The answer for the above question is Mutation.
Mutations are random spontaneous changes that occur suddenly in the DNA. A single mutation can have a large effect, however in may cases evolutionary changes are based on the accumulation of many mutations. The gene flow is any movement of genes from one generation to another and is an important source of mutation
Answer:
The correct option is <em>B) ultraviolet region, especially below a wavelength of 320 nm.</em>
Explanation:
Ultraviolet light carries an enormous amount of energy in it. It is invisible to the human eye. When UV light with enormous energy and wavelength lesser than 320nm, hits the DNA, it causes changes in the structure of the DNA. Mostly, it affects the thymine nitrogenous base regions and forms pyrimidine dimers. The structure of the DNA changes on all the sites where dimers form and hence, they cannot be properly transcribed.
