Download Background: Procedure

Pigment Lab
Name: Luíza Isaksen
Date: 03/01/2015
Block: 4
Question: What happens to the filter paper when placed in the
beaker with alcohol and grounded leaves?
Background:
Photosynthesis begins when light is absorbed by pigments in
the cell. One technique for separating and identifying these pigments
is paper chromatography. In paper chromatography, solvent moves
up the paper carrying with it dissolved substances-in this case plant
pigments. The pigments are carried along at different rates because
they are not equally soluble in the solvent and are attracted in
different degrees to the paper.
Many green leaves contain pigment colors that are not seen
until autumn because they are hidden by chlorophyll. A few plants
have leaves that are red, yellow, or orange all year long. In this
investigation, you will use paper chromatography to determine what
differences exist in the plant pigments of various colors of leaves.
You will determine which leaves or which part of leaves contain
chlorophyll necessary to carry out photosynthesis.
Hypothesis: If i put the filter paper in the beaker with one ½ cm
deep of alcohol/pigment mixture then the pigment will show because
the pigment moves up the paper.
Materials: Isopropyl alcohol, fresh leaves, beaker, filter paper
Procedure:
1. Prepared for you is a solution in which several different leaves
2.
3.
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were ground together with alcohol to release the chlorophyll
pigment in the chloroplasts of the plant cells.
Into one beaker pour in enough of the alcohol/pigment mixture to
cover the bottom approximately ½ cm deep.
Attach your filter paper to a pencil or pen and hang the filter
paper from the top of the beaker so that the bottom of the filter
paper is submerged in the pigment solution.
Place the filter paper into the graduated cylinder. Do not disturb
the graduated cylinders for approximately 30 minutes, or until
the solvent is about 1cm from the top of the paper.
Allow the filter paper to dry, then make a sketch of the
chromatogram. Some possible colors and the pigments they
represent are: faint yellow - carotenes; yellow-xanthophyll;
bright green-chlorophyll a; yellow-green-chlorophyll b; redanthocyanin.
Mixture 1
Mixture 2
bright green-chlorophyll a
yellow-green chlorophyll b; redanthocyanin
Analysis and Conclusion:
1. How many pigments were separated in each type of leaf? The
first leaf was light green and the second leaf was purple and
dark green. The first leaf the pigment was bright greenchlorophyll a. The second leaf the pigments were yellow-green
chlorophyll b, red-anthocyanin.
2. How did the pigments in the green leaf compare with the
pigments in the red/purple leaf? They were not the same, vide
answer #1.
3. Which of these leaves can carry on photosynthesis? Explain
your answer. Both, because they have chlorophyll.
4. Which pigments work best for carrying out photosynthesis? The
pigment of mixture 1 works best for carrying out photosynthesis
because there is green pigment and mixture 1 does have some
green but mostly yellow and a shade of red.
5. Many trees have leaves that are green in the summer and red,
orange, or yellow in autumn. Where were these colors during
the summer? How can they suddenly appear in the autumn?
Plants also have carotenoids (yellow and orange) and
anthocyanin (red). During the summer they were hidden by the
green. Plants stop making chlorophyll the leaves loose the
green and allow other pigments to show.
I accept my hypothesis because the filter paper clearly shows
that the pigment went up the filtered paper showing that different exist
in the leaf.
Some measurement errors could have been caused by
accidently mixing two different types of leaves in the same solution.
If you didn’t wait enough time for the pigment to move up the
filtered paper maybe it would not move up in time.
Make both mixtures separate but put the filtered paper at the
same time in each mixture to see if they would have the same effect.
A real life example is: Plants also have carotenoids (yellow and
orange) and anthocyanin (red). During the summer they were hidden
by the green. Plants stop making chlorophyll the leaves loose the
green and allow other pigments to show