Download Do Plants Need Sun?

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Discoveries from U.S. soybean
farmers and their checkoff.
3. 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 water.
4. Keep the jars in the water for at least a half-hour, longer if needed, until the alcohol has become
Discoveries from U.S. soybean
colored (the darker the better). Twirl each jar gently about every five
minutes.
farmers
and their Replace
checkoff. the hot
water if it cools off.
5. Cut a long thin strip of coffee filter paper for each of the jars and label it.
GRADES
6. 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.
7. 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.
Living Systems
Do Plants Need Sun?
8. Remove the strips of paper, let them dry and then tape them to a piece of plain paper. Compare
lesson in
what
plants
andmuch less color in the stressed
theAstressed
leaves
to soybean
the healthy
leaves.need
Thereto
is grow
normally
leaves
compared
withfood
the green
chlorophyll of the healthy leaves.
make
their own
and energy.
What’What’
s Going
s theOn?
Word?
Leaveschlorphyll
are nature’s food factories. Plants use sunlight to turn water and carbon dioxide into
glucose.
Plants
What
You use
Needglucose as food for energy and as a building block for growing. The process is
calledSoybean
photosynthesis,
which means
“putting together with light.” A chemical called chlorophyll
plant with healthy
green leaves
helps Paper
make clips
photosynthesis happen. Chlorophyll is what gives plants their green color. When there
construction
paper for photosynthesis, like during fall and winter, the plants will begin to
is notBlack
enough
light or water
shut down
their
food-making
factories. The green chlorophyll disappears from the leaves. As the
What to Do
green Cut
fades
away,
we
begin
to
see a paper
yellowfour
color. This color has been in the leaves all along. We just
out of the black construction
can’t see
it in
because
is covered
square
or the
oval summer,
pieces. Cover
up two it
leaves
on the up by the green chlorophyll.
healthy green plant with the black construction
paper pieces, one on top of the leaf and one piece
on the bottom of the leaf. You can use paper clips to hold the paper onto the leaves.
Look at your leaves to make sure that the entire leaf area on top and on the bottom is covered up
and won’t be able to get any sunlight.
Put the plants on a shelf or table where they get plenty of sunlight.
After a week, remove the paper clips and pieces of black construction paper. What do the leaves
look like? What color are they? What do you think happened?
Leave the plants on the windowsill or tabletop for another week. Water the plants when needed.
Watch the leaves and see what happens to them when they are able to get sunlight again. What
causes them to turn green again?
Discussion
Do plants need sunlight?
What happens if plants do not get sunlight?
Discuss the experiment, and what you observed, and draw conclusions on what you think happened
to leaves when they were covered up and then uncovered. Use terms like sunlight, energy, chlorophyll,
and experiment.
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Adapted from materials developed by the United Soybean Board