Download Seed Plants - Elmwood Park Memorial Middle School

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Chapter 5- Seed Plants
Section 1- Characteristics of Seed Plants
What is a Seed Plant?
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All seed plants share two characteristics: they have vascular tissue and
use seeds to reproduce.
Vascular Tissue
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Vascular tissue gives the plant the ability to stand upright, gives support,
and transports materials throughout the body.
There are two types of vascular tissue:
a. Phloem- this transports food.
b. Xylem- this transports water and nutrients.
Seeds
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A seed has 3 important parts:
a. An embryo- the fertilized egg (zygote) that contains the beginnings of
the root, stem, and leaves.
b. Stored Food- what the plant uses as energy until it can make its own.
Sometimes this is stored in 1 or 2 leaves (cotyledons).
c. A seed coat- an outer covering that protects the seed and protects it
from drying out.
Seeds need to spread out from the parent plant and can do that in 5
ways:
a. Animals eat the seeds, digest it, and deposit it in a new spot.
b. Some seeds can hook onto fur or clothing to be deposited in a new
spot.
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c. Water can transport the seed to a new location (through rivers,
oceans, streams, etc.).
d. Some plants shoot out their seeds.
Germination starts when the seed gets water from the environment.
The embryo then uses the stored food to begin growing. Roots grow
downwards first and then leave grow upwards.
Leaves
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Leave capture the sun’s energy and carry out the food making process of
photosynthesis.
The structure of a leaf are:
a. The top and bottom layer is the cuticle, which protects the leave and
helps retain water.
b. Between the layers contain the xylem and phloem.
c. Under the leaf are small pores that can open/close called the
stomata. These allow carbon dioxide in and allow oxygen and water
vapor out.
The Leaf and Photosynthesis
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Photosynthesis occurs in the chloroplast, which are located near the
leaf’s upper surface where they are closest to the sun. They trap the
sun’s energy.
Carbon dioxide enters through the stomata.
Water is brought up by the xylem.
Sugar and oxygen are produced in a chemical reaction.
Oxygen is released by the stomata.
Sugar is transported throughout the plant by the phloem.
Controlling Water Loss
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Stems
Water can be lost from a plant in a process called transpiration. This can
be controlled by opening or closing the stomata.
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The stem carries substances between the plant’s roots and leaves. The
stem also provides support for the plant and holds up the leaves so they
are exposed to the sun. Some stems store food.
There are two types of stems:
a. Herbaceous- a soft, pliable type of material.
b. Wood- a hard, rigid material. This is also made up of bark (outer
layer) and heart wood (inner layer). As well as the pith (which stores
food/water) and the cambium (cells that produce the xylem and
phloem).
Both consist of the phloem and xylem.
Annual rings consist of new layers of xylem. One can tell about the
year’s growth (moisture, weather conditions, etc.) by the rings of the
tree.
Roots
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Roots anchor a plant to the ground and absorb water and nutrients from
the soil.
There are two type of roots:
a. Taproot- consists of a long, thick main root and thin, branchy toots
that grow off the main root (like turnips, dandelions, cacti).
b. Fibrous- consists of several main roots that branch to form a tangled
mass (like grass and trees).
There are 5 structures that make up the root:
a. The root cap- the rounded end of a root made up of dead cells that
protect the root as it grows.
b. Area of dividing cells- which causes the root to lengthen/grow.
c. Root Hairs- which grow off the root and increase the surface area so
more water/nutrients can be absorbed and anchors the plant.
d. Vascular Tissue- where substances are taken by the phloem/xylem to
the rest of the plant.
e. Cambium- which produces new phloem/xylem.
Key Vocabulary: phloem, xylem, seed, embryo, cotyledon, germination,
stomata, transpiration, cambium, root cap.
Section 2- Gymnosperms
What Are Gymnosperms?
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All gymnosperms share 3 characteristics:
a. The production of “naked” seeds- not enclosed by any protective
covering.
b. Needlelike/scale like leaves.
c. Deep growing roots.
Types of Gymnosperms
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They are the oldest type of seed plant and are classified into 4 groups:
a. Cycads- found in tropical areas that look like palm trees with cones.
b. Ginkgo- can grow to 25 meters and the only type still alive today is
the Ginkgo Biloba trees.
c. Gnetophytes- they live in hot, dry deserts of Africa, southwest US,
and tropical rainforests. Some are trees, some are shrubs, and some
are vines.
d. Conifers- they largest/most diverse group of gymnosperms. They
keep their leaves all year round and are cone bearing plants.
Reproduction
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Typically the gymnosperms reproduce in cones- male and female. First,
pollen falls from a male cone onto a female cone. In time, a sperm cell
and an egg cell join together in an ovule on the female cone. The zygote
develops into the embryo part of the seed.
