Cells that perform this process become differentiated after the transcription factor NtcA facilitates expression of additional cell walls and cyano·phycin plugs. An incomplete genome labeled “UCYN-A” (“U-C-Y-N-A”) was recently found to belong to a plastid capable of performing this process within the cocco·litho·phore B. bigelowii (10[2])(“bigelow-ee-eye”). A morphological change that facilitates this process begins by the curling of a hairlike structure, a behavior that is itself induced by Nod factor expression. (10[1])This process occurs (10[1]-5[1])primarily (10[1])in photosystem (10[1])II–deficient cells known as heterocysts (10[1])in some (10[1])filamentous cyanobacteria. (-5[1])Root nodules (10[1])create an anoxic environment that allows (10[1])rhizobia (10[3]-5[1])to perform (10[3])this (10[1])process in (10[1])the roots of legumes. (10[1])For (10[1])10 points, name this process in which biologically useful molecules (10[1])are created from the most common gas in the atmosphere. ■END■ (10[3])