Evolution of Plants

1. Evolution of Plants Ch 29-30

2. Plants • multicellular, photosynthetic autotroph and eukaryotic • cell walls made of cellulose, starch is storage • Land based • take up water via capillary action from the ground • have alternation of generation

3. Evolution of Plants – p.602-603 Major adaptations for land survival • 1) Except for Bryophytes (moss), dominant generation is the diploid sporophyte generation, so? • this masks mutations, greater survival • 2) Cuticle = waxy covering, p.604, so? • reduce water loss

4. 3) Vascular system → p.612 • reduced dependency on water (store it) so it can be farther away from it, tissue specialization • 4) Evolution of pollen & seeds (from spores)- • ability to move in the air (vs. water), p.620 • 5) In Anthophyta - gametophytes→ gametes enclosed & protected in an ovary, p.626 • 6) Conifers and Anthophyta have developed adaptations to seasonal variations in availability of water and light → ex. Deciduous trees

6. Divisions– (division is after kingdom, before phylum) 0) Charophytes (green algae) - precursor of plants, how know? • 4 reasons, p.600 • rosette-shaped cellulose-synthesizing complexes • peroxisome enzymes • structure of flagellated sperm • formation of phragmoplast 1) Bryophytes - simplest plants, no true stems or leaves, can't live far from water or grow tall • Repro. in water, antheridia (male) and archegonia (female) • gametophyte is dominant generation, p.607 • ex. moss, hornworts, liverworts, p.608

7. 2) Tracheophytes/Pteridophytes – seedless, vascular • xylem (water up) and phloem (sugar), p.614 • roots, hairs • sporophyte is dominant, makes spores, ex. ferns 3) Gymnosperms - "naked seed” or pollen replaced the spore, better dispersal, *p.622-623 • cone bearing = conifers, includes cycads and ginkgo • increased vascular tissue, ex. evergreens, spruce, pine 4) Angiosperms - flowering plants, p.630-631, life cycle p.629

10. Flower • petals, sepals attract pollinators • Stamen – male parts • Anther – produces pollen or microspores • Filament – holds the anther • Pistil – female parts (carpel(s)) • Stigma – sticky, capture pollen • Style – long tube, connects stigma and ovary • Ovary – where fertilization occurs, ovules are here, eggs are called megaspores, fruit here • ovary develops into a fruit, disperses seeds by insects, birds and mammals – coevolution • →plants use for medicines, wood and food

12. Plant Structure and Growth- structure and function Ch 35-39

13. Angiosperm - flowering plants 2 classes: • 1) Monocots- 1 cotyledon (storage seed), parallel veins, complex vascular bundle, floral parts in groups of 3's • 2) Dicots - 2 cotyledons, web-like veins, vascular tissue in a circle, taproots, floral parts in 4's or 5's

14. Plant Tissues Dermal – protective cover (water loss and disease) Ground – metabolic functions Vascular – transports materials between root and shoots systems

15. Types of plant cells- p744 • Protoplast – contents inside the cell wall 1) Parenchyma – unspecialized cells, most metabolic functions 2) Collenchyma- most growing cells, elongate stems, support 3) Sclerenchyma- don’t grow, very strong, some are dead, strengthened by lignin (p.612)

16. Types of plant cells (con’t)- p.745 Vascular system 4) Xylem - water & minerals up the plant, made of tubes called tracheids and vessel elements, dead at functional maturity 5) Phloem - food up and down to the plant, made of sieve tubes, alive, but reduced organelles to speed up transport

17. Root system • Roots = anchor, absorb, storage • taproot – 1 large root, strong and large, ex. carrot • fibrous root – has extensions called root hairs, increases SA

18. Shoot system = Stems and Leaves • Stem – attachment of leaves, similar structure to roots • Leaves – photosynthetic organ

