DNA, the genetic material of living organisms, is damaged by light in the

A) visible region of the spectrum.

B) ultraviolet region, especially below a wavelength of 320 nm.

C) ultraviolet region, especially above a wavelength of 340 nm.

D) infrared region of the spectrum.

The correct option is B) ultraviolet region, especially below a wavelength of 320 nm.

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.