The Sun is the energy source for almost all life on earth.
Any light that exist was already emitted from somewhere. Any light that is absorbed, is destroyed, and is not emitted light; though, it may lead to light being emitted.
The effect of chemical pollution on insects living in a pond i think
I am not sure what the answer(s) for, "which is not a major function of the kidney?" is but I can guess that your answer for that question might be, regulation of blood cell size. Also, the normal ph range of urine in humans is 6! I hope this helps!