Pigments of Photosynthesis
Ch. 4
Florida standard and learning goal
• SC.912.L.18.7 Identify the reactants, product, and basic
functions of photosynthesis
• Learning Goal: By the end of this lesson, students will be
able to describe the process of how pigments allow plants
absorb the different wavelengths of visible light
Sunlight spectrum
Spectrum of light
Plant pigment
Why are these pigments?
Paper Chromatography Experiment
Lab safety
• Care and purposeful movement
• No horseplay
• Be precise and accurate in scientific work
• If solvent (alcohol) gets on hands, wipe off with paper
towel
• Glassware care: never touch broken glass
• Work in teams of three
Cooperative Learning Groups of 3 students
• Materials to gather:
• Glass jar
• Chromatography paper
• Solvent (alcohol)
• Ruler
• Pencils
• Spinach leaf pigment ( one group will use orchid flower pigment )
Procedure:
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Make a straight line with your ruler 2 cm from bottom of chrom. paper
Add about 1 ½ cm of alcohol to your glass jar
Apply spinach pigment heavily to the line on your chromatography paper
Carefully place paper into jar and into alcohol note: do not let the alcohol
level go above pigment
• Allow alcohol to draw up through paper and spread out pigment @ 20min
• Work on questions during this time
• Once pigment is spread and visible. Mark top of each color and measure in mm
for original pigment line. Next measure to sovent line. Record data
Rf = Distance pigment traveled
Distance solvent traveled
Data Table A:
Filter Paper
Use colored pencils to draw your observations
Before Paper
Chromatography
After Paper
Chromatography
Distance Alcohol Traveled: ___________ mm
Data Table B:
Color of Pigment
Chlorophyll a
Chlorophyll b
Carotene
Xanthophyll
Distance Traveled (mm)
Rf value
Analysis Questions: Write the question.
1. Did the leaf you tested contain different pigments? Refer
to your results to support your answer.
2. Why did the separation of pigments in the spinach
extract occur as it did? (i.e. How does paper
chromatography work?)
3. Why are leaves green even though other pigments are
present?
4. Based on what you have learned in this lab, explain why
leaves tend to change color in autumn in New England.