Distribution Of Growth
A Lab Experiment Growth in plants refers directly to an increase in size and weight. Often it is thought of as a process, but it is more accurately described as a system of subprocesses. (Meyer, 409) Growth is not equally distributed throughout a plant, rather there are only certain areas in the plant that will do the growing. (Distribution of Growth packet) These areas are called meristems. These meristems allow for cell division and enlargement. (Meyer, 409) When conditions are favorable for the meristem, new cells will be produced as a result of repeated mitosis. These meristems are actually tissues, capable of growth throughout the entire life of the plant. This is known as the plant's primary growth. (Software Toolwork's Encyclopedia) As stated before, growth only occurs in the meristems of a plant. This means that only a certain part of a root, stem, and leaf containing a meristem will grow. In most cases, only the tip of a root grows. This is called the root-apical meristem, which is responsible for developing an extensive root system required for continued growth of the plant. (Software Toolwork's Encyclopedia) The growth of the stem is credited to the cambium, its meristem. Aside from allowing the stem to grow thicker and taller, the cambium also maintains the xylem and phloem. Producing these other areas of tissue in a plant is called secondary growth. (Meyer, 419) The cells inside a leaf are usually arranged in two layers. There is an upper layer that is made up of large palisade cells, and the lower is made up of spongy tissues. There are many other factors that also affect a plant's growth. Some of these factors include the climate, ph of rainfall, gases, and competition with other plants. (Fuller, 238) Any one of these factors can greatly contribute to a plants growth, both negatively and positively. Methods and Materials To begin this lab, bean plants had to be grown. Although only six plants had to be grown, this soon became a troublesome task. After realizing the plants would not sprout in time, we decided to stamp several leaves from the plants grown in the environmental class. We stamped these leaves with the
ink, this divided each leaf into equal areas. The length and width of each leaf was recorded, along with the measurements of each of the regions made by the stamp. These measurements were taken every three days over a twelve day period. Next on our list was the root. Six seeds were placed in a petri dish with wet paper towels. After the roots sprouted, they needed to be marked with India ink, too. This was a very tedious task because of the small size of the roots. After the initial marking, two days had passed and new results were recorded. After this, averages were figured out for the length of the first two lines on each seed. Finally came the stem. Six plants were grown, and marked with the India ink. Ten marks each 2mm apart were made. Like the roots, they were checked two days later and then averages were drawn up. Results: Leaves: The leaves were measured by their length, width, and distance between the lines made by the India ink. On the first day, we recorded: Length Width Distance Leaf #1 5.1cm 3.0cm .5cm Leaf#2 4.5cm 2.5cm .5cm Leaf#3 5.4cm 2.8cm .5cm Leaf#4 6.1cm 2.9cm .5cm The third day: Length Width Distance Leaf #1 5.1cm 3.1cm .5cm Leaf#2 4.5cm 2.6cm .5cm Leaf#3 5.5cm 2.9cm .5cm Leaf#4 6.1cm 2.9cm .5cm The sixth day: Length Width Distance Leaf #1 5.2cm 3.1cm .5cm Leaf#2 4.5cm 2.7cm .6cm Leaf#3 5.7cm 3.0cm .6cm Leaf#4 6.2cm 3.0cm .6cm The ninth day: Length Width Distance Leaf #1 5.3cm 3.2cm .5cm Leaf#2 