When does dna replication occur durring cell division

Well, sort of, but not really. There is a bit of ambiguity in what you mean by “cell division”.

In eukaryotes (which I will assume you are studying cell division for), there are two main types of cell division: mitotic and meiotic.

For mitotic cell division, DNA replication occurs during the cell cycle, but in the S phase of interphase … not during mitosis (nuclear division) or cytokinesis (division of the cytoplasm).

However, DNA replication is required in order for mitotic cell division to occur; and DNA replication doesn’t begin until the cell has become ‘committed’ to entering mitosis.

For meiosis, DNA replication also occurs in the S phase of interphase, but only before the first round of cell division (associated with Meiosis I); before the second round of cell division (associated with Meiosis II), DNA replication does not occur.

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.