Question

Absorption spectrum is a technique in which the specific absorption of a wavelength of light is recorded and plotted in the form of a graph. Below are some of the statements which tell us about the absorbance of specific chemicals. Justify the reason behind their absorbance of specific wavelengths?

• A. Proteins absorb mainly lights of wavelength 280 nanometers due to the presence of aromatic amino acids.
• B. DNA shows absorbance peak at 260nm which is similar to RNA peak.
• C. Different photosystems in light reactions have different absorbances due to difference in the amount and density of light harvesting substances.
• D. All of the above

Answer 1

Answer: (D)

All of the above

Answer 2

Proteins absorb at 280 nm due to aromatic amino acids (Tryptophan, Tyrosine). DNA and RNA absorb at 260 nm due to conjugated double bonds in their nitrogenous bases. Different photosystems have varied absorption spectra because of differences in their pigment composition (types and ratios of chlorophylls, carotenoids) and the influence of their specific protein environments on pigment absorption. All given statements are correct.