Expert: Walter Hintz - 11/24/2006

Question
Could you please explain the following questions:



1- Why does chlorophyll appear green?

2- In darkness, what happens to starch formed in a leaf?

3- What causes leaves to turn from green to yellow and red in autumn?

4- Of what value to plants is starch?

5- What is the significance of electron transport in the photochemical (i.e., light-dependent) reactions of photosynthesis?

Thanks in advance.

Answer
Hello Esraa
1.  All wave lengths of light except green are absorbed. Green is reflected.
2.Some starch is broken down to glucose to provide energy for the plant.  Most of the starch is stored
3.The yellow and red pigments are already in the leaf masked by the green.  The green is broken down first and the other pigments appear
4. Starch is stored energy
5.Photons of light bump electrons to higher energy levels (orbitals) They gradually return to the lower levels releasing energy to be stored in ATP.  The electron transporters move them down.