Natural selection causes populations to remain constant through changing environments populations to never change populations to change over time populations to lose their competitive advantage

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.

How is the carbon cycle related to global warming ?

How can you tell the difference between rough er from smooth er?