Reese learns in class that hot lava in a volcano is liquid rock. What would be a good model to help Reese understand how rock can change into a liquid? A. a ball rolling down a hill
B. chocolate mixing with milk
C. ice melting into water
D. clothes drying in a dryer

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.

All organisms contribute some water to the water cycle by conducting

In an hydrogen ion pump the energy is used to join small molecules together to make larger ones which factor most likely has the greatest effect on the number of molecules mitochondria can produce