The correct option is B Ethidium bromide stained DNA can be seen under exposure to UV light
Introduction to agarose gel electrophoresis:
Agarose gel electrophoresis is the process of separation of DNA fragments in an electric field based on their size.
● The DNA fragments and size markers are loaded onto the gel well and current is passed through the gel.
● The DNA being negatively charged, moves towards the positive electrode during gel electrophoresis.
● The smaller the size of the molecule, the faster and farther it travels. This is how the fragments are separated.
Visualisation of DNA in agarose gel electrophoresis:
DNA is a transparent molecule. To visualise it in the agarose gel, a positively charged dye Ethidium bromide (EtBr) is added in the agarose gel or electrophoresis buffer.
● This dye intercalates in between the DNA and gives orange fluorescence upon exposure to UV light.
● Thus, DNA is visualised on the exposure of UV light and orange bands of DNA are observed on the agarose gel.
Final answer
d. Ethidium bromide stained DNA can be seen under exposure to UV light