19. Plant Growth = Germination • seeds remain dormant until a cue (ex. water, light or temp.)= photoperiod • 1st growth occurs when water is absorbed, seed coat cracks • Seeds – contain the embryo and storage material • the top of the embryo produces a shoot • Indeterminate Growth – grow throughout life, p.746 • Annual – complete entire life cycle in 1 year or less • Biennial – need 2 growing seasons to complete life cycle • Perennial – live many years

20. Primary Growth growth occurs at the tips of roots and shoots called apical meristem = meristematic tissue 3 zones of growth • zone of cell division - newly dividing cells • zone of elongation- new cell growth • zone of differentiation - cells differentiate

21. Secondary Growth Also lateral meristems = cylinders of dividing cells that increase the girth (width) of stems and roots Vascular cambium – adds vascular tissue called secondary xylem (wood) and secondary phloem Cork cambium – replaces the epidermis with thicker, tougher layer

23. Leaves • photosynthetic organ • made of blade (end), and petiole (connects the stem) 1) epidermis • Cuticle- waxy layer, holds in water 2) palisade mesophyll- many parenchyma cells and chloroplasts, photosynthesis 3) spongy mesophyll - space for CO2 and O2 • contains vein = xylem and phloem 4) Lower epidermis- bottom layer • Stomata- opening for gas exchange • Guard cells – surround stoma, control their opening • Modifications – see page 742, protection, water storage

26. Transport of water & sugar Ch 36

27. Water • absorbed in roots and passes up the xylem • also moves through the cell wall or plasmodesmata • Short distance flow, p.773 – regulated by Casparian strip

28. 3 mechanisms 1) Osmosis • moves into roots, then into xylem • high mineral gradient inside = root (turgor) pressure • chemiosmosis, proton pumps

30. 2) Capillary action – movement by adhesion • Adhesion – water "sticks" to sides of the tubes 3) Transpiration-Cohesion-Tension theory – most water moves this way, water potential • transpiration (bulk flow)– evaporation of water from the leaves, lower [water] in the leaves, so water goes up, works by negative pressure, p.774 • cohesion – attraction of water molecules

32. Control of the Stomata • regulates amount of CO2 , O2 and H2O • aids in control of photosynthesis • the guard cells control opening of stomata • light, CO2 depletion in leaves, high temps, and circadian rhythms regulate opening

34. Sugar, p.779 • Translocation = movement of sugar through the phloem • source/sink – sugar moves from the source of sugar (leaf) to the place where it is used = sink • pressure flow – high solute at source→ lowers water potential →water into sieve tubes→ causes lower pressure at sink →the pressure difference moves sugar through

35. Nutrition Ch 37

36. soil, water, nitrogen, minerals

37. Rhizobacteria, p.793

38. Mycorrhizae, p.767

39. Life cycle of plants Ch 38

40. Alternation of generation • Gametophyte – haploid(n) generation, produces haploid gametes by mitosis • gametes then combine to form a diploid plant • protected within the sporophyte plant • Sporophyte – diploid(2n) part, makes haploid spores by meiosis • →In bryophytes gametopyte is dominant • →In others, sporophyte is dominant

41. Cycle p.802 • 1) spores (n) develop from the sporophyte plant • 2) spores form gametophyte (n) part of plant • 3) gametophyte forms gametes(n) • 4) gametes combine (fertilization) to form zygote (2n) • mitosis, develop into mature sporophyte (2n), back to 1

44. Double Fertilization

47. Plant controls Ch 39

48. Plant Hormones • Auxin – made at apical meristem or embryo, elongation of stem, root growth, fruit growth • Gibberellins – made at meristems, growth in young parts, flowering, leaf growth, excess can cause bolting, germination • Cytokinins – stimulate cell division and differentiation, growth of lateral buds, slows leaf aging • Ethylene gas– ripening of fruit, stimulates flower growth • Abscisic acid – inhibits growth, closes stomata, aids dormancy

50. Plant stimuli = tropisms • 1)gravitrophism – response to gravity, p.841 • 2) thigmotrophism – response to touch, p.842 • 3)phototropism –response to light, auxin is made →plant grows, stem bends toward light because auxin collects on shady side