Life Cycle - Plants (5A)
Pre Lab 

   
OBJECTIVES:
  • Analyzing the structure of plant cells.
  • Comparing plant and animal tissues.

VOCABULARY:

  • cell wall
  • chloroplast
  • phloem
  • photosynthesis
  • vacuole
  • xylem
MATERIALS:
  • worksheets
  • crayons

Students use worksheets to examine the structure of cells.

BACKGROUND:

A plant cell is different from an animal cell in that it possesses a cell wall, chloroplasts, large vacuoles, and starch grains (amyloplasts). The cell wall is the outer wall that surrounds plant cells. Chloroplasts contain chlorophyll and function during photosynthesis. Vacuoles store food molecules, water and salts. Starch grains are used to store starch which will provide food for the plant. Plants are made up of many cells that work together to form tissues. There are many types of plant tissues.

The growth of plants occurs in the meristematic tissues. In these tissues the cells are actively dividing, and new cells are continually being produced. Apical meristems are located in roots and stems. Vascular cambium is a meristematic tissue located between the bark and wood (or phloem and xylem). Different types of plants have different types of tissues. Leaf tissue has an upper and lower epidermis which forms a relatively waterproof layer because the cuticle protects the inner cells. Cutin, a fatty material, is secreted by the epidermal cells and forms a waxy layer. There are also guard cells between which are located pores called stomata that are used when the plant transpires and in photosynthesis. Between the epidermal layers is the mesophyll which is divided into the palisade layer and a mass of loosely arranged, irregularly shaped cells called the spongy layer. The vascular bundles of the leaf are enclosed in one or more layers of compactly arranged cells forming the bundle sheath. The xylem and phloem which form a way for cells to move nutrients and water up and down a plant is a complex permanent tissue. The xylem is the principal water conducting tissue in plants and the phloem is the principal food conducting tissue.

PROCEDURE:
  1. On the worksheet students are to color the stated tissue by finding the tissues on the diagrams. Discuss with students the various parts of a plant. The key part is to illustrate the many components, not to memorize them.
      
  2. Please note that these pictures are the "ideal" plant. Have students look back at Human Biology (4A) Post and Human Biology (5A) Pre so they can compare plant and human tissues. They should notice that there are few similarities between plant and animal tissue. But then, a plant and a human are quite different!

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