Answer:
Savanna do not exist in the united states because there are no true tropic climates.
The only exception would be nuclear energy. Heavy elements like Uranium got their stored energy from ancient supernovae, that doesn't come from the sun. And fusing hydrogen is tapping energy that has been around since the Big Bang.
Hope this helped :)
1.Disease resistance of one plant.
<span>2. Food-producing capacity of another.
Hope this helps xD</span>