What sorts of signals does the brain use to communicate sensations, thoughts and actions?

The single cells in the brain communicate through electrical and chemical signals. Let me know if this helps!!!

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)

the ozone layer acts as a filter for the shorter wavelength and highly hazardous ultraviolet radiation (uvr) from the sun, protecting life on earth from its potentially harmful effects. when the sky is clear, there is an inverse relationship between stratospheric ozone and solar uvr measured at the earth's surface.