true or false: the seasons are caused by earths orbit around the sun in combination with the tilt of earths axis

Are substances released into the environment that in excess amounts cause damage

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 ocean is on the eastern coast of north and south america? arctic ocean indian ocean pacific ocean atlantic ocean