Which of the following represents ways nitrogen can enter the soil? I. Photosynthesis
II. Sunlight
III. Rainfall

III only
I and II
I and III
I, II and III

PLEASE HELP

Compare and contrast nutrient limitation in soil vs. nutrient limitation in aquatic ecosystems

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.

What prevents odyssey from killing the sleeping cyclops