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TRANSCRIPT
Leaves and Light
Research Question
The question that I researched and experimented on is if color affects photosynthesis. In
this question, I am also researching if leaves absorb different wavelengths of light differently and
what happens if there is no light at all. I chose this question because we have plants all over the
world and they are one of the most important parts of the existence of other life. We use them for
food, water, shelter, medicine, oxygen, and more. The way that plants thrive is by using
photosynthesis. I wanted to explore this question to possibly find a way that plants can grow
quicker and better with one color, than another. My conclusion could lead to a more efficient
way of planting.
Background Information
According to Encyclopydia Britannica, photosynthesis is the process that green plants
and certain other organisms transform light energy into chemical energy. Photosynthesis is very
important in the maintenance of life on Earth. Photosynthesis is the process of converting light
energy to chemical energy in plants, and they store the energy in the form of bonds of sugar. This
process utilizes light energy from the sun, carbon dioxide, glucose, and water to make sugar and
the leftovers of that process is oxygen that is given off into the air that we breath. Chlorophyll
captures energy from the sun by absorbing rays of light that travel in waves. There are two types
of chlorophyll, chlorophyll a and chlorophyll b, that absorb different wavelengths of light and
they work together to give the plant all of the energy it needs to make food. The formula how
those things together goes through a chemical change into new substances is 6CO2 + 6H2O (+
light energy) → C6H12O6 + 6O2. The process of photosynthesis takes place in the chloroplasts,
which are the food producers of the cell, using chlorophyll. Chlorophyll is the green pigment that
makes the plant’s green color and growth. Within the cell a type of chlorophyll, organelle,
captures the light from the Sun. The molecules are stored and converted in the part of the plant
called the stroma. Chlorophyll is always being created as long as there's light. Chlorophyll a
(alpha) absorbs light at a wavelength between 453 to 642 nanometers (a billionth of a meter),
which are the blue and red portion of the electromagnetic spectrum. Chlorophyll b (beta) absorbs
wavelengths at 460 to 647 nm, which are blue. They both reflect green and greenish
wavelengths. The mitochondria works in the opposite way by using cellular respiration, which is
breaking down the sugars and nutrients that the plant uses.
Plants are important because they give us so much that we need to survive. Things like
the food that we eat comes directly or indirectly from plants. They are the first organisms on the
food chain, which means that they only need the sun for food and animals use the plants as food.
They give us oxygen from the process of photosynthesis. We also use plants as medicine.
Onequarter of all prescription drugs come from plants and four out of five people around the
world use plants as their primary medication. Finally, come humans and other animals use plants
as their shelter.
If the plant doesn’t have any light it will gradually start dying because it uses the light to
create food. Without food the plant will turn brown, white, or yellow, due to the lack of
chlorophyll, and it will not grow. It may even develop a condition known as chlorosis, which is
the yellowing of plant tissues due to malnutrition in the plant. If one color of light is missing then
it may change the production of photosynthesis because the plant may need one wavelength of
light more than another to grow properly. Some colors may be necessary for a plant, others can
be used, but unnecessary, and other are not absorbed by the plant at all.
In the Encyclopedia Britannica it states that light, electromagnetic radiation that can be
detected by the human eye. Electromagnetic radiation occurs over an extremely wide range of
wavelengths, from gamma rays. Light is an electromagnetic wave, which are similar sound
waves because they have different frequencies. The different colors have different frequencies,
as sound has different frequency for each sound. Wavelength is a measure of the cycles of the
wave of light. Light comes in different wavelengths, which to us look like different colors of the
rainbow because each color of light has it's own unique wavelength. The reason we see a
rainbow of different colors is because each color’s unique wavelengths are separated from the
others when they travel through water or air. This creates a rainbow of different colors. The light
in the experiment is Monochromatic light because most light you see is multichromatic. It is
made up of one single pure frequency and the light looks to the eye as a pure color. When you
see a colored object, it absorbs every color of light except the one it appears to be. Sunlight has
all the colors in the rainbow, then the leaves absorb them, and they use it to produce chlorophyll.
Chlorophyll looks green because the leaf absorbs red and blue light, which makes those colors
imperceptible to the naked eye. It is the green light which is not absorbed reflects off the leaf and
is visible and makes chlorophyll appear green.
In a study by Dr. Srinivasan, called the Intro to Cell Biology, there were beakers with
Spinacia Oleracea exposed to different color lights. In the end he found that the green light
worked the slowest because the plant do not absorb the light. The normal light was the most
successful because it gave the plant all the colors to be absorbed.
Ocimum basilicum (basil) is a culinary herb of the Lamiaceae (mint) family. Basil is
originally native to India, having been cultivated there for more than 5,000 years, but it is best
known as an important aspect of Italian cuisine, and it also a part of cuisine in Southeast Asian.
Places like Cambodia, Indonesia, Laos, Thailand, Vietnam, and Taiwan. The leaves has a taste
and aroma similar to anise, with a pungent, sweet smell. Basil grows between 30–130
centimeters (12–51 in) tall, with light green leaves and there are small, white flowers.
Basil needs 6 to 8 hours of sun and should not be left in direct sunlight in the afternoon
when the sun is the strongest. Set out plants at least 2 weeks after the last frost in spring or in the
summertime because the plants are very frost sensitive. Basil grows best in nutritious, moist, yet
welldrained soil with a pH of 6 to 7.
Hypothesis
My hypothesis is that the color does affect photosynthesis. I think that the green light will
be the second least efficient because green is the color that the plant doesn’t absorb. I believe that
the red and blue will perform better because those are the main color that are taken in by the
plant for photosynthesis. However, I think that the unaltered sunlight will do the best because it
has both the blue and the read and all the other colors, which are still taken in by the plant. The
plant with no sunlight will do the worst because it is missing a crucial part of photosynthesis, so
it will die or grow extremely slowly.
