1. Ch 22-Intro. To Plants
BIG IDEA: What are the 5 main groups of plants & how have 4 of these groups adapted to life on land?

2. 22.1 What is a Plant?
Kingdom- Plantae- Eukaryotes w/ cell walls containing cellulose that perform photosynthesis
Need sunlight, gas exchange, water, and minerals to survive
Leaves allow for max. sunlight absorption

3. Plants need Oxygen(O2) for cellular respiration and Carbon dioxide (CO2) for photosynthesis. They release O2
Evolved structures to
prevent water loss and
absorb water

4. Plants can be unicellular (like green algae) or multicellular (like a tree or shrub)
Adapting to Life on Land
Fossils tell us that ancestors of modern plants lived in water.
Lacked leaves and roots, very small
Over time evolution of plants onto land required adaptations to prevent water loss, make them better at storing water, and capable of reproducing without water.

5. Land plants created new ecosystems, allowing new species to evolve
5 major groups based on 4 features:
Embryo formation
Water-conducting (vascular) tissues
Seeds
Flowers

6. Plant Life Cycle
Land plants alternate between a diploid (2n) and haploid (1n) phase- alternation of generations
2n-diploid phase: multicellular sporophyte, or spore-producing
1n-haploid phase: multicellular gametophyte, or gamete producing

8. Starts w/ sporophyte, which produces haploid spores through meiosis 
2. grow into gametophytes 
3. produce gametes (egg + sperm), which come together (fertilization) 
4. produces diploid zygote, develops into sporophyte

9. 22.2 Seedless Plants
Green algae were the 1st plants. Evidence of their existence ~550 million years ago.
- Characteristics: mostly aquatic in fresh and salt water, and some moist areas on land

10. Most green algae are unicellular w/ branching filaments
Lack specialized tissues for water transport b/c it’s readily available in environment
Life cycle can switch between 2n and 1n, but stay in whatever generation is suitable to their living conditions
-Ex: Clamydomonas

11. Multicellular green algae:
Some form colonies
Examples: Volvox and Spirogyra

12. Mosses are classified as bryophytes.
- Mosses have thin waxy coat to prevent water loss + root-like filaments- “Rhizoids”
- Some of the 1st land plants
- Lack vascular tissue (specialized structures to carry water)

13. Bryophytes have alternation of generations
-Gametophyte is dominant generation
-Depend on water for reproduction (to carry gametes)

14. Female reproductive structure: archegonia
Male reproductive structure: antheridia
-Sperm+egg= zygote in fertilization

15. Vascular tissue=tracheophytes
~420 million years ago vascular tissue developed
-Allows for transport or water/nutrients+ grow tall
Xylem transports water
Phloem transports nutrients

16. Vascular tissue is in many non-seed bearing plants, and all seed-bearing plants
Seedless (ex): fern.
- Root structure: rhizomes
Leaf- structure: fronds
Abundant in wet habitats, don’t require much lighta

17. Fern life cycle:
Dominant phase: 2n sporophyte
-Fertilization requires water

18. 22.3 Seed Plants
Seed is a plant embryo and food supply in a protective covering
How’d plants adapt to reproduce w/out water?
- Reproductive process in cones or flowers, transfer of sperm by pollen, and embryo protection in seeds

19. Types of seed plants= gymnosperms (cone bearing) and angiosperms (flower bearing)
Male gametophyte is in structure called pollen grain
Carried by wind or animals to female
Pollen + female reproductive structure= pollination

20. After fertilization zygote grows into sporophyte embryo.
Seeds can survive extremes like cold, heat, and drought b/c of protective seed coat
Grows into plants once conditions are right

21. Gymnosperm= “naked seed”, seeds are exposed on scales w/in cones.
Male
Female
Gymnosperm= “naked seed”, seeds are exposed on scales w/in cones.
Seed cones are larger than pollen cones.
In gymnosperms, the direct transfer of pollen to the female cone allows fertilization to take place w/out water

22. 22.4 Flowering Plants Flowering plants= angiosperms
Ovaries surround and protect the seeds
Angiosperms reproduce sexually by means of flowers. After fertilization, ovaries develop into fruits, that surround, protect, and help disperse seeds

23. Flowers provide an evolutionary advantage b/c they attract pollinators
Flowers provide an evolutionary advantage b/c they attract pollinators. Pollination is more efficient than relying on wind
Fruits provide an evolutionary advantage b/c they allow for seed dispersal
Soooo… angiosperms are the most complex and evolved of the plants

24. Flowering plants are classified according to the # of seed leaves (cotyledons) in their embryos.
Monocots produce 1 seed leaf.
Dicots produce 2 seed leaves

25. Woody plants are made of cells w/ thick cell walls for support.
Include trees, shrubs, and vines
Herabceous plants are smooth and nonwoody. Don’t produce wood.
- Include sunflowers, dandelions, and petunias