Form a hypothesis: a scientist uses radioactive nitrogen to label the nitrogenous bases of the dna of a cell. then the dna is allowed to replicate, and the new strands take up non-radioactive bases. do one, both, or neither of the daughter cells have radioactive dna? explain.

The new strands took only non-radioactive bases during their replication. This implies that the radioactive bases did not get incorporated in the new strands.     Also, according to semi-conservative mode of replication, one parental and one newly synthesized strand goes to the daughter cells. Since it is a hypothetical situation according to which parental strand has radioactive labeling, the radioactive strand will pass on to both the daughter cells.

significant amounts of nitrogen oxides, carbon monoxide, and other pollution

explanation:

passenger vehicles are a major pollution contributor, producing significant amounts of nitrogen oxides, carbon monoxide, and other pollution. in 2013, transportation contributed more than half of the carbon monoxide and nitrogen oxides, and almost a quarter of the hydrocarbons emitted into our air.

"a.) well–developed vascular system."