( ( Name ( ( the structure ) ( formed ( by ( these ( two cells ) ) ) ) ) ) . )
(ROOT (S (VP (VB Name) (NP (NP (DT the) (NN structure)) (VP (VBN formed) (PP (IN by) (NP (DT these) (CD two) (NNS cells)))))) (. .)))
Name the structure formed by these two cells.
(ROOT (S (NP (CD Two) (NNS membranes)) (VP (VBP form) (NP (NP (DT the) (NN mitochondrion) (NN structure)) (PP (IN of) (NP (DT a) (NN cell))))) (. .)))