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| Overview |
| Grade Level: 7-10 |
| Background Information:
Flowering plants have been on Earth for approximately 100 million
years. In that time, billions of varieties of plants have evolved.
All have the same basic characteristics, but each is different in
it's own way. According to the AFG video 'Seed Savers', there are
22,000 varieties of daisies alone. Plants have provided food and
medicine to humans since we arrived on Earth. However, daily we
are causing the destruction of species that we don't even know exist.
Our farming practices have also begun to cause a dramatic shift
in the populations of flowering plants. As agriculture has become
'big business' enormous areas are being devoted to one plant type,
such as corn or sunflowers. With the advent of genetically modified
organisms, the word monoculture has developed new meaning. Today,
organisms that share the same genotype cover many square miles of
land. A basic understanding of Mendellian heredity will allow students
to understand the implications of these changes to our ecosystem.
In this lesson, students will look carefully at flowering plants.
They will study basic Mendellian heredity in the light of flowering
plants and they will learn how seed savers work to save diversity.
Finally, they will compare scenarios in which genetically diverse
fields and fields planted with GMOs undergo various natural challenges.
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| Content Standards |
| Related National Standards:
This lesson addresses the following National Content Standards
found at: http://books.nap.edu/html/nses
Content Standard C: As a result of their activities in grades
5-8, all students should develop understanding of:
- Reproduction and Heredity
- In many species, including humans, females produce
eggs and males produce sperm. Plants also reproduce
sexually - the egg and sperm are produced in the flowers
of flowering plants. An egg and sperm unite to begin
development of a new individual. That new individual
receives genetic information from its mother and its
father. Sexually produced offspring are never identical
to either of their parents.
- Every organism requires a set of instructions for
specifying its traits. Heredity is the passage of these
instructions from one generation to the next.
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Content Standard C: As a result of their activities in grades
9-12, all students should develop understanding of:
- The Molecular Basis of Heredity
- In all organisms, the instructions
for specifying the characteristics of the organism are
carried in DNA, a large polymer formed from subunits
of four kinds. The chemical and structural properties
in DNA explain how the genetic information that underlies
heredity is both encoded in genes and replicated.
- Biological Evolution
- Biological classifications
are based on how organisms are related.
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Content Standard F: As a result of their activities in grades
9-12, all students should develop understanding of:
- Natural and Human-Induced Hazards
- Some hazards, such as earthquakes,
volcanic eruptions, and severe weather, are rapid and
spectacular. But there are slow and progressive changes
that also result in problems for individuals and societies.
- Natural and human-induced
hazards present the need for humans to assess potential
danger and risk. Many changes in the environment designed
by humans bring benefits to society as well as cause
risks.
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| Extension Web Sites
from PBS: |
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PBS
TeacherSource - Mathline
This website instructs students to develop a flower garden using
percentages.
Newton's
Apple - Ethnobotony
In this activity, students learn how archaeologists study the foods
of past peoples.
Scienceline
- How plants sense the environment
This site contains an easy to read overview of an experiment that
shows how, even though plants don't have eyes, ears, nose, etc,
they can still sense the environment.
Wild
Indonesia - Seed Dispersal
Learn how seeds distribute themselves by hitching a ride with animals.
Science
Safari - Mr. Cele's Garden
Experiment with seeds to determine factors that influence germination
while learning about plant diversity on our planet.
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| Activity 1: Plant Classification |
| Time Allotted:
20 minutes
Materials:
Students will be assigned to bring five flowers. The teacher may
wish to have some spares in case students forget.
| Objectives: |
- Students will explore flowers to distinguish different
physical features of flowers.
- Students will compare and contrast different flowers to
determine what features they have in common.
- Students will learn the rudimentary basis for biological
classification of plants.
- Students will develop an appreciation for the diversity
of flowering plants.
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| Teaching Instructions |
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Note: this activity depends on the use of fresh flowers,
thus it should be conducted at a time of year when flowers
are blooming abundantly in your area.
- Students should each make a collection
of five different flowers to bring in to the classroom.
