hope this helps a little :-)
Answer: a leaf most times has a large surface area, it has this so that it can absorb more light. and the upper waxy layer on the leaf is there to prevent water loss
Answer:
you meant what are the main sources
they are: fossil
clean energy
energy storage
hydrogen& fuel
electric power
This may be economically helpful to the tree farmers because the pine trees will not die because they are now resistant to the disease. The tree farmers will have a better harvest and make more money off of it.