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Angelica Wright Robert Fulton
5300 S. Hermitage
Chicago IL 60609
To define the term photosynthesis.
To practice iodine test for the presence of starch in leaves.
To compare the results of iodine test of two leaves one that has been exposed to
sunlight and one that has not.
CAUTION! This activity uses heat and requires safety training and supervision!
small dish iodine eye dropper plant sauce pan alcohol
beaker tweezers black plastic tape scissors
1. Tape plastic around some of the leaves of a geranium plant. Place the plant
in a light place for two days. Then pick a wrapped leaf, and one is not
2. Heat water in a sauce pan, warm alcohol in a beaker. Dip both leaves in hot
water and then leave them in the alcohol. When the leaves are almost white, add
iodine to them.
The leaf that was not wrapped turns a dark color, but the leaf that was wrapped
remains the same. The fact that the wrapped leaf did not change color shows
that it did not have any starch. The change in color in the unwrapped leaf
indicates the presence of starch. The difference between the leaves is the
exposure to sunlight. It goes to show that sunlight is necessary for the
manufacture of plant food. This process in which plants use sunlight and other
natural resources to make their food is called photosynthesis. The green color
or pigment is called chlorophyll. The light is absorbed by the chlorophyll
which also transfers the energy thus derived and in some brings about the
Part B-Water Transport
To show hands-on how water is transported through the stem to other parts of the
glasses food coloring fresh carnations or celery with leaves
Pour five to seven drops of food coloring to each glass then add some water to
each glass. Trim the flowers or celery stem so that the tubes will be freshly
open and not clogged. Split the stem of one of the flowers. Put the split stem
goes into each of the two glasses that hold two different colors. Put the
unsplit flower into one of the glasses with colored water. Leave flowers at
room temperature for an hour so.
The flowers will slowly and gradually change color. The flowers in each glass
change to the color of the food coloring in the glass. The flower with the
split stem will change into two different colors, one each side of the flower.
This process shows that the stem of a plant not only holds the plant or tree in
an upright position, but it also helps in the transportation of foods and
liquids from one part of the plant to other.
Findings can be judged by the science journal entries, or by oral or written
reports. These activities are PASS/FAIL only.