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WHAT IS A PLANT?
Objectives: By the end of this exercise you should be able to... 1. Describe 2 major functions each for roots, stems, and leaves. 2. Define and/or recognize major plant parts. 3. Recognize the differences between common dicots and monocots.
One of the essential aspects of science is careful, informed observation. This type of observation may be directed towards finding similarities and differences between organisms, or finding patterns in behaviors, growth, form, distribution, etc. The observations are then used to formulate questions, develop an hypothesis, and eventually test that hypothesis with an experiment, or further observations. You will be asked to do some careful observations of your own in this laboratory exercise.
Activity 1: Suppose you are asked to describe a plant to someone from another planet. What does a plant look like? What does a plant do? In the space below, draw your concept of a "typical" plant. Label its major parts, and write a brief explanation of the function of those parts next to each label. Compare your drawing with those of the other students in your group. On the overhead projector transparency sheet provided by the instructor, draw a composite of your group’s best ideas. We will compare these as a class.
Don't feel too badly if you don't know much about plants. Despite their tremendous importance in planetary ecosystems and our own human economy, we tend to emphasize animal biology in formal education and the media. Why do you suppose this is true?
Activity 2: Of course, there is no such thing as a typical plant, just as there is no one typical animal. Each student in your group should select a specimen from one of the plant groups at the back of the room, so that your group has one plant from Categories A, B, C, D, & E. Compare these plants to each other, and to your typical plant concept.
What similarities and differences do you see? Do your observations suggest any questions you would like answered? (e.g. do all plants have leaves?) Make a list of similarities/ differences, and questions to discuss with the class.
The plants in this activity are all from the Divisions Anthophyta (flowering plants), and Coniferophyta (conifers). A division is equivalent to a phylum, such as Chordata (chordates) or Arthopoda, in the animal kingdom. There are at least 16 more commonly recognized divisions in the plant kingdom, and much more diversity in form and species than we can show you in this exercise.
Activity 3: Learn the following terms, and be able to identify them on the plants provided. In addition, you should be able to distinguish the between the two major classes within the Anthophyta- the dicotyledons and monocotyledons.
herbaceous vs. woody
annual
perennial
stem node
internode
terminal or apical bud
axillary or lateral bud
simple leaf petiole
blade
sheath
stipule
compound leaf
leaflets
vein (vascular bundle)
leaf venation
parallel or netted
Common differences between dicots and monocots: Dicots - leaves with net venation, vascular bundles in one ring in stem, potential for woody growth, often with prolific branching, leaves do not continue to grow once expanded, flower parts in 4's or 5's, two cotyledons in seed. examples:
Monocots - linear leaves with parallel venation, leaf base is a sheath which encloses stem, no woody growth, on some, leaves may continue to grow once expanded (e.g. grasses), flower parts in 3's, one cotyledon in seed. examples :
Questions:
1. List 2 major functions for each of the following:
roots
stems
leaves
2. What is the difference between a simple leaf and a compound leaf?
3. Growth of the terminal (apical) bud ______________________ the stem.
Growth of a lateral (axillary) bud produces a ___________________.
4. List 4 differences between dicots and monocots.
5. Are grasses monocots or dicots?
Are trees and shrubs monocots or dicots?
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