A group of biological communities that interact with the physical environment is

Which of the follow describes a disadvantage secondary sources have compared to primary sources?

Which of the following types of pollution is most responsible for large numbers of deaths worldwide because of unsafe drinking water? (a) nutrient pollution (b) thermal pollution (c) pathogen pollution (d) sediment pollution

Explain why it’s important for scientists to study the sun. list at least two challenges researchers face when examining earth’s nearest star.