Download From Seed to Shining Seed

Grade: 9 to 12
Introduction
Length: variable
Subjects: life science
Topics: weed identification
Objectives
Exercises in this lesson help students achieve the
following objectives:
Understand the basic parts of a plant
Like most plants, weeds have four major parts:
roots, stems, leaves, and flowers or seeds. Individual parts comprise each of the four major parts,
and each part has a specific function. Students will
learn about the parts of a plant and stages of plant
development by planting bean seeds and observing the plants as they grow through all stages of
development, until the plant produces seeds. Before teaching this lesson, read the entire lesson and
make sure all materials are available.
Understand how the basic parts of a plant work
together
Follow the growth cycle of a plant from the
seed stage to the production of a new seed
Diagram of a Typical Plant
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Background
Roots
Roots serve the following three major functions:
Anchor the plant in the soil
Absorb water and nutrients
Store food
Roots have a number of different components that
help achieve these functions. Tiny root hairs absorb water and nutrients. Each root hair has a root
cap to protect the root hair as it pushes through
the soil. Behind the root cap is a zone of cell division. Behind the zone of cell division is the zone
of cell elongation, where roots lengthen. Root
growth takes place in these two zones. The meristematic zone includes the root cap and the zone
of cell division.
The xylem transports water and minerals from the
roots to the stem. Xylem tissue consists mainly of
hollow tubes. The phloem carries food from the
leaves to the roots. Cambium tissue is the living
part of a stem. Cell division takes place in the cambium.
The arrangement of the xylem and phloem and the
location of the cambium are different in monocotyledons and dicotyledons.
Cross-section of a
monocot stem
Cross-section of a
dicot stem
Cross-section of a stem
Leaves
Leaves serve the following three major functions:
Produce food for the plant
Diagram of a Root
Store food
Take in and let out various gases
Stems
Stems serve the following three major functions:
Transport water and minerals from the roots to
the stem and food from the leaves to the roots
Hold the plant erect so the leaves can reach the
sunlight
Store food
A plant produces food through a process called
photosynthesis. During photosynthesis, a plant
uses sunlight to produce glucose or food. Specifically, a plant uses sunlight, carbon dioxide, and
water to produce glucose. A plant produces oxygen
as a waste product. Plants contain a chemical called
chlorophyll, which makes photosynthesis possible. In most plants, chlorophyll is green in color,
and tiny structures called chloroplasts contain the
chlorophyll.
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A plant must have energy to live. The plant obtains
its energy by breaking down glucose through a
process called respiration. Respiration is the reverse of photosynthesis. (See the illustration Respiration and Photosynthesis on page 122.)
Plants continuously transport water to the leaves
from the roots. Leaves release water vapor and
other gases through openings called stomata. This
process is called transpiration. Through transpiration, water comes into the plant, and transpiration
keeps the plant cool during hot months.
To carry out these complex functions, leaves have
developed an amazing structure.
coat disintegrates, a root hair emerges and begins
to absorb water and nutrients, and seed leaves
emerge and grow toward the sunlight.
plumule
radicle
(develops into the
stem and leaves)
(develops into
a root)
seed coat
cotyledon
Bean Seed Cross-section
Characteristics of plants
Each weed has specific characteristics that help
botanists identify the weed. Some characteristics
are difficult to identify; others are obvious. The following characteristics are some of the more obvious characteristics botanists use to identify weeds:
Flower color
Leaf Cross-section
Flower arrangement on stem
Vein arrangement in leaves
Flowers and seeds
The major function of flowers is to help in sexual
reproduction. Some parts of a flower, such as the
petals, nectar, and perfume, attract bees and other
insects. The male part of the flower is the stamen,
which is comprised of the filament and anther. The
anther holds pollen. The female part is the pistil,
which is comprised of the stigma, style, and ovary.
When insects land on flowers, they transfer pollen
from the anther to the stigma. The pollen moves
down the style and fertilizes the egg. Once fertilized, the egg becomes a seed, and the flower dies
and drops off.
