How do american elm trees reproduce

What are some things that limit population growth?

The breakdown of food is accomplished by enzymes. a. physical b. chemical c. mechanical d. none of the above

What is point source pollution of an aquatic ecosystem? a) pollution of freshwater sources b) pollution from many sources that combine into one c) pollution that occurs over a wide area; water that runs off from fields, parking lots, and other land surfaces d) pollution that can easily be identified with a single discharge source, such as an open pipe which drains into a body of water