Final answer:
Ethidium Bromide is dangerous because it is mutagenic and carcinogenic, but it is helpful for molecular biology because it can intercalate with DNA and be visualized with UV light.
Step-by-step explanation:
Ethidium Bromide (EtBr) is dangerous because it is a mutagenic compound that can cause genetic mutations and has been shown to be carcinogenic. It can also be absorbed through the skin and is toxic to many organs. However, EtBr is also helpful for molecular biology because it is a fluorescent dye that can intercalate with DNA, allowing scientists to visualize nucleic acids on agarose gels. When exposed to UV light, EtBr-treated nucleic acids light up, making it easier to study DNA and RNA.