The seed contains a living embryo. A seed coat encloses the embryo and protects the embryo until it
is ready to germinate. The seed also contains seed
leaves (cotyledons) and stored food (endosperm).
The seed remains dormant until conditions are
ideal for growth. Under ideal conditions, the seed
Blade type
Leaf arrangement on stem
When identifying a weed, the color of the flower
is one of the first characteristics botanists notice.
However, many weeds have the same color of
flower. Flower arrangement on the stem is the next
characteristic botanists look for. Other identifying
characteristics that botanists use include leaf shape,
leaf margins, shape at the base of the blade, and
shape of the blade tips.
Preparation
Materials
bush bean seeds – Have available 10 seeds for
every two students.
paper towels
plastic sandwich bags
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Leaf Arrangements
Flower Arrangements
Leaf Venation
Leaf Types
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potting soil with time-release fertilizer
4-inch pots – Have available at least two pots
for every two students.
greenhouse, window, or other growing area
dissecting microscope or hand-held lens
copies of Life cycle of a Bean Plant, Plants and
Their Parts, and From Seed to Shining Seed
Weed Journal Entries worksheets – Have available one copy for each student
student Weed Journals
all the materials listed above.
1 Assemble
Students will use these items during the
Activity. Give each student a copy of each
worksheet.
Activity
students into teams of two students per
1 Divide
team. Discuss the Plants and Their Parts and
Life cycle of a Bean Plant worksheets.
2
To observe the emergence of roots and
determine seed viability:
A.Instruct each team to place 10 bean seeds on
a wet paper towel, and place the paper towel
in a sandwich bag.
B. Seal the bag and place it in a warm location.
C. As roots emerge, ask students to record
their observations on the From Seed to Shining
Seed Weed Journal Entries worksheet.
D.After seeds have germinated, ask students
to calculate the percentage of viable seeds.
E. Discuss the germination process to ensure
students understand the process.
students carefully transplant at least
3Have
two of the germinated seeds into 4-inch pots
containing potting soil with slow-release fertilizer.
students to record emergence of the
4Instruct
cotyledons and all stages of plant growth and
development.
one of the flowers and study it under
5Remove
a dissecting microscope.
the flowering stage, shake flowers to
6During
ensure cross-pollination.
Conclusion and Evaluation
Conclude the lesson when the plants produce
beans and students have harvested the seeds.
Evaluate students on their ability to identify
weeds using the physical properties outlined
earlier in this lesson. Or use the Weedy Crossword Puzzle as a quiz.
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Independent Practice and Related
Activities
Most commercial bean seeds are hybrids. Seeds
from hybrids are not as viable as seeds from the
parent plants, and hybrid plants are not as hardy as the parent plants. To demonstrate these
characteristics, harvest the bean seeds, dry the
seeds, and plant them. Calculate the percentage
of viable seeds.
Vocabulary
alternate, anthers, blade, cambium, chlorophyll,
chloroplasts, corymb, dicotyledon, dormancy,
embryo, epidermal cells, glucose, guard cells,
internode, meristem, monocotyledon, node, opposite, ovary, palmate compound, parallel, phloem,
photosynthesis, pinnate, pinnate compound, pistil,
plumule, pollen, pollination, raceme, radicle, respiration, root cap, root hairs, roots, rosulate, seed,
sexual reproduction, simple, spike, stamen, stems,
stigma, stoma, style, transpiration, umbel, vena-
tion, whorled, xylem, zone of cell division, zone of
elongation
Resources
Peterson, Roger Tory and Margaret McKenny. A
Field Guide to Wildflowers of Northeastern and
North-central North America. Boston: Houghton
Mifflin Company, 1968.
