Photosynthetic Pigments

Question 1

What method is best used in this lab?

Answer 1

Paper chromatography

Question 2

Why is paper chromatography being used?

Answer 2

To observe them individually and learn more about each one

Question 3

What is an Rf value ?

Answer 3

Reflects how far the pigment moved from its origin, relative to how far he solvent front moved

Question 4

How do you calculate Rf value?

Answer 4

Measure the distance the pigment so it travelled - origin to center of final pigment location then divide this by the distance from the origin to where your solvent front stopped

Question 5

Explain how to extract pigments from a plant sample using heat and ethanol

Answer 5

Cut 2-3 large leaves, into small pieces.
Add 4ml of ethanol, let boil down to 1ml (deep green colour)
Pour extract into a plastic vial

Question 6

Explain each step of paper chromatography

Answer 6

• Apply extracted pigments to the dot at high concentrations by doing repeatedly dotting - leave to dry before adding another drop (8-10 times)
• hang the filter paper do the glass hook, don’t touch it w the solvent
• let the tube and filter paper saturate with solvent vapours
• slowly immerse the tip in the filter paper into the solvent, don’t let it touch the dot
• take the paper out when it reaches the 10cm line

Question 7

Draw an absorption spectrum

Answer 7

Look online or lab book

Question 8

Which colour(s) of light would you shine on a plant to help it grow as efficiently as possible?

Answer 8

Red/violet - absorbs light + wavelengths

Question 9

If you wanted to grow a plant as slowly as possible, what colour(s) of light would you shine on it ?

Answer 9

Green - reflects all the light; photosynthesis cannot occur