LABORATORY 4

                   MULTICELLULAR ORGANIZATION OF PLANTS AND ANIMALS

OBJECTIVES OF THE LABORATORY:

            1.         To examine the three basic tissue types of plants with respect to structure and function.

            2.         To examine the organization of these three tissue types in a representative plant organ.

            3.         To examine the four basic tissue types of animals with respect to structure and function.

4.                  To examine the organization of these four tissue types in a representative animal organ.

READ: Campbell, N.A. and Reece, J.B. (2005). Biology. 7th edition.  Chapter 40, pp. 820 827 (animal tissues) and Chapter 35, pp. 712-719 (plant tissues).

INTRODUCTION:

            The previous labs have focused on the metabolism and functions of individual cells.  The purpose of this laboratory is to illustrate how cells are organized to form tissues. In contrast, the focus of labs in the other half-course (1116-3) is the organism as a whole and its interactions with the environment. It is critical to examine how individual cells are organized into multicellular organisms.

            As cells differentiate, they become quite dissimilar from one another and must be integrated structurally and functionally to form coordinated units.  Multicellular organisms are not random collections of different cells performing different functions.  Rather, they possess different levels of organization:  cells --> tissues --> organs --> organ systems.  A tissue may be defined as a group of similar cells performing a common activity.  Histology is the study of tissues. An organ may be defined as a group of tissues collectively performing a specific function.  Finally, an organ system may be defined as a group of organs performing a major body function.

            The multicellularity of an organism generally results from mitosis (cell division) of a single cell, followed by differentiation and specialization of the cells.  The basic organization of plants and animals is different since plants display indeterminate growth (i.e. they continue to grow bigger and taller throughout their lives) while many animals display determinate growth (i.e. they achieve a mature size and stop growing).  In animals, some cells in the various tissues undergo cell division but only to replace dead or damaged cells.  Some mature cells (nerve tissue) are incapable of cell division.

            The differentiation of cells into tissues and their organization into organs in plants and animals will be examined in this laboratory. For study purposes, make sketches of the tissues you observe in this laboratory.  Use the blank page(s) at the end of this laboratory to make your sketches. In addition, know the specific function and location of each of the tissue types studied in this laboratory.


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