Variables
In my project the plant with the clear cover is the positive control and the plant with the
black construction paper is the negative control. The colors of light that the plant gets are the
independent variables. The growth of the plant, the color, production of chlorophyll, and
appearance is the dependent variable. Then controlled variables will be the location, temperature,
amount of water, sunlight, and soil.
Materials List
1. 30 clear transparency film
2. permanent markers: red, green, blue, yellow
3. 3 black construction paper
4. clear liquid glue
5. 18 three inch tall sweet basil plants
6. a sunny window
7. 252 tablespoons (3.73 liters or 15.75 cups) of water
8. soil
9. 18 plant pots
10. Ruler
11. Observation table
Color Plant #1 Plant #2 Plant #3
Clear
Blue
Green
Yellow
Red
Black
Procedure 1. Get 18 small basil plants.
2. Put them in pots with ten cups soil.
3. Take one transparent film and make roll it into a cylinder so the two edges just meet with
the top and bottom open and glue it closed.
4. Then take another sheet and cut it into one circle the same size as an opened end of the
cylinder. Then glue that to one of the opened ends of the cylinder. (you may need to use a
paintbrush to spread the glue around)
Option 1
5. Do steps 3 and 4 three times with clear transparency film.
6. Do steps 3 and 4 three times with black construction paper
7. Use your permanent markers, color six sheet of transparency film completely with each
color. When you are done, you should have six red sheet, six yellow sheet, six green
sheet, and six blue sheet. Do steps 3 and 4 with all the sheets.
Option 2
8. Take printable transparency paper and print using the instructions of the box. Use this
link:
https://docs.google.com/document/d/1PqTjMLtmBH_KsmqCS5d7TTs8F_vumYj64gA0r
8rHaOs/edit#
9. Do steps 3 and 4
10. Cover three basil plants with each of the colored cylinders.
11. If there is wind use tape or weight to keep it from knocking off.
12. Put all the plants in the sun in the same area for two weeks.
13. Put a third of a cup of water directly into the soil everyday at 3 in the afternoon making
sure that all the soil is moist.
14. Every half week write observations on each individual plant in a chart about the color of
the leaves and the growth (measure from the soil to the highest point of the plant). You
may also take pictures to have a visual comparison. (Use table above)
15. From the research find which color of light was best for growing the plant.
Color Day 1 Day 4 Day 7 Day 10
Clear
(Full light)
(All
colors)
Dark green
Strong thick leaves
Three inches tall
Dark green
Strong thick leaves
Three and a half
inches tall and more
leaves
Dark green
strong leaves
4 inches tall
abundance of
leaves
Many leaves
Strong and dark
7 inches tall
Blue Dark green
Strong thick leaves
Three inches tall
Dark green with a few
spots of brown
Strong thick leaves
Three inches tall
Dark green with a
few spots of brown
Strong thick leaves
Three inches tall
Dark green with a
few spots of brown
Not many leaves
Six inches tall
Green Dark green
Strong thick leaves
Three inches tall
Dark green leaves with
slight brown spots
Thinner, weaker leaves
Three inches tall
Lighter green leaves
with slight brown
spots
Thinner, weaker
leaves
Two inches tall
More leaves
Lighter green leaves
with slight brown
spots
Thinner, weaker
leaves
one inches tall
Yellow Dark green
Strong thick leaves
Three inches tall
Dark green with few
spots of brown
More sprouts growing
Starting to weaken
Three inches tall
Dark green with few
spots of brown
More sprouts
growing
Starting to weaken
Dark green with few
spots of brown
Starting to weaken
Three inches tall
Not growing
Three inches tall
Red Dark green
Strong thick leaves
Three inches tall
Dark green
Strong thick leaves
Three inches tall
Dark green small
spots of brown
Strong thick leaves
Four inches tall
Dark green slight
spots of brown
Strong thick leaves
Four inches tall
Black
(No Light)
(Negative
Control)
Dark green
Strong thick leaves
Three inches tall
Some leaves have
fallen
Brown fragile leaves
Two inches
Shriveling
Leaves have fallen
Brown fragile leaves
One inches
Shriveling, but the
stem is still there.
Completely dead
No plant
Brown stems
Zero inches tall
Graph 1 and 2
Conclusion In conclusion, my hypothesis was correct. The clear (positive control) did the best
because it
grew a lot and the leaves are strong and green. The red and blue also did well, but the red did
better than the blue, which could be because the blue is darker so the light couldn’t get through
as well. Both plants did not grow much in the beginning, but they stayed alive and healthy. The
green and yellow did not do as well. The green slowly died and the yellow stayed the same
height, but it’s leaves got weaker and started to shrivel. The black died very quickly and
shriveled completely in the end. This means that the red is similar in closeness with all colors of
light, which means it is the most important in the plants growth.
Further Discussion
I think that my experiment could be changed in the future if I use a different shade of
colors and there is the same amount of space, same amount of air, and more, so they are all in the
exact same environment. Using my conclusion farmers and other planters can use a more red
color of light to grow plants sense the result of growing plants with just red light is similar to all
colors. My research can be used for further investigation to see why the red light was most
important to the plant production of photosynthesis and if the shade of color also varies the
result.
Bibliography
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<http://webcache.googleusercontent.com/search?q=cache:nfFnflRSOvsJ:users.rowan.edu/~worthm79/theeffectsofdifferentlightcolorsonphotosyntheticrateinspinaciaoleracea.docx &cd=6&hl=en&ct=clnk&gl=us>.