How long does it take new species to form on earth?

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.

Buuy which of the following did you include in your response? organs perform specific functions in the body to keep it alive. organelles perform specific functions in cells to keep them alive. done

Look at the photo of the leaf, which term best describes this leaf ? a-simple. b-parallel. c-lobed. d-tooth.