Transcript PLANTS - Weebly

PLANTS
(pgs. 551-572)
KINGDOM PLANTAE
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Multicellular
Eukaryotic
Cell walls of cellulose
Carry out photosynthesis using
chlorophyll
Trees, shrubs, grasses, mosses, ferns
Most are autotrophs
Some are parasites or saprobes that live
on decaying material
What do plants need to survive?
-sunlight
-water
-minerals
-gas exchange (need oxygen and
carbon dioxide)
Early Plants
• The first plants evolved
from an organism much
like the multicellular green
algae living today. These
organisms in water
provided oxygen in the
atmosphere.
• The first land plants to
evolve were the mosses,
then the ferns, then the
cone-bearing plants and
finally the flowering plants.
Plants had to overcome 3 obstacles
to be terrestrial
Desiccation- prevent losing water. This is
accomplished by the waxy covering over the plant
called the cuticle.
Transport- in water, material could diffuse across
the membrane; on land this doesn't work. Vascular
tissues (xylem and phloem) run the length of the
plant and transport necessary nutrients.
Reproduction- in water the sperm could swim to the
egg, on land this is not possible. Now their sperm
(pollen) is air born.
PLANTS
• Botanists study plants
• Plants are divided into 4 groups
based on three features:
1. water-conducting tissues
2. Seeds
3. flowers
• 90% of plants on earth are
flowering plants
BRYOPHYTES
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Nonvascular plants called mosses,
liverworts, hornworts
Do not have true roots, stems or
leaves
Depend on water for reproduction
Small and must live in wet places
Examples: Sphagnum and peat moss
Phyla:
1. Phylum Bryophyta-mosses
that grow in extreme environments in
areas with water. They produce a thin
stalk, each containing a capsule called
the sporophyte. They have rhizoids
instead of roots.
2. Phylum Hepaticophytaliverworts. They resemble the shape
of a liver. they have flat leaves and
produce gametes in sporophytes that
look like little green umbrellas.
3. Phylum Anthocerophytahornworts. Produce gametes in
sporophytes that look like a green
horn.
Page 557....Draw and Label the
picture of Moss Sporophyte
Mosses, Liverwort, Hornwort
Seedless Vascular Plants
(tracheophytes)
• Vascular tissue is
specialized to conduct water
and nutrients throughout the
plant
• They are key cells in xylem,
a transport subsystem that
carries water upward from
the roots.
• Vascular plants also have
phloem, which transports
solutions of nutrients and
products of photosynthesis.
Seedless Plants
• Seedless vascular plants
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include club mosses, horsetails,
and ferns.
They have true roots, stems and
leaves
Roots are underground organs that
absorb water and nutrients or
minerals
Leaves are photosynthetic organs
that contain bundles of vascular
tissue that is gathered into veins
made of xylem and phloem
Stems are supporting structures that
connect roots and leaves and
transport water and nutrients between
them
Ferns have underground stems called
rhizomes and large leaves called
fronds
CLUB MOSSES
HORSETAILS
SEED PLANTS
• Seed plants became
the most dominant
group of
photosynthetic
organisms on land
Two groups:
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Gymnosperms
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Angiosperms
Gymnosperms
• Gymnosperms bear their
seeds directly on the
surfaces of cones.
• Conifers
• Page 565....draw seed
structure and label it
ANGIOSPERMS
• Angiosperms, also known as
flowering plants, bear their seeds
within a layer of tissue that
protects the seed.
• They develop unique
reproductive organs known as
flowers that attract pollinators.
• Flowers contain ovaries which
surround and protect the seeds.
• Angiosperm means "enclosed
seed".
• After pollination the ovary
develops into a fruit, which
protects the seed and aids in
dispersal when animals eat it.
Parts of a flower
Seeds
• A seed is an embryo of a
plant that is encased in a
protective covering called a
seed coat and surrounded
by a food supply.
• An embryo is an organism
in its early stage of
development.
Flowering Plants: Monocots vs. Dicots
Flowering plants can also be
subdivided into:
1. Woody Plants: made of
thick cell walls that support
the plant and include plants
such as trees, shrubs and
vines
2. Herbaceous Plants: that do
not produce wood as they
grow and include plants such
as dandelions, petunia, and
other flowers
Angiosperms can also be organized
based on plant life spans
• Annuals: grow only one
season
• 2. Biennials: grow for two
seasons
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• 3. Perennials: live for
more than two years
Chapter 23 – Special Tissue in Plants
• Roots: absorb water and nutrients,
anchors plants in the ground, hold
soil in place to prevent erosion
• Stems: are a support system for the
plant, a transport system carrying
nutrients, a defense system that
protects the plant against predators
and disease
• Leaves: are the plant's main
photosynthetic systems. The broad,
flat surfaces of many leaves
increase the amount of sunlight
plants absorb. Pores in the leaves
help prevent water loss and let
oxygen out and carbon dioxide in.
