Question

Absorption spectrum of chlorophyll a shows maximum absorption in ______ and ______
A. regions of light
B. blue and green
C. blue and red
D. red and green
E. red and far-red

Answer 1

Hint: The absorption spectrum refers to the wavelength of light which can be absorbed by a given compound. Absorption is guided by the relationship between the frequency and wavelength of light with that of the compound's ability to absorb photons emitted by the light. Chlorophyll has an absorption spectrum between the range of 400 to 700nm which constitutes the visible electromagnetic spectrum.

Complete answer:
Absorption of light is the ability of the electron within a compound to get excited and move to a higher state. In simpler terms, a compound will only absorb electromagnetic radiation of a particular wavelength as the electrons within that compound can only absorb or get excited by that particular wavelength. It is of vital importance in analytical chemistry, where each compound having a distinct absorption spectrum can be identified by subjecting it to light emission. Several tools such as a spectrophotometer, laser emission, photoacoustic spectroscopy, etc. have been built based on the principle of absorption to identify chemical compounds. Chlorophyll is a pigment present within plants. Chlorophyll is the key pigment produced by the chloroplasts within the plant cell which initiates photosynthesis. The absorption spectrum of chlorophyll is in the visible range from 400 to 700nm. This begins with the 400nm meter region where the light is blue to the 700nm region, where the light is red. The absorption spectrum for chlorophyll can also be called the blue-red spectrum.
Therefore, the correct answer is option B.

Note: The visible spectrum holds all the colours that we can see and or distinguish. 400 to 700nm in the visible spectrum and begins with blue light and ends with the red. Chlorophyll can absorb the entirety of the visible spectrum and therefore, the correct answer is blue red and not blue-green or red-green as these denote only half the visible spectrum. Far-red denotes the infrared region which is not under the visible spectrum, chlorophyll cannot absorb radiation in this region either.