National Science Education
Standards
As a result of their activities in grades 9 to 12,
students should develop an understanding of and
abilities in the following areas:
Science as Inquiry – Content Standard A: scientific inquiry, understandings about scientific inquiry
Life Science - Content Standard C: matter, energy,
and organization in living systems; behavior of
organisms
Solution to Weedy Crossword
Across
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Phloem
Spike
Embryo
Stoma
Respiration
Dicot
Photosynthesis
Corymb
Stem
Umbel
Germinate
Transpiration
Monocot
Raceme
Stigma
Pinnate
Cotyledon
Whorl
Alternate
Leaves
Palmate
Nodes
Down
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Petals
Meristematic
Stamen
Endosperm
Root cap
Anther
Roots
Xylem
Filament
Solitary
Seed
Elongation
Internode
Opposite
Stomata
Simple
Style
32. Ovary
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Life Cycle of a Bean Plant
Germination
Germination occurs underground when sufficient water, oxygen,
and heat are present. The seed coat swells and then starts to disintegrate. A tiny root (radicle) appears, followed by a tiny stem (plumule).
Growth
Approximately 5 to 7 days after planting, the first leaves—two
oblong seed leaves (cotyledons)—emerge from the soil. As the plant
continues to grow, true leaves begin to appear.
radicle (develops
into root)
plumule (develops
into the stem and
leaves)
seed coat
cotyledon
Reproduction
After about 3 weeks, the first flowers appear. These flowers are
white and solitary. If conditions are suitable for pollination, the
flowers fade after 3 to 4 days. In the center of the flower, a small bean emerges. As the bean grows, the
flower petals fall off. The bean pod continues to grow until it reaches a length of 3 to 4 inches.
Seeds
Once the pod is fully grown, it will contain 4 to 7 new bean seeds. Plant these seeds, and begin the whole
process again.
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Plants and Their Parts
Diagram of a root
Diagram of a typical plant
Cross-section of a
monocot stem
Cross-section of a
dicot stem
Leaf cross-section
Cross-section of a stem
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Weedy Definitions
alternate – leaf arrangement in which each leaf is
attached at a different level on the stem
anther – the head at the top of the filament where
pollen forms
blade – the flat part of a leaf; to physically scrape
an area with a blade to remove weeds
cambium – tissue that forms the living part the
stem; where cell division takes place in the stem
chlorophyll – a green-colored chemical that converts the sun’s energy to food through the process
of photosynthesis
chloroplasts – sacs in plant cells that contain chlorophyll
corymb – a flat flower head consisting of flowers
whose stalks grow from different points on the
flower stem but reach approximately the same
height
dicotyledon – a flowering plant that produces two
seed leaves when it germinates and whose subsequent leaves have a network of veins
dormant – in an inactive state, when growth and
development slow or cease, in order to survive
adverse environmental conditions
embryo – a plant in its earliest stages of development; in seed-bearing plants, the embryo is contained within the seed
epidermal cells – the outermost layer of cells
glucose – a sugar produced by plants through
photosynthesis
guard cells – cells that surround the stoma
internode – the distance between nodes
meristematic zone – composed of the root cap and
the zone of cell division
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monocotyledon – a flowering plant that has a
single leaf in the seed and floral parts in multiples
of three
node – composed of the leaf axil and bud
opposite – leaf arrangement in which two leaves
are attached at one level but on different sides of
the stem
ovary – where seeds develop at the base of a flower
palmately compound – leaflets attached at the end
of a stalk, spreading like fingers on a hand
parallel veining – veins that run alongside each
other and never intersect
phloem – a tube that carries food from the leaves to
the roots
photosynthesis – process through which plants use
sunlight, carbon dioxide, and water to make glucose and oxygen
pinnately compound – leaflets arranged around a
central stalk
pistil – the female reproductive part of a flower,
composed of the ovary, style, and stigma
plumule – the rudimentary primary shoot of a
plant embryo
pollination – the process of transferring pollen
from the anther to the stigma to fertilize a plant
raceme – a flower cluster in which the flowers are
borne on short stalks along a long main stem
radicle – the part of a plant embryo that forms the
root of the young plant
respiration – the process through which plants
break down glucose to make energy; the reverse of
photosynthesis
root cap – protects the root hair
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Weedy Definitions
