Which of the following is NOT a characteristic of most ionic compounds? When dissolved, they conduct an electric current.
They have low melting points
They tend to be solids
They are usually composed of metallic and nonmetallic elements

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.

Nephrons, the functional unit of kidneys, are responsible for formation of urine. the sentences describe situations that are the result of problems in the urine formation process. for the nephron shown below, match each situation to the step in the urine formation process where the problem lies.

Describe the relationship between isotonic solutions, equilibrium, and water movement into and out of a cell.