Agroup of students are walking in the park, and one of them takes a picture of a pollen grain that is being blown by the wind. what caption can the student use for this picture?
a. gene mutation in action
b. gene flow at work
c. genetic drift as it happens
d. natural selection in progress

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