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Plants and Flowers
7th grade science
Part ONE
Plants
There are many strange plants throughout the world
Some plants trap animals, some bloom only once every thirty years,
and some have flowers that smell like rotting meat!
Venus Flytrap,
Dionaea
muscipula, is a
carnivorous
plant that
catches and
digests animal
prey—mostly
insects and
arachnids
Corpse Flower
smells like rotting meat when it blooms, only opens
up once in several years, and only stays in bloom for
a few days.
You interact with plants every day, when you eat, when you see
moss on a tree or plants in a pond. All plants, even the strange
ones have things in common.
What is a Plant? -Plants belong to the Kingdom plantea, they share
several characteristics. Nearly all plants are autotrophs, organisms
that produce their own food. All plants are eukaryotes that contain
many cells.
Plants are autotrophs, a sun powered food-making factory.
Sunlight provides the energy for this food making process,
photosynthesis. Plants are multicellular, with cells organized into
tissues. Plants vary in size from the tiniest moss to the largest
redwood tree.
Adaptations for Living on Land- Most plants live on
land but some live in water. Water plants obtain water
and nutrients directly from the water. Water also gives
them a place to grow and when these plants reproduce
the sperm cells swim through the water to the egg cells.
For plants to survive on land, they must
have several things…….
•a way to get water and nutrients from their
environment,
to retain or hold onto the water so
they don’t dry out,
a way to transport
materials in their
bodies,
a way to support their bodies giving them a
place to grow.
a way to reproduce
To live on land plants must have
adaptations to survive. They need a way to
get water and nutrients from the soil.
Retaining Water- One adaption that helps a
plant reduce water loss is a waxy layer called
a cuticle which covers the leaves of most
plants.
Transporting Materials.Plants need to transport materials
from one part of its body to
another. In small plants it is easy
for materials to move from one
cell to the next. Large plants need
a more effective system. These
plants have transport tissues
called vascular tissues. These
tissues are tube like structures
inside a plant that water, minerals
and food move.
Support- A plants food making parts must be exposed to as
much sun as possible. Rigid cell walls and vascular tissue
strengthen and support the bodies of these plants so they are best
exposed to the light.
Reproduction- All
plants go through
sexual reproduction
that involves
fertilization, the
joining of a sperm
cell with an egg
cell. A zygote is the
fertilized egg. For
some plants the
sperm cell swims
through the water.
Other plants have
adapted to their
environments and
use different
methods of
fertilization.
Classifying Plants part 2
Scientists
“informally”
group plants into
two major groups:
non-vascular and
vascular.
Nonvascular Plants - Nonvascular plants lack a
well-developed system of tubes for transporting
materials. (non = not, vascular = tubes to transport
fluids) Growing in damp shady places these plants
are low growing and don’t have roots. They absorb
what they need directly from their environment.
These materials pass through the cell walls into the
cells. This is a slow process compared to vascular
transport. The cell walls are thin and can not
support a tall plant, most of these plants are only a
few centimeters tall.
Vascular Plants
Plants with defined vascular tissues are
called vascular plants. Vascular plants
are able to transport materials over
greater distances efficiently and quickly.
The vascular tissues also provide support.
These plants can grow very tall.
Plant Origins- The oldest plant fossils are
about 400 million years old. These plants
already had many adaptations such as
vascular tissue. Through chemical analysis
of different plants, such as the specific
make up of chlorophyll, as well as genetic
testing, has lead scientists to hypothesize
that ancient green algae is the ancestor of
today’s modern plants. Some scientists
think that green algae should be classified
as a plant. Some plants, such as the Gingko
tree, and many others have been around
since prehistoric times.
Complex Life Cycles -Plants have complex
lifecycles that include two different stages, the
sporophyte stage and the gametophyte stage.
In the sporophyte stage
(SPOH ruh fite) stage, the
plant produces spores.
Spores are tiny cells that
grow into new organisms.
Spores develop into the
plants next stage, the
gametophyte stage.
In the Gametophyte stage
(guh MEE tuh fyt) the plant
produces sperm cells and
egg cells.
The sperm cell and egg cell then combine to form a zygote. The
zygote develops into sporophyte. The sporophyte produces spores
which develop into the gametophyte which produce sperm and egg
cells…..the sporophyte looks very different from the gametophyte.
Characteristics of Seed Plants
part 3
Parvis e glandibus quercus, a Latin proverb
translates to "mighty oaks from tiny acorns
grow."
