試題詳解

20. Biofuels are mainly produced by ______.
(A) plants that convert hemicellulose into gasoline
(B) plants that are easy to grow in arid environments
(C) transgenic crops that have cell walls containing ethylene
(D) the genetic engineering of ethanol-generating genes into plants
(E) the breakdown of cell wall biopolymers into sugars that can be fermented