Question

The red and green lines in the graph shown below indicate the action spectra for chlorophyll pigment molecules during photosynthesis. The black line in the graph below shows the absorption spectrum for green plants. Which of the following best explains the difference between the action spectra and absorption spectrum in photosynthetic tissues?

A) Some wavelengths of light are absorbed by accessory pigment molecules not involved in the photosynthetic process
B) In very bright conditions, chlorophyll molecules absorb more photons of light that can be used in photosynthesis
C) At higher temperatures, chlorophyll pigment molecules become less efficient and must absorb more photons than normal to excite electrons
D) The process of photorespiration causes a discrepancy between the wavelengths of light absorbed and the excitation of electrons

Answer 1

Hint: Photosynthesis is a process that is carried out by green plants and some other organisms for the conversion of light energy into chemical energy that is useful to them.

Complete answer:
During photosynthesis pigments play an important role in the absorption of light. These pigments are chlorophylls, carotenoids, etc. each of which absorb light at a particular wavelength. When any of these pigments absorb light it leads to excitation of an electron that takes the electron to a higher energy level from where a series of events takes place that finally leads to the formation of chemical energy.

Absorption spectrum is defined as all the wavelengths of light absorbed by different pigments. Action spectrum in turn includes all the wavelengths that are used for the process of photosynthesis. So by this we can conclude that all the wavelengths of light absorbed by the pigments are not utilised in the process of photosynthesis.

So the correct option is (A) Some wavelengths of light are absorbed by accessory pigment molecules not involved in the photosynthetic process.

Note: Photosynthesis is thus a crucial and complex process governed by important pigments which absorb light at different wavelengths leading to the formation of food and energy that can be utilized for other vital processes and also helps to provide oxygen which is required for survival of all aerobic organisms.