Transcript File

Chapter 8:
Introduction to
Plants
8-1: The Plant Kingdom
Members of the plant kingdom share
important characteristics:
• Eukaryotes
• Multicellular
• Autotrophs
• Perform Photosynthesis to make food.
Living on Land
Unlike something like multicellular algae,
plants do not have water surrounding them to
help them:
• Hold their bodies toward the light
• Obtain nutrients
• Reproduce
For a plant to survive on land they must:
1) Have a way to obtain water/materials
2) Retain water
3) Transport materials throughout their body
4) Support their body
5) Reproduce successfully
Obtaining Water and Materials
Plants must have adaptations that allow them
to obtain water and materials from the soil.
Retaining Water
Because there is more water in plant cells than
there is in the air, a plant must have an
adaptation to reduce water loss to the air.
Cuticle- waxy water-proof layer of a plant
Transporting Materials
Just like our bodies, plants need to transport
materials to its entire body.
In general: -water and minerals are absorbed
by the bottom of the plant and
need to move up.
-Food is made in the top of the
plant and need to move down.
Most plants have tissues that allow them to
perform this task.
Tissue- group of cells performing a task
Vascular Tissue- internal system of tubelike
structures that transport materials in a plant.
Plants with vascular tissue are called vascular
plants and can grow tall.
Support
Land plants do not have water to support them
toward the light.
The photosynthesizing parts of plants (leaves,
stems) need as much exposure to sunlight as
possible.
In vascular plants, the vascular system
strengthens and supports the plant to reach for
the light.
Reproduction
All plants reproduce sexually and it involves
fertilization.
Fertilization- when a sperm cell unites with an
egg cell.
Zygote- the fertilized egg
In water, the sperm cell can swim to the
egg. But land plants need an adaptation
to make it possible for fertilization to
occur.
Plants have a complex life cycle made up of
two different stages or generations.
Stage 1: the sporophyte produces spores that
eventually grow into new organisms.
Stage 2- the spore develops into the
gametophyte that produces two different
gametes- sperm cells and egg cells.
Plant
Life Cycle
Sporophyte
Meiosis
And Grow Up
Fertilization
Stage 1: Sporophyte
(DIPLOID)
Spores
Gametes (egg and sperm)
Stage 2: Gametophyte
(HAPLOID)
Grow up
Mitosis
Gametophyte
Types of Plants
Nonvascular
(Chapter 8)
Seedless
Vascular
(Chapter 8)
Seeded
Vascular:
category
Mosses and
Relatives
Ferns and
Relatives
Gymnosperms Angiosperms
types
mosses,
liverworts,
hornworts
ferns, club
mosses,
horsetails
Cycads,
ginkgo,
gnetopythes,
conifers
Monocots,
dicots
Vascular
Tissue?
No
Yes
Yes
Yes
Seeds?
No
No
Yes
Yes
Facts
Low-growing,
Live near
water, no
roots
Use spores to
reproduce,
true stem,
leaves, roots
Seeds used to
reproduce,
true stem,
leaves, roots
Seed
enclosed in
fruit, flowers
present
Non-flowering
(Chapter 9)
Seeded
Vascular:
Flowering
(Chapter 9)
8-2 Nonvascular Plants
General Characteristics of Nonvascular Plants:
• Low-growing
• Lack vascular tissue- system of tubelike
structures that transport water and other
materials throughout the plant.
• Passing of materials is just from cell to cell.
• Lack roots
• Obtain water directly from surroundings
• Sperm cells use the watery environment to
swim to the egg cells.
• Examples of nonvascular plants: mosses,
liverworts, hornworts
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Mosses
There are 10,000 species
of mosses.
Rootlike structure called
rhizoid.
sporophyte
The sporophyte grows
out of the gametophyte.
Sphagnum moss is found
in bogs that forms peat.
Peat is used as fuel, to
heat homes, and cook
gametophyte
food.
Many mosses are
pioneer plants.
Moss traps soil that can
eventually support other
plants.
capsule
stalk
Stemlike structure
leaflike structure
rhizoid
•
•
•
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•
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Liverworts and Hornworts
8,000 species of
liverworts.
Found growing as a thick
crust on moist rocks or
soil along streams.
Most liverworts grow flat
on the ground.
Fewer than 100 species of
hornworts.
Seldom found on rocks or
tree trunks.
Live in moist soil, often
mixed with grass plants.
8-2 Review
1)What are five general
characteristics of nonvascular
plants?
2)What are three examples of
nonvascular plants?
3)Draw and label the parts of a
moss plant.
4)Where do liverworts grow?
