Which is a biotic factor that affects the size of a population in a specific ecosystem?
a. average temperature of the ecosystem
b. type of soil in the ecosystem
c. number and kinds of predators in the ecosystem
d. concentration of oxygen in the ecosystem

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.

Acommon kind of mechanical weathering is called

How do plants obtain more sunlight a.) they lean towards the light b.)they grow straight up c.) they only live in sunny areas, like the tropics d.) they stay low to the ground