In what era did dinosaurs first appear?

Dna replication or repair occurs in a cell in all of thw following situations except when

Up to what percentage of the world's flora consisted of cycads during the triassic period? 100% 75% 50% 20%

Agene editing technology called crispr-cas9 uses cellular machinery to change the cell's genetic material. how might this technology be useful in treating diseases like cancer?