Question

Which of the following represent the correct molecular formula of chlorophyll b
(a) ${ C }_{ 55 }{ H }_{ 72 }{ O }_{ 5 }{ N }_{ 4 }{ Mg }$
(b) ${ C }_{ 55 }{ H }_{ 72 }{ O }_{ 5 }{ N }_{ 4 }{ Mg }$
(c) ${ C }_{ 55 }{ H }_{ 72 }{ O }_{ 4 }{ N }_{ 4 }{ Mg }$
(d) ${ C }_{ 55 }{ H }_{ 70 }{ O }_{ 5 }{ N }_{ 4 }{ Mg }$
(e) ${ C }_{ 55 }{ H }_{ 70 }{ O }_{ 6 }{ N }_{ 4 }{ Mg }$

Answer 1

Hint: Accessory pigment in a plant that contains 55 carbon molecules, 70 hydrogen molecules, magnesium, four nitrogens, and six oxygen atoms. It protects major photosynthetic pigment from photo-oxidation

Complete answer:
Color that we see in leaves is not due to a single pigment but due to four pigments shown in Chromatographic separation of leaf pigment, they are chlorophyll a, chlorophyll b, xanthophylls, and carotenoids. The molecular formula ${ C }_{ 55 }{ H }_{ 72 }{ O }_{ 5 }{ N }_{ 4 }{ Mg }$ represents chlorophyll-a and the molecular formula ${ C }_{ 55 }{ H }_{ 70 }{ O }_{ 6 }{ N }_{ 4 }{ Mg }$ represents chlorophyll b.

Additional Information: - In the chromatogram chlorophyll-a appears as bright or blue-green color whereas chlorophyll b appears in yellow-green color. Xanthophylls appear yellow in color and carotenoids appear yellow-orange in color.
- Pigments are substances that have the ability to absorb light at specific wavelengths.
- Chlorophyll-a absorbs light at different wavelengths. In the blue and the red regions, the maximum absorption of chlorophyll-a is seen and also shows a higher rate of photosynthesis.
- The chief pigment of photosynthesis chlorophyll-a
- In the blue and red regions of the spectrum, most of the photosynthesis takes place

So, the correct answer is '${ C }_{ 55 }{ H }_{ 70 }{ O }_{ 6 }{ N }_{ 4 }{ Mg }$’

Note: - Other thylakoid pigments like chlorophyll b, xanthophylls, and carotenoids which are called accessory pigments also absorb and transfer the energy to chlorophyll a.
- They not only activate a wider range of wavelengths of incoming light that is utilized for photosynthesis but also protect chlorophyll-a from photo-oxidation.