The backbone of a DNA molecule is: ( ) A: made up of sugars B: made up of nitrogenous bases C: made up of phosphate groups D: made up of alternating phosphate and sugar groups E: made up of alternating sugars and nitrogenous base

The<br/>backbone of a DNA molecule is () A: made<br/>up of sugars B: made<br/>up of nitrogenous bases C: made<br/>up of phosphate D: made<br/>up of alternating phosphate and sugar groups E: made<br/>up of alternating sugars and nitrogenous base

The major nitrogenous waste of bony fishes is ( ). A: ammonia B: urea C: uric acid D: guanine E: creatine

Early members of the class Reptilia were the first to produce( ). A: neotenic larvae B: amniotic eggs C: urea as a nitrogenous waste D: tadpole larvae E: isolecithal eggs

The backbone of a DNA molecule is<br/>_________.() A: made up of sugars alone B: made up of nitrogenous bases alone C: made up of phosphate groups alone D: made up of alternating phosphate and<br/>sugar groups

Of the following environmental<br/>problems, the one that does not belong to environmental pollution is<br/>( <br/>). A: The noise from the rolling<br/>mill spread to the nearby residential area B: Waste water from the<br/>nitrogenous fertilizer plant is discharged into a nearby river C: The waste gas from the coking<br/>plant is discharged into the sky D: Serious water and soil erosion<br/>in the Huangtu Plateau region