Transcript Chapter 19: Kingdom Plantae

Chapter 19: Kingdom
Plantae
19.1 Land plants evolved
from green algae

Multicellular

Usually photosynthetic

Mostly terrestrial

Plant: multicellular autotroph, embryo
develops in female parent
Origins of Plants from
Algae

Closest ancestors = multicellular green
algae
– Charophytes

Some shallows dried out – plants
adapted
Challenges of Life on
Land

4 challenges
– 1. obtaining resources
– 2. staying upright
– 3. maintaining moisture
– 4. reproducing
1. Resources

Air – light, carbon dioxide
(photosynthesis)
– Shoots, leaves

Soil – water, mineral nutrients
– Roots

Vascular tissue
– System of tube-shaped cells that branches
throughout the plant
– Materials – roots/shoots
2. Staying Upright
Water - buoyancy
 Air – rigid support tissue

– Lignin – hardens plants’ cell walls
3. Moisture
Internal watery environment for cell
processes
 Adaptations:

– Waxy cuticle – retain water, slow exchange
gases between air and leaves
– Stomata – pores in leaf’s surface
 Gas
exchange
 Guard cells
4. Reproduction

Gametes / offspring – moist
– Sperm – pollen grain
– Egg – female tissues

Dispersal
– Sperm – wind / animals

Embryo develops in female parents 
seeds
Overview of Plant
Diversity

4 major periods plant evolution
– 1. Bryophytes – mosses
 No
seeds, no lignin
– 2. Pteridophytes – ferns
 Lignin
– vascular tissue
– 3. Gymnosperms – naked seeds, conifers
– 4. Angiosperms – flowering plants
Fig. 19-5
Figure 19-5
Fossil evidence indicates that
bryophytes are the oldest and
angiosperms the youngest of
the four major plant groups.
Alternation of
Generations
Diploid (Sporophyte) / haploid
(Gametophyte)
 Multicellular
 Fig. 19-6


Figure 19-6
A plant's life cycle
alternates between the
gametophyte and
sporophyte generations
Spores vs. Gametes
Spore
Gamete
New organism
without another cell
2 gametes fuse to
form a zygote
Tough coat – harsh
environments
Not adapted for
harsh conditions
19.2 Mosses and
Bryophytes
Damp habitats
 Lack rigid support tissues  grow
close to ground

Bryophyte Adaptations
Dominant generation = gametophyte
(1n)
 Nonvascular – no lignin
 Fig. 19-7 – overhead


Separate male/female gametophytes
– Flagellated sperm swim to eggs
– Fertilization – zygote grows from female
gametophyte into sporophyte
– Sporophyte (2n) = stalklike, capsule at
top
– Capsule produces/releases spores 
new gametophytes
Diversity of Bryophytes

Hornworts – hornlike sporophytes

Mosses
– Moss mat = many gametophytes in tight
pack
– Stalks = sporophytes
– Spongy – absorb / retain water

Liverworts – liver-shaped
gametophytes
19.3 Pteridophytes: Ferns /
other seedless vascular plants
Pteridophyte adaptations:
 Fig. 19-10 - overhead

– Vascular tissue – lignin – water, sugar
– Carboniferous period – fossil fuel
– Dominant generation = sporophyte
– Underside of fronds – spore capsules
 Haploid
spores, gametophytes
– Underside of gametophyte
 Produce
sperm / egg
 Sperm swim to egg  zygote  new
sporophyte
Diversity of
Pteridophytes
Ferns – most diverse
 Leaves = fronds
 Shady forests


Club “mosses” – little pine tree
– Vascular tissue, no seeds, forest floors
Horsetails
Marshy, sandy areas
 Outer layer = silica – gritty
 Scrub pots/pans
 “scouring rushes”

19.4 Pollen and Seeds
Evolved in Gymnosperms
Gymnosperm adaptations
 Gymnosperms = plants that bear
seeds that are “naked”