5)Where do hornworts grow?
8-3: Seedless Vascular Plants
General Characteristics of Seedless Vascular Plants:
• Vascular Tissue present
• Use spores to reproduce
• Examples: ferns, club mosses, and horsetails
Vascular Tissue:
Vascular Tissue allows plants to grow tall.
Vascular plants are better suited for life on land
because vascular tissue solves the problems of
support and transportation.
Transportation- food and water are transported
quickly through the vascular tissue.
Support- Vascular tissue strengthens the plants
body like a bundle of straws.
Spores for Reproduction:
Vascular plants still need to grow in moist
surroundings.
1) Plant releases spores into surroundings
2) They grow into gametophytes
3) Gametophyte produces egg and sperm cells
4) There must be enough water for fertilization to
occur.
Ferns
• First fern appeared on land
400 million years ago
• 12,000 species alive today
• Range in size from very tiny
to tall trees.
Fern Structure
• True stems, roots, and
leaves.
• Stems are underground
• Leaves grow upward from
stem
• Roots grow downward from
stem
• Roots anchor the fern to soil
to absorb water and
nutrients.
Stem
Fern Structure (cont.)
• The leaves are called fronds.
• Has a divided leaf structure.
• Cuticle helps the plant retain water.
• Fronds start off as a curled up
structure often called “fiddleheads.”
• As they mature they uncurl into
leaves (fronds).
Reproduction in Ferns:
• The full grown fern with fronds is the
sporophyte stage.
• Spores develop on the underside of
fronds.
• Spores are released and wind/water
carry them distances.
• If a spore lands in moist soil, it grows
into the gametophyte stage.
The Importance of Ferns
Ferns make nice houseplants because they are
attractive and easy to grow.
Ferns can help grow other kinds of plants.
Some ferns are good to eat especially when they are
fiddleheads.
In some farms, ferns are grown to provide a place for
bacteria to grow. That bacteria is used as a natural
fertilizer.
Seedless Vascular Plants: Club Mosses and
Horsetails
• Like ferns, club mosses and horsetails have
true roots, leaves and stems.
• They also have a similar life cycle.
• There are only a few species alive today.
• Do not be confused by their name: Club Mosses
are not mosses because they have vascular
tissue!
• They look like tiny pine trees that grow in moist
woodlands.
• Horsetails have stems that are jointed that have
long needlelike branches that grow out in a
circular pattern.
• The stem contain silica and that made them
good for scrubbing pots and pans during colonial
times.
Draw it!
A frond is a leaf of a fern. It is a
large leaf with a “divided leaf
structure” meaning several long,
thin leaves branch off of a central
stem-like structure. What does a
frond look like? DRAW IT!
Draw it!
A fern is a vascular plant. It has
vascular tissue that supports and
transports materials. Vascular
tissue is like a bundle of straws.
What would it look like if you cut a
fern stem in half and looked down
at it? DRAW IT!
Draw it!
A young fern frond is called a
fiddlehead. It is a curled up baby
frond that uncurls as the plant
matures. It kind of looks like a
new years eve horn that you blow
into. DRAW IT!
Draw it!
Spores develop in little containers
on the underside of the fronds.
They look like simple little brown
dots, but they actually contain
thousands of spores. What would a
frond look like from underneath?
DRAW IT!
8-4: Feeding the World
Farmers need to be able to grow enough food for
our growing world.
In laboratories scientists are developing plants that
are more resistant to insects, disease, and drought.
They are also developing plants that produce more
food per plant with new high-tech practices
involving genetic engineering.
Producing Better Plants
• Wheat, rice, and corn are the major sources of
food for people on earth today.
• One challenge for farmers is that these crops
only grow in certain climates.
• Another challenge is that plants only produce a
limited amount of food per plant.
• Genetic engineering of plants have helped to
solve these problems.
• Plants can grow in a wider range of climates, be
resistant to damage, and produce more food.
Improving the Efficiency of Farms
• New technology using satellites help farmers with
“precision farming”- knowing just how much
fertilizer and water each field requires.
• Precision farming saves farmers time and money,
and helps farmers maintain ideal conditions for
growing.
• Precision farming also benefits the environment
because farmers use only as much fertilizer as
the soil needs.
• Less fertilizer means less nutrients drain off into
lakes and rivers- thus reducing the chance of
algal blooms.
Hydroponics
• In some areas of the world, poor soil does not
support the growth of crops.
• In these areas, people can use hydroponics- a
method where plants are grown in nutrient-rich
solutions instead of soil.
• Unfortunately, hydroponics is expensive, but it
does help grow crops in some areas.