How are primary and secondary succession similar and how are they different?

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 equation is used to calculate the magnetic force on a charge moving in a magnetic field

What is the relationship between absorbance of light and the rate of photosynthesis?