4.6cm 2.8cm .6cm Leaf#3 5.8cm 3.1cm .7cm Leaf#4 6.2cm 3.1cm .6cm The last day (12) : Length Width Distance Leaf #1 5.3cm 3.3cm .5cm Leaf#2 4.7cm 2.9cm .6cm Leaf#3 6.0cm 3.1cm .7cm Leaf#4 6.3cm 3.1cm .6cm Roots: An average was taken for the first two lines of the roots, each segment after that was measured individually. Our results are as follows: Root#1 Segment Measurement 1+2 avg. .4cm 3 .2cm 4 .2cm 5 .2cm 6 .1cm 7 .1cm 8 .1cm 9 .1cm 10 .1cm Root#2 Segment Measurement 1+2 avg. .5cm 3 .2cm 4 .2cm 5 .2cm 6 .1cm 7 .1cm 8 .1cm 9 .1cm 10 .1cm Root#3 Segment Measurement 1+2 avg. .3cm 3 .2cm 4 .1cm 5 .1cm 6 .1cm 7 .1cm 8 .1cm 9 .1cm 10 .1cm Root#4 Segment Measurement 1+2 avg. .3cm 3 .2cm 4 .2cm 5 .1cm 6 .1cm 7 .1cm 8 .1cm 9 .1cm 10 .1cm Root#5 Segment Measurement 1+2 avg. .4cm 3 .2cm 4 .2cm 5 .1cm 6 .1cm 7 .1cm 8 .1cm 9 .1cm 10 .1cm Root#6 Segment Measurement 1+2 avg. .4cm 3 .2cm 4 .2cm 5 .2cm 6 .1cm 7 .1cm 8 .1cm 9 .1cm 10 .1cm Stems: An average was taken for the first two lines of the stems, each segment after that was measured individually, just as the roots were done. Our results are as follows: Stem#1 Segment Measurement 1+2 avg. .7cm 3 .4cm 4 .3cm 5 .2cm 6 .2cm 7 .2cm 8 .2cm 9 .2cm 10 .2cm Stem#2 Segment Measurement 1+2 avg. .8cm 3 .5cm 4 .3cm 5 .3cm 6 .2cm 7 .2cm 8 .2cm 9 .2cm 10 .2cm Stem#3 Segment Measurement 1+2 avg. .7cm 3 .5cm 4 .5cm 5 .3cm 6 .2cm 7 .2cm 8 .2cm 9 .2cm 10 .2cm Stem#4 Segment Measurement 1+2 avg. .6cm 3 .3cm 4 .3cm 5 .2cm 6 .2cm 7 .2cm 8 .2cm 9 .2cm 10 .2cm Stem#5 Segment Measurement 1+2 avg. .9cm 3 .7cm 4 .4cm 5 .3cm 6 .2cm 7 .2cm 8 .2cm 9 .2cm 10 .2cm Stem#6 Segment Measurement 1+2 avg. .7cm 3 .4cm 4 .4cm 5 .3cm 6 .3cm 7 .2cm 8 .2cm 9 .2cm 10 .2cm Discussion: The growth of the leaves was about what we had expected it to be. It was tough to get the plants to grow, probably due to the cold draft from the window. This began to slow us down and we ran short on time. The plants that were grown from the environmental classes had to be used. Before Christmas vacation, seeds were placed in petri dishes with wet paper towels. By the time we came back we could tell that the seeds had sprouted, but had died from lack of water. It was determined that we would quickly have to perform this experiment at Mr. Kihm's private laboratory. After these measurements were taken we could see that we had guessed right in that the most growth would occur at the tip of the roots. For the stem measurements we had to grow our own again at Kihm's Science Museum. It came to be determined that the average measurement for the stems was 2.83cm. The stem results were on target with what we expected. Conclusion: Right from the very beginning of this lab we were plagued with problems. From plants not growing at all, to ones that did but died. From our readings, we were able to determine that most growth would take place in the roots, leaves, and stems. The most notable facts that we learned were that plants do not mature like animals do, they are continually growing, and that only certain parts of these plants do the growing. Bibliography: Foresman, Scott. Biology. Oakland, New Jersey: Scott Foresman and Company, 1988. Franck, Irene, and David Brownstone. The Green Encyclopedia. : Prentice Hall General Reference, 1992. Fuller, Harry J., and Zane B. Carothers. The Plant World. New York: Holt, Rinehart and Winston, Inc. 1963. McLaren, Rotundo. Heath Biology. New York: Heath Publishing, 1987. Meyer, Bernard S., and others. Introduction to Plant Physiology. New York: D. Van Nostrand Company, 1973. The Software Toolwork's Multimedia Encyclopedia. New York: Grolier, Inc., 1997.