This step should be assigned in advance as homework.
- Divide students into groups of
two, between them, they should have ten flowers.
- Ask them to make two lists while
looking over the flowers. One should be of features common
to all the flowers; the other list should be differences
between the flowers.
- Tell them that they need find
a way to classify their flowers, breaking them into between
three and five groups based on some physical feature. These
may include color, shape, size, petal type, leaf type, or
any other division that makes sense to the students.
- Have students share their classification
systems with the class. Or have them make a small poster
with the flowers and their classification system. Discuss
other possible methods for classification of plants (bloom
time, temperature tolerance, geographical distribution for
example).
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Watch the AFG Video Segments:
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Appalachian
Cove, South Carolina - Spring Flowers
Flowering
plants attract pollinators with their brightly-colored petals,
as well as with other methods. |
| Discussion Questions for Video Segment: |
- Did you see any of the features that you identified during
this lab that had developed in a different way?
- They mentioned that 'It takes a lot of energy to flower'.
Many plants can be propagated as well using asexual reproduction.
Why do plants go to the effort of flowering if it takes
so much energy?
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| Extension Activities: |
- From here you may wish to have students learn the specific
parts of flowers to teach them about sexual reproduction
in plants.
- Or see the AFG lesson on insects for other related activities.
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| Activity 2: Seed Savers and
Genetic Inheritance |
| Time Allotted:
One 45-minute class period
Materials:
Student Instruction Sheet
| Objectives: |
- Students will calculate likelihood of different genetic
combinations to understand the basis for heredity.
- Students will illustrate the effects of dominant and recessive
genes. · Student will learn how human interference can change
natural ratios in plant populations.
- Students will gain an appreciation of the difficulty of
crossbreeding and maintaining seed populations.
- Students will develop an appreciation for maintaining
genetic diversity.
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| Teaching Strategies |
- Students should be introduced to the concept of Mendelian
inheritance before beginning this lesson.
- Divide class into groups of two and distribute student
instructions.
- Unless students have extensive experience working with
Punnett squares, it is recommended that you work through
the first part of the activity with them. These are very
logical, so some students will find them fun and easy while
others may be very frustrated. Then have them complete part
two of the handout.
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Watch the AFG Video Segment:
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Seed
Saver
In
order to maintain genetic diversity among food, plants and flowers,
many conscientious people are saving seeds. |
| Discussion Questions for Video Segment:
After the students have had a chance to complete the student
handout, discuss the following:
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- Why do farmers work hard to create hybrids?
- Why do some farmers go through such efforts to maintain
diversity?
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| Assessment: |
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A solution key for this activity is available in the PDF
version of this lesson.
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| Activity 3: Biodiversity
and the Future of Flowering Plants |
| Time Allotted:
One 45-minute class period
Materials:
Student Instruction Sheet
| Objectives: |
- Students will calculate the effects of various disease
scenarios on two populations of sunflowers to learn about
the importance of biodiversity.
- Students will develop an understanding of the dangers
associated with monocultures.
- Students will weigh the pros and cons of genetically modified
organisms.
- Students will learn to appreciate the value of biodiversity.
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Watch
the AFG Video Segment:
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Wildflowers
at Mammoth Cave - Part 1
A
naturalist who began studying flowers as a hobby has documented
over 300 species of plants and flowers at Kentucky's famous
Mammoth Cave. |
| Discussion Questions for Video Segment: |
- How many species of wild plants have been found in this
area? · What were some of the uses for the plants found
around Mammoth Cave?
- Why is maintaining genetic diversity important?
- What consequences might there be if large numbers of rare
wild plants go extinct? (point out that they are going extinct
at a rapid rate, especially in rainforest areas).
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| Classroom Activity: |
- Divide class into groups of two or three. Hand out student
instructions and color copies of field diagrams. Help students
understand the scenario and introduce the concept of genetically-modified
organisms.
- Discuss answers to student questions.
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| Assessment: |
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A solution key for this activity is available in the PDF
version of this lesson.
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