9/20/ Evolution of Plants Ch 29-30

2 9/20/2015 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 9/20/2015 Evolution of Plants – p 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 9/20/2015 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

5 9/20/2015

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 9/20/2015 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 cone bearing = conifers, includes cycads and ginkgo increased vascular tissue, ex. evergreens, spruce, pine 4) Angiosperms - flowering plants, p , life cycle p.629

8 9/20/2015

9

10 9/20/2015 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

11 9/20/2015

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

13 9/20/2015 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

Plant Tissues Dermal – protective cover (water loss and disease) Ground – metabolic functions Vascular – transports materials between root and shoots systems 14 9/20/2015

15 9/20/2015 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 9/20/2015 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 9/20/2015 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 9/20/2015 Shoot system = Stems and Leaves Stem – attachment of leaves, similar structure to roots Leaves – photosynthetic organ

19 9/20/2015 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 9/20/2015 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 Primary Growth

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 21 9/20/2015

22 9/20/2015

23 9/20/2015 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 CO 2 and O 2  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

24 9/20/2015

25 9/20/2015

26 Transport of water & sugar Ch 36

27 9/20/2015 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 9/20/ mechanisms 1) Osmosis moves into roots, then into xylem high mineral gradient inside = root (turgor) pressure chemiosmosis, proton pumps

29 9/20/2015

30 9/20/2015 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

31 9/20/2015

32 9/20/2015 Control of the Stomata regulates amount of CO 2, O 2 and H 2 O aids in control of photosynthesis the guard cells control opening of stomata light, CO 2 depletion in leaves, high temps, and circadian rhythms regulate opening

33 9/20/2015

34 9/20/2015 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

9/20/ Nutrition Ch 37

36 9/20/2015 soil, water, nitrogen, minerals

Rhizobacteria, p /20/2015

Mycorrhizae, p /20/2015

39 Life cycle of plants Ch 38

40 9/20/2015 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 9/20/2015 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

42 9/20/2015

43 9/20/2015

Double Fertilization 44 9/20/2015

45 9/20/2015

46 9/20/2015

47 Plant controls Ch 39

48 9/20/2015 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

49 9/20/2015

50 9/20/2015 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 Plant stimuli = tropisms

51 9/20/2015 Photoperiodism response to a change in the photoperiod or length of daylight this is circadian rhythm of a plant (internal clock) controlled and reset by proteins called phytochromes night light is responsible for resetting the internal clock

52 9/20/ types of plants based on light – p839 1) long day plants – (short night) flower in the spring when night is shorter than a critical night period 2) short day plants – (long night) flower in late summer, early fall, when night exceeds a critical dark periodcritical 3) day neutral – plants don’t respond to daylight changes, flowering triggered by temp. or water amount

53 9/20/2015