desiccation= Drying Out  As plants evolved further away from water, they needed to evolve a waterproof structure/coating (cuticle)  But, this structure needs pores (stomata)  WHY?  Think about what the plant needs for photosynthesis…  CARBON DIOXIDE!

10. Stomata

11. B. Autotrophic  Leaf-organ that enables the plant to trap and absorb light energy

12. Leaf Layers via microscope

13. C. Stabilization and Nutrient Absorption (Accomplished with roots and mycorrihizea)  Roots-organ that is used to reach and transport water and minerals, anchor plants and store food  Earliest roots are rhizoids  Fossils show fungi “helped” plants before roots evolved

14. The Root  Main function = absorb water  Functional Part = root hair  Structure from outside in: –Epidermis with root hair= protection –Cortex=support/storage –Vascular Bundle: Phloem, Vascular Cambium*, Xylem *Vascular Cam: growth of new vascular tissue

15. Root Structure

16. D. Transportation System  Stem- Transport of water, food, and minerals  Support of plant  Storage of materials

17. Structures of the Stem  Epidermis (bark or green)=protection  Cork cambium =new growth of bark/ epidermis  Cortex = thick layer, sometimes contains chloroplasts, mostly for support  Vascular Bundle = contain transport tissues towards the middle of the stem  Xylem = transports water and minerals (generally in the middle)

18. More Structures  Phloem = transports sugars to all cells, located outside the xylem  Vascular cambium = separates the X and P, contains new cells for vascular growth  Pith = central portion of stem of tree, for storage

20. E. Reproduce Without Water  Spores/Cones/Seed-protective coat which prevents a developing embryo from drying out  Advent of pollen and seeds make it possible to reproduce far away from water  Pollen = plant sperm, light weight and won’t dry out, carried via wind, water, animal, etc

21. Pollen Images via SEM