flowers by lovemacromastia

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									Flowers: Form and Function
Based upon a lesson by Roxane Johnson
Modified by Kirstin Bittel and Rachel Hughes
http://biology.arizona.edu/sciconn/lessons2/Roxane/flow.htm

Time :                        1 class period
Preparation Time :            Collecting flowers, loupes, fruits and seeds.
                              Photocopying student sheets.
Materials :                   Flowers for each students (Flower shops often
                              will be very generous with flowers that have
                              seen better days- make sure they are simple
                              flowers not composite flowers)
                              Eye loupe
                              Fruits and seeds


Abstract
In this dissection lab, students will use eye loupes or magnification lenses to look closely at
flowers. As the flower is dissected, students determine the function of each part by observing the
form. Intermittent use of plant videos can be shown to reinforce what is being seen in the
dissection.

Objectives
Students will be able to:
    1. Recognize and name the parts of a flower
    2. Explain the function of each part of a flower
    3. List the steps that occur for sexual reproduction of a plant to take place
    4. Recognize and name the male reproductive parts, and female reproductive parts of a
       flower

National Science Education Standard:
Content Area C – The Interdependence of Organisms
Organisms both cooperate and compete in ecosystems. The interrelationships and
interdependencies of these organisms may generate ecosystems that are stable for hundreds or
thousands of years.

Teacher Background
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookflowers.html
http://www.biologie.uni-hamburg.de/b-online/e02/02f.htm

Related and Resource Websites
http://www.saburchill.com/chapters/chap0042.html
http://www.learn.co.uk/default.asp?WCI=Unit&WCU=2330


Activity
1. On each group’s desk have a beaker containing a mixture of flowers, a seed and an item easily
identifiable as a fruit. The presence of the flowers is often a good catch for students. Ask them to
describe either in words or pictures the relationship between flowers, fruits and seeds. Notebook
Preassessment
2. Begin the flower dissection by handing a flower to a student. Ask him/her to make observations
and to describe it. Hand it to another student. Continue to have students describe it until no other
observations can be made. While students are describing the flower, have a student write the
observations on the board or overhead.
What is likely to occur is that students will want to describe a particular feature of the flower but
won’t have the term for it. Don’t give them the term yet. Have them just describe it. (Later they will
make the connection with the terms they are given.) This is a good point to introduce the idea of
flower anatomy- that each flower part has a name so scientists can talk about flowers using the
same language. It also helps botanists to categorize and identify flowers because of the color and
shape of particular parts. Tell students that they will be taking apart a flower today so they can
understand how and why a flower functions as it does.

4. Students observe their own flower, describing it and drawing it in their notebooks, labeling the
parts as they are identified.

    5. Pass out a flower to each student. Once all students have a flower, ask them, "Why do
        flowers have petals?" They’ll probably know that they are for attracting pollinators. It’s the
        flower’s way of dressing up. Explain that all the petals together are called the corolla- a
        word related to the word corona meaning garland or crown.
    6. The teacher should begin with the petals then have the students remove and count the
        petals of their flowers, taking note of this in their journals. Now the sepals, peduncle,
        receptacle, stamens and pistils should be visible. One by one draw the students’ attention
        to each of these areas. Have them use their eye loupes to look closely and to draw
        diagrams of each part. Ask what they think each part is for. (They will be able to see that
        the sepals once were the covering for the bud, and notice that the peduncle supports the
        base of the flower.)
    7. Give the students time to use color pencils to make distinctions in their drawings. Give
        them opportunities to ask questions and clarify understanding.
    8. Have the students remove one entire pistil (they may have to dig down to get the ovary)
        and look at it closely. Look at the stigma, style and ovary. They can even open the ovary
        and look inside. They should draw, label and write the function of each part. Do the same
        with the stamens, anther and filament.
    9. Having identified the anthers, stamen and stigma ask students how they think pollen gets
        from the anthers to the stigma. Introduce the idea that it is more beneficial for plants to
        cross pollinate, that plants are designed to have pollen move from one plant to another.
        Looking at the flowers in front of them can students identify how pollen might move from
        one plant to another? Have students suggest methods of pollination. Provide the
        definition that pollination is the movement of ripe pollen to a ripe stamen.
    10. Provide students with the attached chart. Students should be able to suggest wind, water,
        insect and bird as vectors for pollination. Have them observe the flowers again and
        identify what factors are necessary for which type of pollination. Once the class has
        correctly identified a structure as appropriate for a type of pollination they should note
        that in the chart also. Direct students to the website:
        http://www.learn.co.uk/default.asp?WCI=Unit&WCU=2330 This website has some simple
        diagrams that will support students’ comprehension of pollination. Students should draw
        flowers on their charts that represent each form of pollination.




    Assessment:

    Have students identify the parts of an unknown flower. They should make suggestions as to
    how the male and female structure organization plays a role in pollination.
Pollination
The process by which ………………………………………………………………………………….

Type of Pollination   Structures associated   Example of flower   Does the plant have
                      with this type of                           specific ways of
                      pollination                                 attracting pollination?

								
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