There are organisms at each level as you move up an energy pyramid. Only energy is available to the next level in a food chain.

A food web is more than a food chain.

Assume that a student is given two different models of bacteria, with one model consisting of big bacteria and the other consisting of small bacteria. how can the student demonstate the theory of endosymbiosis using the models

Melting glaciers is a serious threat to the environment what is the possible consequence of melting glaciers on polar bears?

Humans are believed to have evolved in coastal regions in east africa. the region had an abundant supply of fish for early humanoids to eat. when scientists analyze the fads gene they see an interesting pattern. people whose families have lived in this area of east africa for generation show a high level of diversity in alleles for the fads gene. conversely, people whose families had migrated inland a moderate distance from sources of fish showed a much lower diversity for fads gene alleles. additionally, the fads alleles found in people whose family has lived inland for generation are almost all gene alleles which produce fads proteins with a high level of function and activity. how do anthropologists explain this?