Pretend you are a new scientist studying the past. Your assignment is to utilize the geologic scale as your main tool for research. What important functions does the geologic time scale serve to you? What will you be able to share with others from utilizing it?

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.

you click your profile picture in the top right corner and it says edit profile.