root hairs – absorb water an nutrients
roots – function to anchor a plant, absorb water
and nutrients, and store food
rosulate – leaf arrangement in which leaves are attached around the base of the stem
seed – the body produced by reproduction in most
plants that contains the embryo and produces a
new individual
sexual reproduction – natural process by which
some plants and animals produce offspring as a
result of fertilization of the egg from another plant
or animal
simple – a leaf that is not divided, either totally or
partially, into separate segments
spike – a long cluster of flowers attached directly
to a stem, with the newest flowers at the tip
stamen – the male reproductive organ of a flower,
composed of the anther and the filament that holds
the anther
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stomata – ventilation holes in a leaf that take in
carbon dioxide and release oxygen
style – stem-like extension of the ovary through
which a pollen tube grows down into the ovary
carrying the pollen necessary for fertilization
transpiration – the process of evaporation from a
plant’s leaves
umbel – a flower cluster that has a number of
branches all attached at one point
venation – the pattern of veins
whorl – a leaf arrangement in which three or more
leaves are attached in a ring at one level
xylem – a tube which transports water and minerals
zone of cell division – the place in the root where
cells divide
zone of cell elongation – the place in the root
where cells become larger
stem – the main trunk of a plant
stigma – the sticky top of the style that collects pollen
Respiration and photosynthesis
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From Seed to Shining Seed
Weed Journal Entries
Event
Date
Observations
Number of seeds planted ______
First radicle appears
First seed leaves appear
number of seeds germinated _____
Last seeds germinate
% viability _______
Seedlings transplanted
Height of plant
Height of plant
Height of plant
Height of plant
Height of plant
Height of plant
Height of plant
First flowers appear
First bean pods appear
Bean pods appear
Bean pods appear
Bean pods appear
Bean pods appear
Bean seeds harvested
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Weedy Crossword Puzzle
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Across
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Carries food from the leaves to the roots
Long cluster of flowers attached directly
to a stem, with the newest flowers at the
tip
Plant in its earliest stages of development
Leaves release gases through this opening
Process through which plants break
down glucose to make energy
Flowering plant that produces two seed
leaves when it germinates
Process through which plants use sunlight, carbon dioxide, and water to make
glucose and oxygen
Flat flower head consisting of flowers
whose stalks grow from different points
on the flower stem but reach about the
same height
Transports minerals and water from
the roots to the stem and food from the
leaves to the roots
Flower cluster with branches all attached
at one point
To grow from a seed into a new plant
Process through which plants bring
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water to the leaves from the roots and
release gases from the leaves
Flowering plant that has a single leaf in
the seed
Flower cluster in which flowers are on
short stalks along a long main stem
Sticky top of the style that collects pollen
Arranged along a central stalk or stem
Seed leaves within a seed
Leaf arrangement in which three or more
leaves are attached at different levels on
the stem
Usual leaf arrangement where leaves are
attached at different levels on the stem
Produce food for the plant and take in or
let out gases
Leaves or veins which spread like fingers on a hand
Consist of leaf axils and buds
Down
Showy colored parts that form the outer
part of a flower
This zone is made of the root cap and
the zone of cell division
Composed of an anther and filament
Stored food within a seed
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Protects root hairs as they push through
soil
Head where pollen forms at the top of
the filament
Anchor plants in soil and absorb water
and nutrients
Part of the stem that transports water
and minerals
Stalk-like part of the stamen
Flower that grows singly rather than as
a cluster
Body produced by reproduction in most
plants that contains the embryo and
produces a new individual
In this zone, cells become larger
Distance between nodes
Leaf arrangement where leaves are attached at one level on different sides of
the stem
Plural of 7 Across
Leaf that is not divided, either totally or
partially, into separate segments
Stem-like extension of the ovary through
which a pollen tube grows down into
the ovary carrying the pollen necessary
for fertilization
Seeds develop here
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