What goes up but never ever comes down?

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.

Suggest why placing wheels under a heavy box reduces the neccessary force required to push it along at a constant speed.

Clara wrote the following hypothesis for an experiment about acidophilic bacteria. bacteria cells will stop dividing in a basic (alkaline) environment because of the high ph. which statement is the best way to restate the hypothesis so that it is more specific? growing acidophilic bacteria in some environments will cause the cells to stop dividing because of ph. if the ph of their environment is changed, acidophilic bacterial cell division will be affected. if the environment of acidophilic bacterial cells becomes alkaline, the bacteria will stop dividing. the more alkaline an environment, the less cell division will occur in bacteria.