What is a Seed Plant?- Seed plants outnumber
seedless plants by more than ten to one. We eat many
seed plants, rice, squash, tomatoes, peas, and squash
are all see plants. We even wear cloths made from
seed plants like cotton and flax. Many homes are made
from see plants, oak, pine, maple trees, and in some
country people “thatch” their roofs with thatch which
is a grass. We breathe oxygen that is produced mainly
by seed plants.
Seed plants
share two
very
important
characteristics
1. They have
vascular
tissue
1. They use
pollen and
seeds to
They also have roots, stems
(bodies), and leaves. Some
have complex life cycles
that include the sporophyte
and gametophyte stages.
The gametophytes are
microscopic, the plants are
the sporophytes.
The vascular tissue helps
support the plant as well as
transports nutrients. There
are two types of vascular
tissue. Phloem (FLOH um)
vascular tissue transports
food from the leaves to the
rest of the plant. Water and
minerals travel through
vascular tissue called
xylem, (ZY lum) from the
roots to the top of the plant
where the stems and leaves
are.
Pollen and Seeds- Seed plants can live in
many environments. They produce pollen, a
tiny structure that later becomes sperm cells.
Once the sperm cell fertilizes the egg, seeds
develop. A seed contains a young plant inside
a protective covering; the covering helps
young plants from drying out.
How Seeds Become New Plants- All seeds are
similar. Inside each seed is a partially developed
plant. If the seed lands in an environment with
favorable conditions it will begin to grow.
Seed Structure-A seed has three main
parts:
Embryo: stores the beginning of roots,
stems, and leaves. Uses the food stored
in the seed until it can make its own
food through photosynthesis.
The embryo has one or more seed leaves
called cotyledons (kaht uh LEED unz)
in some plants food is stored in the
cotyledons, in other is it stored outside
the embryo.
The outer covering is the seed coat. The
covering protects the seed like plastic
saran wrap protects food. It keeps
moisture in allowing the seed to remain
inactive for long periods of time until it
is in the perfect environment for
germination. In many plants fruit
Seed Dispersal.- The scattering of seeds is called dispersal.
Seeds are dispersed in many ways.
1. Other organisms eat the fruit
around the seeds and also
consume the seeds. The seed
travels through the digestive
system and are deposited in
new areas.
2. Some seeds have barb like
structures and “hitch hike” a
ride on an organism to a new
spot.
3. Some seeds travel in water,
across oceans (like coconuts)
4. Lightweight seeds can be
carried in the wind. Some of
these seeds have structures to
help them travel away from
the parent plant.
5. Some plants eject their seeds;
the force scatters the seeds in
many directions.
6. Being far away from the
parent plant so it does not
have to compete for light,
food and water helps to
increase the survival of the
new plant.
GerminationWhen the conditions are right a seed will
germinate. The seed absorbs water from the environment
allowing the embryo to absorb food and start to grow.
Germination (jur muh NAY shun) occurs when the embryo
begins to grow and pushes out of the seed. First the root
pushes downward. Next the stem and leaves push upward.
Once you see the leaves the plant is called a seedling.
Roots - There are 2 major root systems.
Fibrous root system is
made up of a tangled
dense mass of similarly
sized roots. When you
pull these plants, such as
grass, out of the ground
they bring a lot of soil up
with the root system.
A taproot system
has one thick main
root with smaller
roots branching out
from the main root.
This kind of root
system is difficult
to pull out of the
ground. Carrots
have a tap root.
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Root Structure- The root cap is a rounded tip at the
end of the root that protects the root from injuring
itself as it grows. Behind the root cap are cells that
divide quickly to form new root cells.
Root hairs
grow out of
the root and
enter the soil
to absorb
water and
nutrients and
to anchor the
plant in the
soil.
The absorbed material is transferred to the vascular
tissue (xylem) where it is transported up into the plant.
From the leaves the vascular tissue (phloem)
transports the food back to the root tissue to be stored
or fuel plant growth.
Stems- Stems
carry
substances
between stems
and leaves,
provide
support and
hold the leaves
up so they are
exposed to the
sun.
Stems can be
herbaceous
(hur Bay
shus) or
woody.
Herbaceous
stems are
often soft and
contain no
wood.
Woody stems are hard and rigid.
Woody stem has an outer layer of
protective bark surrounding a layer
of cambium (KAM bee um) which
divide to produce vascular tissues. At
the center of the wood is the heart, it
is darker and has become hard. It
does not transport fluids but it does
provide support. When you look at a
tree stump you can see the each ring,
one ring is created each year of the
trees life. Count the rings and you
can see how old the tree is.