Main Plant Tissues
Plants consist of three main
tissue systems:
• Dermal
• Vascular
• Ground tissues
Dermal: The outer covering of a
plant. A single layer of
epidermal cells that are
covered in a thick waxy
coating called the cuticle. On
the underside of leaves,
dermal tissue contains guard
cells that regulate water loss
and gas exchange
Vascular Tissue
• Vascular forms a
transport system that
moves water and
nutrients.
• Xylem transport water
upward from the roots.
• Phloem transports
nutrients and products
of photosynthesis
throughout the plant.
Ground Tissue
• Cells that lie between dermal and vascular tissues
Meristems
• Clusters of tissues that make the plant grow
continuously throughout its lifetime.
• Apical meristem: located near the end, or tip, of each
growing stem and root. They let them increase in
length. It is the only plant tissue that produces new
cells by mitosis.
Roots
• The two main types of roots are:
– Taproots – which are found in dicots
• They are long and reach deep into the ground, or short like a
carrot that stores sugars and starches
– Fibrous – which are found in monocots
• Branch out to help prevent erosion
Roots
• A mature root has an outside layer,
the epidermis, and a central cylinder
of vascular tissue. Between these
two tissues lies a large area of ground
tissue.
• The surface of the root has cellular
projections called root hairs that
penetrate the spaces between soil
particles and produce large surface
area.
• Roots grow in length as their apical
meristem produces new cells near
the root tip. These fragile cells are
covered by a tough root cap that
protects the root as it forces its way
through the soil. It secretes a
slippery substance that lubricates it
as it grows.
• Water moves into the
vascular cylinder by osmosis
• The reason water and
minerals only move upward
through the system is
because it needs to generate
enough pressure to move
water out of the soil and up
into the body of the plant.
• Root pressure produced
within the cylinder by active
transport, forces water
through vascular cylinder and
into the xylem.
Stems
• Stems have three functions:
– They produce leaves, branches and flowers
– They hold leaves up to the sunlight
– They transport substances between roots and leaves
Vascular Tissues in Stems
• In monocots, vascular
bundles are scattered
throughout the stem.
• In dicots and most
gymnosperms, vascular
bundles are arranged
in a ring.
Primary Plant Body – Stem Anatomy
• Young dicot stems have
vascular bundles usually
arranged in a ringlike
pattern. The cells inside
the ring are known as
pith, while those
outside form the cortex
of the stem.
Primary and Secondary Growth
• Plants grow by producing new
cells at the tips of roots and
shoots. The method of growth
is called primary growth, and it
means the plant is growing in
length.
• The plant also grows in width.
This is called secondary growth.
In conifers and dicots,
secondary growth takes place in
lateral meristematic tissues
called the vascular cambium
(produces vascular tissues and
increases thickness of stems)
and cork cambium (produces
the outer covering of stems).
Bark
• Bark includes all of the tissue
outside the vascular cambium.
The cork cambium.
• The cork cambium surrounds
the cortex and produces a
thick protective layer of cork
which have thick walls made
of fats, oils, waxes and are
waterproof.
• The outermost cork cells are
usually dead. As the stem
increases in size, the dead
bark often cracks and flakes
off.
Leaves
• To collect sunlight,
most leaves have
thin, flattened
sections called
blades which are
attached to a stem
by a thin stalk
called a petiole.
Leaves
• They have pore like
openings on the
underside called stomata,
which allow for gas
exchange. Each stoma
consists of two guard cells
which control the
opening and closing of
the stomata by
responding to changes in
water pressure.
Transpiration
• Transpiration is the loss
of water through leaves.
The lost water is
replaced by water
drawn into the leaf
through xylem vessels
in the vascular tissue.
Transport in plants
• The combination of root pressure, capillary action
and transpiration provides enough force to move
water through the xylem tissue of even the tallest
plant.
• Water molecules are attracted to each other by
cohesion and to other substances by adhesion. The
movement of water upward against gravity because
of these two properties is called Capillary Action or
Transpiration Pull.
• For trees and other tall plants, the combination of
root pressure and capillary action does not provide
enough force to lift water to the top of the tree.
• The major force in water transport is provided by
the evaporation of water from leaves during
transpiration. When water is lost through this
process, osmotic pressure moves water out of the
vascular tissue of the leaf.
• The movement of water out of the leaf pulls water
through the vascular system all the way from the
roots. This is called transpiration pull. On a hot day,
a small tree may lose as much as 100 liters of water
to transpiration. The stomata and guard cells
control water loss.
Osmotic Pressure
• Osmotic pressure keeps a plant’s leaves and
stems ridgid, or stiff. High transpiration rates can
lead to writing from loss of water.
• Plants pump sugars into their fruits. This
movement takes place in the phloem. In cold
climaters, plants pump food down to the roots
for storage. Phloem carries out this seasonal
movement of sugars within a plant. Phloem is
able to move nutrients in either direction to meet
the nutritional needs of the plant.