Non-Majors Biology
Chapter 7
Assignments
Assignment #1
Plant Pigments Lab (wet lab)
Separate Colors in a Green Leaf using Chromatography
What you need:
• leaves, small jars (baby food jars work well)
• covers for jars or aluminum foil or plastic wrap
• rubbing alcohol, paper coffee filters
• shallow pan, hot tap water, tape, pen
• plastic knife or spoon, clock or timer.
•
What you do:
1. Collect 2-3 large leaves from several different trees. Tear or chop the leaves into
very small pieces and put them into small jars labeled with the name or location
of the tree.
2. 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.
SAFETY NOTE: Isopropyl rubbing alcohol can be harmful if mishandled or
misused. Read and carefully follow all warnings on the alcohol bottle.
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.
SAFETY NOTE: Hot water above 150 F can quickly cause severe burns. Experts
recommend setting your water heater thermostat no higher than 125 F.
4. 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 cools off.
5. Cut a long thin strip of coffee filter paper for each of the jars and label it.
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.
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.
Describe your experiment and its results. Speculate how differences in the pigments in each leaf
might affect its ability to photosynthesize.
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