Q.6:- Why is the colour of a leaf kept in the dark frequently yellow, or pale green? Which pigment do you think is more stable?
Carotenoid pigments are found in all photosynthetic cells. They are accessory pigments also found in roots, petals etc. These pigments do not breakdown easily thus temporarily reveal their colour due to unmasking, following breakdown of chlorophylls. Thus the colour of leaf kept in dark is yellow or pale green.