Which of the following is not a function of saliva?
a) saliva dissolves food chemicals so they can be tasted. b) saliva contains enzymes that begin the chemical breakdown of proteins. c) saliva moistens food and compact it into a bolus. d) saliva cleanses the mouth.

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.

answerwestern plateau,     central lowlands,     great dividing range;