Life Cycle - Plants (5B)
Lab 

   
OBJECTIVES:
  • Comparing reproduction in a gymnosperm and angiosperm.
  • Determining male and female plant parts.
VOCABULARY:
  • angiosperm
  • cone
  • gymnosperm
  • pollen
  • pollination
  • seed
  • sexual
MATERIALS:

Students compare the reproductive organs of different plants

BACKGROUND:

Gymnosperms are the non-flowering seed plants such as cedar, pine, redwood, hemlock, and firs. Gymnosperms are woody plants that bear "naked seeds." They are called naked because their seeds develop exposed on the upper surfaces of cone scales, such as in pine cones. A pollen grain is carried by wind currents to the appropriate "egg" where the growth of the pollen tubes through this tissue brings the sperm to the egg. Gymnosperms are usually of large size with much secondary growth, the leaves are usually evergreen needles or scales.

Angiosperms have flowers and bear seeds enclosed in a protective covering called a fruit. Angiosperms are the dominant types of plants today. Angiosperms are further divided into monocots and dicots. Monocots have one seed leaf. Dicots have two seed leafs. There are at least 250,000 species of angiosperms ranging from small flowers to enormous wood trees. Pollination is accomplished by wind, insects, and other animals. The male part is the pollen grain, and the female part is the ovary. The ovary goes through meiosis to produce an "egg", which is them fertilized by the "sperm" carried by the pollen. The sperm of the male part travels down the pollen tube in the style. Two sperm enter the micropyle of the ovary. After the process of mitosis, it turns into a seed with an embryo. The seed may be inside a fruit.

PROCEDURE:
  1. Discuss how angiosperms and gymnosperms reproduce. You may want to review the different parts of the plants.
      
  2. In angiosperms, the pistil is the female reproductive structure found in flowers, and consists of the stigma, style, and ovary. There are two parts to an angiosperm: a male part and a female part. The male gametophyte consists of 2 or 3 cells contained within a pollen grain; the female gametophyte consists of eight cells contained within an ovule. The stamen is the male reproductive structure of a flower; usually consisting of slender, thread-like filaments topped by anthers, which contain the pollen.

     

  3. In gymnosperms the cone is the female reproductive part and the pollen is the male reproductive part. Pine trees and other gymnosperms produce two types of cones. The male cone is called the pollen cone. The larger female cone is the seed cone. A single tree usually produces both pollen and seed cones. Spore-producing structures are found on the scales of cones.
      
  4. Give students the bags of materials.  You should have the students keep the material inside the bag and use a hand lens or microscope to look at the materia

    You may ask student so bring in a flower, seed, or pine cone.  This would be excellent to dissect in the lab.

    You have the following materials in your kit (some materials may change):

    Alder (angiosperm) this is cone like structure, but its seeds are not naked, it gives the appearance of a gymnosperm, but this is one of the exceptions that all cones are gymnosperm

    Liquidambar (angiosperm)  - this is a fruit husk, the seed would be inside; the fruit is green

    Pine (1) gymnosperm, if you see a slight yellow color these are pollen grains, you need a microscope to look at them

    Pine (2) -  gymnosperm, pollen can be seen with a microscope

    Pine (3)  -  gymnosperm,  cone is female part

    Baby’s Breath angiosperm, flower Lavender angiosperm, flower
    Sage
    angiosperm, the seeds would be inside the fruit husk

    Corn angiosperm, monocot,  seed

    Bean angiosperm, dicot, seed

 



 

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