Section 22-1
INTRODUCING PLANTS
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Criteria for Kingdom Plantae
Cell type: Eukaryotes.
 Cell number: Multicellular.
 Cell structure: Cell wall made of cellulose.
 Mode of nutrition: Autotrophic.
 Carry out photosynthesis using the green
pigments chlorophyll a and b.

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Plant Life Cycle
All plants have
a life cycle with
alternation of
generations, in
which the
haploid
gametophyte
phase
alternates with
the diploid
sporophyte
phase.
Textbook,
page 552
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Plant Life Cycle
Alternation of Generations!

Haploid (N)
– Gametophyte plant (N)
– Produces either sperm or eggs.
 (gametes

= reproductive cells)
Diploid (2N)
– The sperm and egg join to create the
Sporophyte plant (2N), which is diploid.
– Egg and sperm join to create spores by
meiosis.
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Evolutionary Cladogram of Plants
(Angiosperms)
(Gymnosperms)
Seedless Vascular
(Bryophytes)
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Four Groups of Plants and examples:
Bryophytes – mosses
Seedless Vascular – ferns
Gymnosperms – cone-bearing
Angiosperms – flowering
Three Evolutionary developments among plants:
1. Vascular tissue
2. Seeds
3. Seeds enclosed in fruit
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Plant Survival




Sunlight needed to carry out photosynthesis.
Minerals and water are needed to make
new plant parts.
Gas exchange (through photosynthesis and
cellular respiration) must occur without
losing excessive amounts of water.
Movement of water and nutrients is
required for plant energy production and
growth.
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Overview of the Plant Kingdom
The majority of plant life is Flowering Plants
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Section 22-2
BRYOPHYTES
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Bryophytes (ex. mosses, liverworts, hornworts)
Life cycles depend on: water
for reproduction.
 Environment: in moist
environments (bogs, near
streams, in rain forests)
Sphagnum moss is used in
gardening (for moisture),
and when compacted
(peat) it’s used for fuel.

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(Angiosperms)
Typical
Moss
Plant
Capsule
Stalk
Sporophyte
Leaflike
Structure
Gametophyte
Stemlike
Structure
Rhizoid
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Section 22-3
FERNS:
Seedless Vascular Plants
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Ex. horsetails, club mosses,
ferns.
Evolutionary
Development:
Vascular Tissue
Vascular tissue: specialized tissue to transport
water and nutrients throughout the plant.
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Phylum Pterophyta



Leaves are called fronds.
Undergound stems called rhizomes .
Habitat: moist, shaded forest areas.
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Vascular Tissue
– Xylem (moves
water upward).
– Phloem (moves
nutrients and
carbohydrates
throughout
the plant).
– Tracheids are specialized cells that can move fluids
through the plant body, even against the force of
gravity.
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Typical Fern Plant
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
Sori – clusters of sporangia (spores on
the underside of fronds).
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Section 22-4
GYMNOSPERMS:
Seed Plants
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Gymnosperms: Cone Bearers



Means “naked seed”.
Examples: conifers
(pines & spruces) and
palms (cycads &
ginkgoes).
Second evolutionary
development of plants
= seeds.
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Reproduction
Germination: early growth stage of a
plant embryo.
 Dormancy: period of time during which a
plant embryo is alive but not growing.
 Features that allow seeds to reproduce
without water:

– Reproduction in cones.
– Movement of gametes by pollination.
– Protection of embryo in a seed.
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Diagram of a Pine Seed

– Growing part of
seed
Embryo
Endosperm
– Endosperm
– provides nutrition
for the developing
seed.

Seed Coat
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Embryo
Seed Coat
– Protective outer
covering of the
seed.
Pollination

Transfer of pollen from the male
reproductive structure to the female
reproductive structure.
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Adaptations
 Needles
 Winged
Seeds
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Section 22-5
ANGIOSPERMS:
Flowering Plants
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Anthophyta: Angiosperms



Dominate plant life.
Flowers are the reproductive
organs of plants.
Two functions:
– has ovaries (fruit) to
protect the seeds.
– Attracts animals which
help with pollination.
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Diversity of Angiosperms
Can be classified into:
1. Stems: herbaceous vs. woody.
2. Lifespans: annuals, biennials, perennials.
3. monocotyledon vs. dicotyledon.
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Monocots vs. Dicots
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Lifespans


Annuals
– Complete life cycle in one year.
Biennials
– Life cycle takes 2 years
Year one: germinate and grow roots, maybe leaves.
 Year two: grow new stems, leaves, and flowers.


Perennials
– Live through many years
May die back in winter, but re-grow in the spring
(asparagus, peonies, many grasses).
 Most have woody stems (palms, trees, honeysuckle).