Each
contains
both kinds
of vascular
tissue as
well as
other
supportive
cells.
Leaves- Leaves of all shapes and sizes
capture the suns energy and carry out
photosynthesis.
The top and bottom layer of the leaf
protect the inside of the leaf. The cells on
the inside are surrounded by vascular
tissues or veins. The surface of the leaf
has stoma. Stoma are pores that allow
substances into (CO2) and out of ( O2,
H20) the leaf. Stoma translated to mouth
but don’t look like a mouth.
Pea Leaf Stoma
The Leaf and Photosynthesis- The leaf is a
perfect structure for carrying out photosynthesis.
Chloroplasts are near the upper surface to collect
the most sunlight most efficiently.
Photosynthesis-Photosynthesis is the process of which plants
change sunlight into energy. This energy is their food which contains
oxygen and glucose. the conversion of light energy into chemical
energy by living organisms. The raw materials are carbon dioxide
and water. The energy source is sunlight, and the end-products
include glucose and oxygen.
6 CO2 + 12 H2O → C6H12O6 + 6 O2 + 6 H2O
Respiration: During respiration a plant
releases energy through chemical
reactions. This results in the break
down of sugar into oxygen, to carbon
dioxide.
Respiration is basically the opposite of
photosynthesis because it uses energy
and photosynthesis stores energy. It
uses food instead of producing food. It
uses carbon dioxide instead of oxygen
and it does not require light.
glucose + oxygen + water =
water + carbon dioxide + ENERGY
C6H12O6 + 6 O2 + 6 H2O → 6 CO2 + 12 H2O
Carbon dioxide enters the leaf through the
stoma, water travels up from the roots
through the xylem to the leaf. The
chloroplast absorbs sunlight/energy. The leaf
then uses the carbon dioxide
and water to produce
sugar (usable energy) that
travels through the
phloem to the rest of the
plant, and oxygen, that is
released back through the
stoma into the air.
Controlling Water LossThe leaf has a large
surface exposed to the air,
to keep moisture from
evaporating,
transpiration; too
quickly the leaf can close
the stomata. Pine needles
have less area exposed to
the elements and a thick
waxy coating to help
protect them and keep
them moist.
The Structure of Flowers : The function of all
flowers is reproduction. All flowers no matter
what they smell like or look like have the same
parts.
Sepals and petals when
a flower is a bud it is
covered by leaf like
structures called sepals
which are often green.
Under the sepals are the
colorful petals. The
shape, size and color
will vary between
varieties of flowers.
Stamen inside the
petals are the
reproductive parts of
the flower. The
stamen is male
reproductive parts.
They produce the
pollen and make sure
it is released where it
can be transferred to
the female parts.
Pistils found in the center of most flowers,
they are the female parts of the flower. Some
flowers have one pistil, some have two
Pollinators organisms that transfer pollen from
the male parts of a flower to the female parts.
Birds, bats, insects. Some are attracted by the
odor of the flower, some flowers smell sweet but
some smell bad.
Section TWO
Flower Parts
Petals are used to
attract insects into
the flower; they
may have guidelines
on them and be
scented. They are
brightly colored,
some pollinators are
attracted to certain
colors, other
pollinators are
attracted by scent.
Anther contain pollen sacs
where pollen is produced.
The sacs release pollen on
to the outside of the anthers
that brush against insects on
entering the flowers. The
pollen once deposited on
the insect is transferred to
the stigma of another flower
or the same flower. The
ovule is then able to be
fertilized.
Stigma Is
covered in a
sticky substance
that the pollen
will stick to.
Style raises the stigma
away from the Ovary to
decrease the likelihood of
pollen contamination. It
varies in length.
Ovary protects the
ovule and once
fertilization has taken
place it will become
the fruit. Contains
one or more ovule.
Pistils The female
reproductive part of the
flower. The parts of the
pistils are the sticky stigma,
the slender tube called the
style, and the hollow
structure called the ovary
at the base
Sepals are
small leaf like
structures; they
protect the
flower while the
flower is
developing
from a bud.
Anthers contain pollen
sacs where pollen is
produced. The sacs release
pollen on to the outside of
the anthers that brush against
insects on entering the
flowers. The pollen once
deposited on the insect is
transferred to the stigma of
another flower or the same
flower. The ovule is then
able to be fertilized.
Stamen Male
reproductive
part of the
flower. Pollen
is produced in
the anther
held high up
on the
filament