The parts of a cell are so dependent on each other that if just one part does not work right, the entire cell may not function properly. This is an example of complex .

The gene that causes sickle-cell disease is present in a higher percentage of residents of sub-saharan africa than among those of african descent living in the united states. even though this gene causes sickle-cell disease, it also provides some protection from malaria, a serious disease that is widespread in sub-saharan africa but absent in the united states. discuss an evolutionary process that could account for the different percentages of the sickle-cell gene among residents of the two regions.

The similarities of organisms in which two areas numbered above provide the best evidence for common ancestry between organisms in both locations?

Which of the following can be reduced by the use of renewable energy sources? a. social costs b. economic costs c. environmental costs d. all of the above select the best answer from the choices provided a b c d