Download Background Research All living things need energy. Animals get

Background Research
All living things need energy. Animals get their energy and the materials they need to grow
their bodies through the food they eat, which generally includes plants. Plants grow using carbon
dioxide from the air and water and a few minerals from the soil. They do this with the aid of
sunlight, in a process called photosynthesis, which means "putting together with light." Plants
use pigments in their leaves that absorb sunlight to carry out photosynthesis. The most important
pigment is chlorophyll (Botanist, 2003).
Sunlight is actually different "wavelengths" of different colors of light. Chlorophyll
absorbs blue and red light. The wavelengths of light that are not absorbed are reflected--as green.
The energy absorbed from the sunlight dislodges electrons – which are parts of atoms - from the
pigment molecules. The electrons then organize within the leaf cells into tiny electric currents.
This is the energy that powers a series of very complicated chemical reactions. These reactions
result in the formation of a sugar called glucose that is stored in the form of another sugar called
cellulose, and which the plant can use for energy and for the structure of the plant (Botanist,
2003).
However, even plants cannot live on air and sunlight alone. Even though they do not take
nutrient fluid out of the soil, they do need some nutrients contained in soil (Guy and Gal, 1999),
which they get through their roots (see Figure 1). The main one is nitrogen. Nitrogen is necessary
for making protein and nucleic acids. Nucleic acids are the main ingredient of DNA, the material
that holds genetic information in every cell (Guy and Gal, 1999).
Figure 1: The parts of a plant. Light
hits the leaves and is converted into
energy for the plant with help from
the pigment chlorophyll. Carbon
dioxide is taken up by the leaves and
converted to oxygen. Plants also get
nutrients and water from the soil
through their roots.
Plants also need other nutrients from soil including phosphorus, potassium, sulfur, calcium,
iron and magnesium, and a list of "micronutrients": molybdenum, copper, zinc, manganese,
boron, chlorine and nickel. And probably others in amounts too small for us to detect (Guy and
Gal, 1999).
We noticed that groups of plants growing in our front yard were not growing very well
while groups of similar plants that were growing in our backyard were doing just fine. Since
both sets of plants were getting plenty of sunlight, air and water, we wanted to test the possibility
that something was wrong with the front yard soil.
One type of plant growing in our yard is the daisy. Daisies are flowering plants and belong
to the family known as Asteraceae. Daisies are native to north and central Europe but grow just
Figure 2: Picture of an English daisy flower. This is
the type of daisy that grows in our yard and the
flower that we will test in our experiments.
about everywhere. English Daisy is a serious weed in the northwest United States and that is the
type that is growing in our yard (see Figure 2). Daisies are commonly grown from seed.
Daisies can be directly seeded into a flowerbed. Just before the blooming, daisies need a
soil that is high in phosphorous as it helps to promote big, bright blooms (Dent et al., 2001). This
makes daisies ideal for testing the effects of soil on their growth. We therefore decided to test
how the soil from our yards affects daisy growth.
Bibliography
Botanist, I. M. A. (2003). Plants and everything you wanted to know about them. Shyster and
Co., New York. pp. 123-130.
Guy, S. M. and Gal, J.L. (1999). Dirt: what’s in it and why do plants like it so much? J. Plant
Science. 44:233-277.
Dent, S. T., Otto, D.S., Dude, F.P. (2001). The wonderful life of a daisy. Flowerchild Publishing
Co., Seattle. pp. 1-7.