Question

3.    In the fall, leaves may change from green to yellow or red. Explain in your own words what is happening inside the leaf with regard to plant pigments.   

Answer 1

The green colour of leaves is caused by chlorophyll pigment present inside chloroplast , it produces energy in the form of ATP and Simple Sugars by using sunlight and other chemical and environmental factors. During growing season the green colour of chlorophyll dominates over the all other pigments (masking effect) which are present in leaf . In the fall leaves may changes its colour, because all the components of chlorophyll (mainly chlorophyll a & b) is degraded by the action of the enzyme chlorophyll b reductase to colour less tetrapyrroles (non flurocent chlorophyll catabolite) . After the degradation of chlorophyll the hidden pigment of xanthophylls is revealed, which is the cause of yellow colour of leaves. The red colour is caued by anthocyanins, they starting to syntesize when half of chlorophyll pigment has been degraded.