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: 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: Distance Alcohol Traveled: ___________ mm Filter Paper Use colored pencils to draw your observations Before Paper Chromatography After Paper Distance Alcohol Traveled: ___________ mm

Data Table B: Color of Pigment Distance Traveled (mm) Rf value Chlorophyll a Chlorophyll b Carotene Xanthophyll

Analysis Questions: Write the question. Did the leaf you tested contain different pigments? Refer to your results to support your answer. Why did the separation of pigments in the spinach extract occur as it did? (i.e. How does paper chromatography work?) Why are leaves green even though other pigments are present? Based on what you have learned in this lab, explain why leaves tend to change color in autumn in New England.