Transcript Evolution of Plants Ch 29-30 11/6/2015 Plants      multicellular, photosynthetic autotroph and eukaryotic cell walls made of cellulose, starch is storage Land based take up water via capillary action from.

Evolution of Plants
Ch 29-30
11/6/2015
1
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
11/6/2015
2
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
11/6/2015
water loss
3

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
11/6/2015
4
11/6/2015
5
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
11/6/2015
6
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
11/6/2015
7
11/6/2015
8
11/6/2015
9
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

11/6/2015
10
11/6/2015
11
Plant Structure and
Growth- structure and
function
Ch 35-39
11/6/2015
12
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
11/6/2015
13
Plant Tissues
Dermal – protective
cover (water loss and
disease)
 Ground – metabolic
functions
 Vascular – transports
materials between
root and shoots
systems

11/6/2015
14
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)

11/6/2015
15
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
11/6/2015
16
Root system



Roots = anchor, absorb, storage
taproot – 1 large root, strong and
large, ex. carrot
fibrous root – has extensions called
root hairs, increases SA
11/6/2015
17
Shoot system
= Stems and Leaves
 Stem – attachment of
leaves, similar structure
to roots
 Leaves – photosynthetic
organ
11/6/2015
18
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
– complete entire life cycle in 1 year or less
 Biennial – need 2 growing seasons to complete life cycle
 Perennial – live many years
 Annual
11/6/2015
19
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
11/6/2015
20
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
11/6/2015
21
11/6/2015
22
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
11/6/2015
23
11/6/2015
24
11/6/2015
25
Transport of water &
sugar
Ch 36
11/6/2015
26
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
11/6/2015
27
3 mechanisms
1) Osmosis
 moves into roots, then into xylem
 high mineral gradient inside
= root (turgor) pressure
 chemiosmosis, proton pumps
11/6/2015
28
11/6/2015
29
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
11/6/2015
30
11/6/2015
31
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

11/6/2015
32
11/6/2015
33
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
11/6/2015
34
Nutrition
Ch 37
11/6/2015
35

soil, water, nitrogen, minerals
11/6/2015
36
Rhizobacteria, p.793
11/6/2015
37
Mycorrhizae, p.767
11/6/2015
38
Life cycle of plants
Ch 38
11/6/2015
39
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
11/6/2015
40
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
11/6/2015
41
11/6/2015
42
11/6/2015
43
Double
Fertilization
11/6/2015
44
11/6/2015
45
11/6/2015
46
Plant controls
Ch 39
11/6/2015
47
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
11/6/2015
48
11/6/2015
49
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
11/6/2015
50
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
11/6/2015
51
3 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 period
3) day neutral – plants don’t respond to daylight
changes, flowering triggered by temp. or water
amount
11/6/2015
52
11/6/2015
53