Knowledge that is gained by observing natural events in condition is known as

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.

Which two criteria must be met before scientist can use radiocarbon dating? explain your answer

What materials must dams have to produce electricity, and what must occur?