Pollination and Fertilization
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Wind carries the pollen (sperm cell) to the ovule and collects on the
sticky substance. The female cone then closes to seal in the pollen.
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The seeds form on the female scale and the cone stays on the tree until
they are mature. The male cone falls after the pollen is shed.
Seed Dispersal
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Cone containing immature seeds point upwards and mature seeds point
downward.
When the seeds mature, the scales open and are taken away by the
wind.
Gymnosperms and the Living World
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Gymnosperms are used to make many products, like paper, wood for
homes and furniture, clothing, turpentine, etc.
They are grown in large forests in the US for clear cutting, which can
leave many creatures homeless and cause soil erosion. Sometimes trees
are grown or cut in strips to help prevent these problems.
Key Terms: gymnosperm, cone, pollen, ovule, pollination
Section 3- Angiosperms
What are Angiosperms?
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Two characteristics of angiosperms are that they produce flowers and
fruit. They are typically the most familiar plant around us.
The Structure of Flowers
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Many flowers are similar and different but they typically have the
following structures:
a. Sepal- the leaf like structure that protects the developing flower.
b. Petals- the colors, shapes, and odors produced in these structures
attract insects and other organisms to help with pollination.
c. Stamen- the male reproductive part that is typically made of:
i. Filament- the thin stalk.
ii. Anther- the knob at the top of the stalk where pollen is
produced.
d. Pistil- the female reproductive part that is typically made of:
i. Stigma- the sticky top part.
ii. Style- the slender tube that connects the stigma and the base
of the flower.
iii. Ovary- the hollow structure that contains one or more ovules.
Reproduction
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First, pollen falls on the stigma. In time, the sperm cell and egg cell join
together in the flower’s ovule. The zygote develops into the embryo
part of the seed.
Angiosperms can be pollinated by the wind, birds, or insects which get
the pollen on their bodies when they come to get the nectar. They
transfer the pollen to the egg cell.
As the seed develops, the ovary changes into a fruit, which can encase
more than one seed. This is a way in which it disperses the seed.
Types of Angiosperms
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They are divided into 2 main groups:
a. Monocots- meaning “one”, these only have one seed leaf. They have
flowers with either 3 petals or multiples of 3. The leaves have
parallel veins and scattered vascular tissue.
b. Dicots- meaning “two”, these have two seed leaves. They have
flowers with 4 or 5 petals or multiples of these numbers. Their
leaves are wide with netted veins and bundles of vascular tissue
arranged in a circle.
Angiosperms in the Living World
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Angiosperms are used for food, clothing, and medicine.
Key Terms: angiosperm, ovary, flower, petal, sepal, stamen, pistil, fruit,
monocot, dicot
Section 4- Plant Responses and Growth
Tropism
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Touch, light and gravity are three important stimuli to which plants
respond. Moving towards stimuli is positive tropism. Moving away
from stimuli is negative tropism.
a. Thigmotropism- the response to touch, like a coiling vine.
b. Phototropism- the response to light, like bending/growing towards
light.
c. Gravitropism- the response to gravity, like roots growing downwards.
Plant Hormones
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In addition to tropisms, plant hormones control germination, the
formation of flowers, stems and leaves, the shedding of leaves and the
development and ripening of fruits.
One type of hormone is auxin, which reacts to light and helps the plant
to grow at a faster rate.
Life Spans of Angiosperms
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Annuals are flowering plants that complete a life cycle in one year and
typically have herbaceous stems (like tomatoes and marigolds).
Biennials are plants that complete a life cycle in two years. The first
year, they grow roots, short stems, and sometimes leaves. The second
year, they grow new stems, leave, flowers and seeds (like parsley and
celery).
Perennials live more than two years. They typically have woody stems
(like trees, honeysuckle, asparagus, and peonies).
Key Terms: tropism, hormone, auxin
Section 5- Feeding the World
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In factories, scientists are developing plants that are resistant to insects,
disease, drought, and that produce more food per plant. There is also
new, efficient, “high tech“farming practices being used.
Producing Better Plants
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Scientists genetically engineer bigger crops or bigger produce by
changing the plants’ genetic material.
Genetic engineering also can alter where plants can grow, how they are
affected by insects, or how they are affected by disease.
Improving the Efficiency on Farms
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Tools are being developed to help farmers know how much water/
fertilizer are needed, what the soil is like, and what a crop might need.
The thought is to help farmers save time and money, as well as increase
how much a crop can grow. It can also help the environment so as to
not over fertilize.
Hydroponics
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Plants can be grown in solutions of nutrients instead of poor soil. This
can help in areas where growing conditions are not ideal.
This method can be costly.
Key Terms: genetic engineering, hydroponics