– Not enclosed in an ovary
– Most common - conifers
3 more adaptations than ferns:

1. Smaller gametophyte
– Dominant generation = diploid sporophyte = pine
tree
– Tiny gametophytes are in cones- protection

2. Pollen
– Reduced male gametophyte
– Contain cells that become sperm
– Wind – pollen from male to female- no water
needed

3. Seeds
– Plant embryo with a food supply in a protective
coat
Life Cycle of Gymnosperms
Male pollen cone - spore sacs with
haploid spores become pollen grains
(male gametophyte)
 Female gametophytes develop within
ovules

– On scale of cone – 2 ovules
– Large spore cell – meiosis
– 4 haploid cells – 1 survives female
gametophyte
Wind – blows pollen between trees
 Pollen lands in female cone
 Sperm matures and fertilizes egg in
female gametophyte
 2 eggs fertilized often – still only 1
zygote into embryo (seed) = new
sporophyte

Diversity of Gymnosperms
4 phyla today
 Gingkos

– Gingko biloba
 Fan-like
leaves
 Shed in autumn
 Cities– Tolerates
– pollution

Gnetophytes
– Mormon tea, desert shrub

Cycads – large, palm-like leaves
– Not true palms which are flowering plants

Conifers
– Spruce, pine, fir, junipers, cedar, redwood
– evergreen
19.5/20.1 Flowers and
fruits evolved in
angiosperms

Angiosperm Adaptations
– Gametophytes develop in flowers of
sporophyte
– Flower = specialized type of plant shoot
that functions in reproduction, only in
angiosperms
animal pollinators – variety
 Insects transfer pollen between flowers
 Grasses – wind pollinated – small flowers
 Attract
Flower Anatomy
Flower – specialized shoot
 4 rings modified leaves

– Sepals – protect flower bud
– Petals – color – insects
– Stamens – male, many
– Carpels (pistils) – female,1+
Stamen – produces
male gametophytes
Filament + anther
 Filament – supports anther
 Anther – pollen

– meiosis – spores – pollen grains = male
haploid gametophytes
Each pollen grain – 2 cells with thick
protective wall
 Fig 20-2 in packet

Carpels – female
gametophytes

stigma – style – ovary
– Stigma – sticky – pollen
– Style – supports stigma – pollen tube
– Ovary - ovules
Angiosperm Life Cycle
Pollen on stigma - pollination
 Pollen tube to ovule in ovary - style

– 2 sperm cells in pollen grain in tube
– In ovules – diploid cell –
 meiosis
haploid spores – ¾ die
 survivor enlarges – 3 cycles mitosis 
embryo sac – 7 cells (1 egg cell + 1 large cell
with 2 haploid nuclei)
4
Water lilies
Star Anise
– 1st sperm fertilizes 1 egg = zygote 
embryo
– 2nd sperm fuses with nucleus in larger
center cell  triploid cell = endosperm
(nutrient storage)
– “double fertilization” – zygote and
endosperm develop into seed
Many ovules, many seeds
 Seeds develop, ovary wall thickens
fruit
 Fruit = ripened ovary of a flower

– Protects, disperses seeds
– Colorful, attract animals, eat, digest,
waste

Monocots – day lilies, orchids, irises,
palms, grasses
– Flower petals – multiples of 3

Dicots – poppies, roses, peas,
sunflowers, oaks, maples
– Flower petals – multiples of 4 or 5
Human Dependence on
Angiosperms

Food – human, domestic animals
– Corn, rice, wheat, fruit, vegetables
Furniture, medicines, perfumes,
decorations, clothing fibers
 Threat – tropical rain forest

20.1 Reproductive
Adaptations contribute to
angiosperm success
Seed Development and
Dispersal

Seed parts
– Seed coat – outer layer – protects
embryo and endosperm
– Mini root and shoot
– Cotyledon – food storage
 Monocot,
dicot
Seed Dispersal

Animals
– fur – burr
– Eat, digest fruit, waste
Water – coconut
 Wind - dandelion

