How organisms could be harmed by high levels of salt from roadways, and expressing your opinion about whether it should continue and why.

a unit of heredity that is transferred from a parent to offspring and is held to determine some characteristic of the offspring.

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.