EXERCISE B: 6.What is the purpose of starch in plants? 7. What would the levels of starch have looked like in the leaf if the plant had been kept in the dark for several days before the experiment? EXERCISE C: 8. What is the name of the main (green) pigment in plants? 9. What is the function of accessory pigments in plants? 10. Which of the 4 pigments in spinach is the most hydrophobic (and travels fastest up the chromatography paper with the hydrophobic solvent)?.