Seed Germination
Plant embryo grows in favorable
conditions
 Soak up water
 Expands
 Seed coat splits

Adaptations to
Germination
Dicot – hooked shoot tip
 Monocot – sheath around shoot tip
 Light – 1st leaves – photosynthesis =
seedling

Environment needed
for Germination
Usually just warm, moist
 Others

– Heavy rainfall – soil
– Long cold
– Intense heat - clearing
Challenges to sexual
reproduction
Pollination
 Damaged seeds
 Bad environment for germination
 Delicate seedlings – eaten, water

Asexual Reproduction
in Plants
Vegetative Propagation – offspring
identical to parent
 Cacti- drop stems
 Strawberries - runners

Lifespan
Annuals – one growing season
 Biennials – 2 years
 Perennials – multiple years

20.2 Plant Tissues /
Organs

Roots
– Anchor, support, absorb water, minerals
 Monocots
–
– fibrous roots: many thin roots
– grass
 Dicots
–
– Taproot: 1 large vertical root with small root hairs
– carrots, turnips, beets
Angiosperm shoots –
stem, leaves, flower

Stems
– Support leaves, flowers
– Nodes – where leaves are attached
– Internodes – between nodes
– Transport – vascular tissue – leaves and
roots

Buds
– Underdeveloped shoots
– Terminal bud – tip of stem
– Axillary buds – found in angles of leaf
and main stem – branches

Leaves
– Photosynthesis – food
– Blade – main leaf part
– Petiole – connects leaf to stem
– Veins – carry water, nutrients
– Modified leaves
– no petiole
 Celery – large petiole – eat
 Cactus spines
 Grass
Main Tissue Systems: Dermal,
Vascular, Ground

Vascular – transport roots / shoots
– Support
– 2 types:
 Xylem:
water, dissolved minerals up from
roots to shoots
 Phloem: food from leaves to roots, non foodmaking leaves, fruits
 Locations:
– Roots – center
– Stems – vascular bundles
• Monocot – scattered
• Dicot - ring

Dermal – outer covering
– Epidermis – protects young plant parts

Ground – makes most young,
nonwoody plants
– Photosynthesis, storage, support
– Root - cortex
Plant Cells: Parenchyma,
Collenchyma, Sclerenchyma

Parenchyma
– Food storage, photosynthesis, cellular
respiration
– Fruits, phloem

Collenchyma
– In strands, Celery strings
– young parts

Sclerenchyma
– Lignin-rich cell walls - ‘skeleton’ for mature plant
– xylem
20.3 Primary Growth

Meristematic tissue
– Meristems – create new tissue - always
 Mitosis,
cell then differentiate
– Apical meristems
 Tip
of roots, bud of shoots
 Lengthen, branch
– Primary growth
 Growth
in plant length
Primary growth in Roots


Root cap = root tip – protects dividing cells
of apical meristem
Root apical meristem
– 1. Replaces root cap cells
– 2. Produces cells for primary growth

Primary growth cells – 3 concentric circles
– Out – dermal
– Middle – bulk root tip – root’s cortex (ground)
– In – vascular tissue

Primary growth depends on
– Addition of new cells
– Cells elongating – more water
– Elongation – forces root tip through soil
Primary growth of shoots
Apical meristem – tip terminal bud
 Elongation – just below meristem –
push cells upward
 Some cells left behind

– Become axillary buds - branches

3 concentric circles – dermal, ground,
vascular
20.4 Secondary Growth
Woody plants – vines, shrubs, trees
 Growth in plant width
 Cell division in 2 meristematic tissues:
vascular cambium and cork cambium

Vascular Cambium
Between xylem and phloem
 Adds cells both sides

– Secondary xylem inside
– Secondary phloem outside
Added to primary tissues during
primary growth
 Secondary xylem becomes wood each
year during growing season

