19. draw the nucleus of a cell and label the: a) double layered structure which encloses the nucleus. b) visible entangled mass of thread like structures. c) a darkly stained round structure inside the nucleus.

showing a photograph would make this a hell of alot easier

its 42

i say its d?

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.