How does ultraviolet radiation harm living things?

Which element is used in photosynthesis found in atmosphere and fixed by bacteria?

Aristotle classified animals according to their a. habitat and mating behavior c. mating behavior and relatedness b. habitat and physical differences d. physical differences and mating behavior

The greenhouse effect a. something that has occurred for millions of years b. an unnatural phenomenon caused by humans that maintains earths temperature range. c. the results of the differences in the angle of the suns rays d. an unnatural phenomenon that causes heat energy to be radiated back into the atmosphere