In humans, protein 53 (p53) is a tumor suppressant protein encoded on the p53 gene, which has been mapped to the short arm of chromosome 17. One role of this protein is to facilitate the repair of damaged DNA. In which part of the cell cycle does the p53 gene have the most active role? Answers: F- G1
G- G2
H- S
J-M

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