What is the direction of force of gravity ?​

An atom of nitrogen had seven protons in its nucleus. how many electrons does it have

Which animal group is the largest and contains more species from all the other living groups combined? is it mammals or

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.