Explain why volcanic soil (aridisols) is fertile.

Scientist have long study the earths climate by looking at which of the following? the earths orbit. the earths rock layers. the antarctic ice. the earths oceans.

What are some aquatic organisms that live in cold water temperatures?

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.