– Dormant in winter
– Stem / root thickens with each new xylem
Cork cambium  cork
 Cork cells die – thick, waxy walls left –
water loss, helps protect internal
tissues


Bark = everything outside vascular
cambium
= Phloem, cork cambium, cork
The Rings
Age from annual growth rings
 Result of vascular cambium activity
each year

Environment
 Each ring

– Spring wood – large, thin-walled
 Cool
temps, lots water
– Summer wood – narrow, thick-walled
 Hot,
dry
21.2 Vascular Tissue
Roots – absorb water, minerals
 Roots hairs –epidermal cells

– Grow between soil particles
– Surface area

Root pressure
– Pushes water up xylem – night
– Root epidermal and ground tissue cells
use ATP to get minerals – into xylem
– Endodermis – around vascular tissue,
waxy cell walls – doesn’t let water back
out
– Water enters (osmosis) – pushes xylem
sap upward
The Upward Movement
of Xylem Sap

Transpiration – loss of water through
leaves due to evaporation
– “transpiration pull”
Cohesion – same kind molecules stick
together (water)
 Adhesion – attraction between unlike
molecules (water sticks to cellulose in
xylem walls)

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Regulating water loss
Transpiration – lots water loss
 Evaporative cooling – keep good temp.
 More transpiration than water delivery
= wilting

Adaptations for water
loss

Leaf stomata – open / close – guard
cells

Day
– Stoma open
– Carbon dioxide in
– Sunlight and low carbon dioxide – more
potassium – water follows
– Guard cells swell and open

Night
– Stomata close
– Potassium ions leave with water
– Sag together
Flow of Phloem Sap
Phloem
 Move sugar from source to sink
(storage or use)
 Different sinks, different seasons

– Summer – taproots, tubers – storage
– Next Spring – become sugar source
Pressure – Flow
Mechanism
Sugar produced
 Active transport to phloem tube
 Up sugar conc. at source end of
phloem – water follows = up water
pressure at source
 pressure low at sink
 Sink end = sugars leave phloem, water
follows, pressure drops
 = water flows high to low

21.3 Carnivorous Plants
Some plants – N from animals
 Ex: sundews, Venus's flytraps, pitcher
plants
 Little organic N where they live
(wetlands, cold, acidic water, decay
slow)
 Still photosynthesize

22.1 Plant Hormones
Plant hormones – chemical
messengers (only takes a little)
 Control:

– Germination
– Growth
– Flowering
– Fruit production
Functions of 5 Major
Hormones:

Balance of hormones acting together
Auxins
Apical meristems – shoot tips
 Cell elongation

Auxin builds – shaded side
 Shaded cells lengthen more, more
water
 Uneven sides = bending

Secondary growth – vascular cambium
 Seeds – auxin – signal ovary to fruit
 Auxins - no pollination  seedless
fruit

Cytokinins
Cell division – made in roots
 Cytokinin with auxin

– Fewer / shorter branches near tip
Gibberellins

Fruit – seedless, larger
Abscisic Acid (ABA)
Limits cell division
 Stops growth
 Dormancy
 “stress hormone”

Ethylene
Fruit ripening
 “leaf drop”

22.2 Plant Responses

Rapid plant movements
– Touch
– Rapidly reversible

Tropisms – slowly grow toward or
away from a stimulus
– Slow to reverse
Thigmotropism
Touch
 Climbing plants – tendrils
 Seedling - obstacle

Phototropism
Light
 Uneven auxins – light one side

Gravitropism
Gravity
 Mature plant
 Seedling root / shoot

Stressful Environments

Drought
– Water loss, wilting, drop photosynthesis
– Succulents – water fleshy stems

Flooding
– Clogs air spaces, less cellular respiration
– Mangrove trees

Salt stress
– Root cells drop water – osmosis
– Halophytes – salt glands, pump out salt
Disease
Viruses, bacteria, fungi
 Adaptations

– Epidermis
– Chemicals – lignin
– Resistant genes
– Thorns, poisons