Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Paper Chromotography Lab

  1. Dec 21, 2005 #1
    9th Grade Honors Biology Question:

    An extract of red coleus leaves is prepared in a solvent consisting of a mixture of acetone and ether. The chromatogram obtained from the extract shows green and yellow pigments but no red pigments.

    a. Why is the red pigment absent from the chromatogram?
    b. Why can the green color of chlorophyll not be seen in a red coleus leaf?
    c. How can you prepare a chromatogram that shows the separation of the red pigment?

    For question c, i think i have to turn the paper 90 degrees, but im not sure. I am having trouble with this... Please help me. Thanks in advance.
  2. jcsd
  3. Dec 22, 2005 #2
    I would have to look into it much further to truly help you with this particular problem, but I can say that usually you do not see red (or blue for that matter) when you do chromotraphy on leave pigments because those are the two colors that the pigments that carry out photosynthesis in leaves absorb the most.

    For most NORMAL (i.e. green) leaves, when you seperate chorophyll, xanthophyll, etc. using chromotagraphy, you should get a whole lot of green and yellow staring back at you because those are the colors that are not being absorbed by that particular pigment (those are the colors being reflected back to your eye from each individual pigment). Of course, you have not been given a normal plant; so from that basic idea, you are going to have to modify and interpret what the differences could be between a green and red leaf (they don't call it "honors" for nothing :wink: ).
  4. Dec 22, 2005 #3


    User Avatar
    Science Advisor
    Homework Helper

    hint, hint, R+G=Y

    http://www.glenbrook.k12.il.us/gbssci/phys/Class/light/u12l2d.html [Broken]
    Last edited by a moderator: May 2, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook