Life Cycle - Plants (2B)
Lab 

   
OBJECTIVES:
  • Classifying broad and needle leaf trees.
  • Comparing and contrasting gymnosperms and angiosperms.
VOCABULARY:
  • angiosperm
  • flower
  • gymnosperm
  • pine cone
  • pollen
MATERIALS:

Students classify specimens.


example of gymnosperm

BACKGROUND:

Angiosperms produce specialized structures called flowers in which seeds develop. Angiosperms are the dominant members of the world's flora. Angiosperms are flowering and fruit producing plants. The angiosperms may be divided into the monocots and the dicots. Seeds and fruits may be variously modified, a factor that frequently assists in seed dispersal. Wind, animals, (including humans), and water are the most important agents of dispersal.

Gymnosperms produce unenclosed seeds located on the upper surface of scales, which are usually parts of cones. Most conifers are woody plants and are usually large with leaves that are usually evergreen needles or scales. Conifers are the most abundant gymnosperm today. Pines, spruce, fir, cedars, sequoias, redwoods, and yews are all conifers. Conifers cover large areas of North America, China, Europe, and Australia. The leaves of conifers are long and thin, and are often called needles. Even though the name evergreen is commonly used for these plants, it isn't accurate because needles don't remain on conifers forever.

Conifers have male and female reproductive structures called scales. Scales are grouped into larger structures called male and female cones. Male cones make male gametophytes called pollen. Female cones make female gametophytes called eggs. Later, the female cones hold seeds that develop on their scales. Each seed is covered by a seed coat, but the seed isn't protected by the cone. Since the seeds sit "naked," or on the outside of the scales, conifers are called naked seed plants, or gymnosperms ("gymno" means naked; sperm means seed).

PROCEDURE:

Most students are familiar with trees but may not be familiar with how to group them into angiosperms and gymnosperms. In this lab, the students will take a closer look at the different organs and tissues of each type by trying to identify them.  If your school has different types of trees, you can use them to substitute for this lab. 

  1. Students should look at their specimens and try to identify the parts of the trees and identify whether the specimen is a seed, fruit, flower, bark, cone, or any other part of the tree. 
      
  2. Instruct students to draw their specimens on the lab sheet. If you have reference material on identifying trees this would help guide the students to do a little research. The individual type of tree is identified in the module. 
  3. If you have trees in a nearby area, take the students on a walk and try to identify an angiosperm (with flowers or seeds) versus a gymnosperms (with cones).  
  4. Draw a tree similar to the one below, that shows a tree branching into gymnosperms and angiosperms.  Then show the different types. 

     

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