leaves change color in the fall?
Plants need several things to live. They take water from the
ground through their roots. They also take a gas called carbon
dioxide from the air. Plants use sunlight to turn water and
carbon dioxide into glucose. Glucose is a kind of sugar which
plants use as food for energy and as building blocks for
growing. The way plants turn water and carbon dioxide into sugar
is called photosynthesis. A chemical called chlorophyll helps
make photosynthesis happen. Chlorophyll is what gives plants
their green color. During winter, there is not enough light or
water for photosynthesis. The trees will rest, and live off the
food they stored during the summer. They stop making food so the
green chlorophyll disappears from the leaves. As the bright
green fades away, we begin to see yellow and orange colors.
Small amounts of these colors have been in the leaves all along.
We just can't see them in the summer, because the green
chlorophyll covers them up. This is the reason leaves change
color in the fall.
Since leaves do not have the materials they need to survive in
the winter and fall, their leaves die and loose the green color.
"Separate the colors of a
green leaf using chromatography"
- leaves, small jars
- covers for jars or aluminum
foil or plastic wrap
- rubbing alcohol, paper coffee
- shallow pan, hot tap water,
- plastic knife or spoon, clock
Now, Analyze the
data and come up with your own conclusion.
- Collect 2-3 large leaves all
from different trees. Cut the leaves into very small pieces
and put them into small jars labeled with the name or
location of the tree.
- Add enough rubbing alcohol to
each jar to cover the leaves. Using a plastic knife or
spoon, carefully chop and grind the leaves in the alcohol.
- Cover the jars very loosely
with lids or plastic wrap or aluminum foil. Place the jars
carefully into a shallow tray containing 1 inch of hot tap
- Keep the jars in the water for
at least a half-hour, longer if needed, until the alcohol
has become colored (the darker the better). Twirl each jar
gently about every five minutes. Replace the hot water if it
- Cut a long thin strip of
coffee filter paper for each of the jars and label it.
- Remove jars from water and
uncover. Place a strip of filter paper into each jar so that
one end is in the alcohol. Bend the other end over the top
of the jar and secure it with tape.
- The alcohol will travel up the
paper, bringing the colors with it. After 30-90 minutes (or
longer), the colors will travel different distances up the
paper as the alcohol evaporates. You should be able to see
different shades of green, and possibly some yellow, orange
or red, depending on the type of leaf.
- Remove the strips of paper,
let them dry and then tape them to a piece of plain paper.