The term facultative anaerobe refers to an organism that a) doesn't use oxygen but tolerates it. b) is killed by oxygen. c) uses oxygen or grows without oxygen. d) requires less oxygen than is present in air. e) prefers to grow without oxygen.

the answer is B because 'a facultative aerobe is an organism that makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation or anaerobic respiration if oxygen is absent. An obligate aerobe, by contrast, cannot make ATP in the absence of oxygen, and obligate anaerobes die in the presence of oxygen'.

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.