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Plant Parts

Transport
– Roots, stems, leaves.

Energy Production
– Leaves.

Reproduction
– Flowers.
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Roots (Transport)

Taproot: primary root grows down from the
stem with secondary roots forming.
– ex. carrot, potato, radish

Fibrous: small lateral roots that spread out just
below surface of the soil.
– ex. weeds
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4 Root Functions
Absorbs water & nutrients from the soil.
 Transports water & nutrients to stem.
 Anchors plant to maintain stability.
 Stores food and
water.

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Structure of Roots
Outermost layer of cells
Site of absorption
Tissue that
stores starch
Within cortex;
contains cells
for transport of
water,
nutrients, &
minerals)
Protection of root tip
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Stems (Transport)

Woody
– Thick cell walls that
support the plant.
– Trees, shrubs, and vines.

Herbaceous
– Stems are smooth,
supported by hydrostatic
pressure (turgor).
– Dandilions, zinnias,
petunias.
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Function of sapwood: active xylem that
transports water and minerals
 Function of heartwood: old
nonfunctioning xylem that helps support
the tree
 Cork cambium produces: protective layer
of cork

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Stems
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3 Functions of Stems
Transports water & nutrients from roots
to leaves.
 Supports/produces leaves, branches,
fruits/flowers.
 Stores food.

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Transport in Plants

Capillary action
– the tendency of water
to rise up a thin tube.
– Contributes to the
movement of water up
cells of the xylem
tissue.
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Leaves (Transport &
Energy Production)

Photosynthesis
– Process that plants use to produce their food.
– 6CO2 + 6H2O C6H12O6 + 6O2

Transpiration
– Loss of water and exchange of carbon dioxide.
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Anatomy of a leaf
Letter Structure
Function
A
Cuticle
Thick waxy layer, protects against water loss
B
Epidermis
“Skin” of leaf – site of gas exchange
C
Vein (Xylem)
Pumps WATER up from soil through roots
D
Vein (Phloem)
Moves NUTRIENTS and CARBOHYDRATES
throughout the plant.
E
Mesophyll
Middle layers of leaf – site of
PHOTOSYNTHESIS
F
Stomata
Outside layer of leaf opening in epidermis –
site of GAS & WATER EXCHANGE
G
Guard Cells
Control Stomata – trigger when water is LOW
causing stomata pores to close.
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Leaves (Transport & Energy
Production)

Cuticle
– Waxy outer surface;
retains moisture.

Mesophyll
– Middle layer of leaf
where
photosynthesis
occurs.
– Palisade layer
(upper).
– Spongy layer
(underside).
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Structure of Leaves (cont’d)

Epidermis
– “Skin” of leaf responsible for gas
exchange.
– Upper and lower.

Stomata
– Outside layer of leaf
opening in epidermis
where gas and water
exchange (controlled
by guard cells).
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Gas Exchange in Leaves

Stomata
– Outside layer of leaf opening in epidermis where gas and
water exchange (controlled by guard cells).

Turgor pressure (water pressure)
– High Turgor pressure: Stomata open
– Low Turgor pressure: Stomata close
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Leaf Vein Types
Parallel
Pinnate
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Palmate
Structure of Flowers
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Typical Flower Structure

Petals
– Highly colored part
of the flower, may
contain perfume
and/or nectar
glands.

Sepals
– Small green
structures on the
base of a flower
that protect the
flower bud.
Image found at: http://biology.clc.uc.edu
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Male Plant Organ

Stamen contains:
– Anther: produces pollen.
– Filament: upholds anther.
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Female Plant Organ

Pistil (carpels) contains:
– Stigma: sticky for pollen to attach.
– Style: sperm travel to ovary.
– Ovary (fruit): stores ovules (eggs).
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Seed Dispersal



Wind
Water
Animal
Flower Pollination


Animals
Wind
Factors that affect seed germination:


Temperature
Moisture
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Plant Response
Plant hormones – chemical substances
that control a plant’s patterns of growth
& development.
 Target cell – cell that has a receptor for a
particular hormone.

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Tropisms (Response)

Tropism – response of a plant to an
environmental stimulus.
– Gravitotropism: response of a plant to the force of
gravity.
– Phototropism: tendency of a plant to grow towards
light.
– Thigmotropism: response of plants to touch.

Auxin – substance produced in the tip of
the seedling that stimulates cell elongation.
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Photoperiodism: the timing of seasonal
activities such as flowering and growth.
 Herbicides: auxinlike compounds in high
concentrations that are toxic to plants
therefore inhibiting growth.
 Chemical defenses: many plants defend
themselves against insect attack by
manufacturing compounds that have
powerful effects on animals, ex. poison
oak.

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