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Factors affecting the Direction of Growth of Roots, Stems, and Leaves in a Dicot Plant (page 2)

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Author: Janice VanCleave

Design Your Own Experiment

  1. Is the elongation of roots a result of apical meristem division? Place a folded paper towel on a 1-×-1-foot (30-×-30-cm) sheet of aluminum foil. Moisten the paper towel with water. Position six pinto beans in a straight line across the center of the wet paper towel. Fold the foil around the towel and close up each end of the foil. Stand the foil package in a glass. After five days, open the foil package and use a marking pen to divide the roots into three equal sections. Open the package each day for one week and measure and compare the lengths of each section. Science Fair Hint: Use photographs and drawings of the development of the roots as project displays. They would be especially useful in presenting the procedure steps and results of the experiment.
  2. Direction of Growth of Roots, Stems, and Leaves

  3. What part of a leaf expands? Use a ruler and a marking pen to draw a grid on several leaves of different bean seedlings (see Figure 11.2). Determine the average surface area of each leaf by multiplying the length by the average width. Calculate the average surface area of the leaves each day for one week. Science Fair Hint: Use a series of drawings to represent the regions of expansion on the leaves.

Get the Facts

  1. Plants grow by cell enlargement and cell division. Biology texts can give you information about these two processes. First, find out how a cell, starting with a fixed amount of protoplasm within its walls, can grow by elongation. Second, discover the steps involved in the actual division of cells by the process of mitosis.
  2. New cells in plants are produced in meristems. These tissues are located where new growth begins on roots and stems. Find out more about these special cells. How do they compare with other cells in the plant?
  3. In dicots, the growth in diameter of stems and roots is accomplished by a band of cambium (plant tissue that produces new xylem and phloem cells). Mitosis in the cambium results in the expansion of the stem or root. Find out more about the growth in diameter of stems and roots. Exactly what produces the growth rings seen in a cross-sectional slice from the trunk of a tree? If available, you could use a slice from a tree trunk in a project display. Monocots lack cambium. How do these plants increase in diameter without cambium?
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