Which three factors limit descriptive and comparative investigations? O A. The way you must write hypotheses B. The number of variables you can have I C. The number of observations you can make D. The features of objects that you cannot see E. The amount of time or money required.

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.

Why is it important to study each branch of earth science?

Reactants undergo chemical reaction to form products. this chemical equation represents one such reaction. the coefficient for one of the reactants or products is incorrect. which part of the chemical equation is incorrect?