Plants Toward Sun Essay, Research Paper

Have you ever wondered why your plants in your house and outside lean towards the sun. In my project I hope to answer why this happens. I am going to be using lima beans to do this with. The Greek philosopher Aristotle may have been the first to attempt to explain the processes of photosynthesis and food production. He believed that plants could obtain from the soil all the components required for growth. The cycle was completed when organisms perished and became reincorporated into the soil.

This view was not seriously challenged until the 17th century with the experiments of Joannes Baptista van Helmont, a Flemish physician. He carefully measured the weight increase of a willow planted in soil, to which he periodically added only rainwater. The plant increased in weight by 77 kg (169 lb), and the soil decreased in weight by 57 gm (2 oz). He concluded that it was water, and not substances in the soil, that provided plants with their growth material. Later, in the early 18th century, Stephen Hales conjectured that light and air might be significant factors in the growth of plants.

The classical experiments of Joseph Priestley laid the foundations of the modern photosynthetic theory. He found that the composition of air inside a closed glass container changed after a candle had burned in it or after a small animal had breathed in it. This air then was unable to support further burning or breathing. He proposed that this “fixed air” contained “phlogistic matter”?later found to be carbon dioxide?that could be “dephlogisticated” by plants. Although his interpretation was wrong, he had discovered that plants use a component of the atmosphere in their life processes.

Jan Ingen-Housz in 1779 and Jean Senebier in 1796 refined Priestley’s ideas. They observed that plants could restore the “fixed air” only in the presence of light; the plants made the air noxious if kept in darkness. The role of light in photosynthesis thus was firmly established. Antoine Laurent Lavoisier had previously described the chemical composition of air; his findings led Ingen-Housz to recognize that plants utilize carbon dioxide to obtain carbon in order to build organic molecules and that they release oxygen into the atmosphere. That plants need water in the process was demonstrated by careful quantitative experiments of Nicolas Th odore de Saussure. With the formulation of the theory of energy conservation in 1845 by Julius Robert Mayer, the function of light as the energy source for the photosynthetic process began to be understood, and the basic elements of the photosynthesis were established.

George G. Stokes and Henry C. Sorby first described the chemical structure of the green, light-absorbing pigment chlorophyll. By 1913, Richard Willstatter and A. Stoll had published the empirical formulas of the two major forms, chlorophylls a and b. They hypothesized that the chlorophyll itself combined with carbon dioxide and water and that light decomposed the complex into oxygen and formaldehyde. This theory was superseded in the 1920s, when Otto H. Warburg and Warbus Negelein demonstrated that the photosynthetic machinery consists of several distinct parts, and a variety of different molecules are involved in the photosynthetic reactions. In 1937, Robert Hill showed that isolated chloroplasts could produce oxygen in the presence of chemicals that could accept electrons. As a result he established the idea of a light-activated chain of components that cause the flow of electrons from water to other acceptors with the resultant release of oxygen and the formation of chemicals needed to form organic compounds from carbon dioxide and water.

Photosynthesis is the biological process by which the energy of sunlight is used in the formation of organic compounds and in the release of oxygen from carbon dioxide and water. Although primarily associated with green plants, photosynthesis also occurs in algae and a variety of bacteria and can be quite diverse in its nature. The common factor in all variations of photosynthesis is the absorption of light energy to provide an energy source for the needs of the organism. This process ultimately supplies the energy required by all living organisms for their continued survival.

Materials:

Lima Beans, planting soil, two shoe boxes, cup

First I will put the Lima beans into the soil which will be in the cup. Then I will cut out a maze in the shoe box and put a hole in the top of the box at one end. Then place the plant at the opposite end of the box. I will then put a plant into another shoe box with no hole in it and compare the results.

My hypothesis is that the plant will grow towards the light and the plant that is in the box with no light will die.