Question

Which pigment acts directly to convert light energy to chemical energy?
(a)Chlorophyll a
(b)Chlorophyll b
(c)Xanthophyll
(d)Carotenoid

Answer 1

This is also called a universal photosynthetic pigment as it is found in all photosynthetic plants except bacteria and is responsible for the highest absorption of light energy for conversion to chemical energy.

Complete answer:
Chlorophyll-a is the pigment that works on converting light energy into the energy of chemicals. It is also called the primary photosynthetic pigment because it performs the first reaction of photosynthesis which involves the conversion of sunshine energy into energy. The energy produced by pigments other than Chlorophyll-a is finally handed over to chlorophyll-a through electron spin resonance.

Additional Information: -Chlorophyll-a also transfers resonance energy in the antenna complex, ending in the reaction center where specific chlorophylls are located.
-Chlorophyll-a absorbs most of the energy from wavelengths of violet-blue and orange-red light. It also reflects green-yellow light, and as such contributes to the green color of most plants.
-Chlorophyll synthase is the enzyme that catalyzes the reaction and completes the biosynthesis of chlorophyll-a.
-Other photosynthesis pigment chlorophyll-b and carotenoids that include carotenes and xanthophylls are called accessory pigment.
-These accessory pigments absorb light energy of different wavelengths, and in this way broadens the spectrum of light absorption.
-Chlorophyll-a can also be found in very small quantities in the green sulfur bacteria, and anaerobic photoautotroph. These organisms do not produce oxygen but use bacteriochlorophyll and some chlorophyll-a also.
So, the correct answer is 'Chlorophyll a'.

Note: -Electron spin resonance is associated with free-radical signals generated in various chlorophyll species during the photosynthetic process.
-This photosynthetic pigment chlorophyll-a is very much essential for photosynthesis in eukaryotes, cyanobacteria, and prochlorophytes because of its role as the primary electron donor in the electron transport chain of photosynthesis.
-Chlorophyll-a is mostly present in the upper part of the leaf to be exposed to more sunlight.