Blue-green algae plays an important part in the nitrogen cycle by recycling ammonia into nitrates and by "fixing" elemental nitrogen into a form that can be used by organisms. a decrease in this alga would have a large negative impact on the marine environment. however, not all algae play the same role in the environment. explain how a bloom (a drastic increase) of algae can cause problems in the marine environment.

1. variations in a population of moths allow for some of its members to be able to adapt to environmental changes. the better adapted of the moths will be able to survive the change and thus prevail as the “fittest” of the species. (a) describe three mechanisms in which variation can occur within a species population. (b) explain which mechanism or mechanisms would be responsible for the survival of a population of peppered moths better than white moths in an environment affected by industrial soot. justify your answer.

Elephants in the savanna regions of africa dig holes in dried up river beds to reach water lying just below the surface. these holes provide drinking water for other animals as well. so, without the elephants, many animals might otherwise die from lack of water during the dry season. the location in which the elephants live is an example of a/n and the role they play in creating water holes is an example of a a) ecosystem; habitat b) community; niche c) habitat; niche d) niche; habitat

2. if someone had the list of traits you provided in question 1, do you think he or she would be able to find you in a group of 1000 people? why or why not? if not, what other information encoded in your genes might distinguish you from the others in the group? what are other traits that are encoded for by dna?