Emerson Enhancement Effect MCQ - Practice Questions with Answers

Quantum Requirement: The number of light quanta required for the evolution of one molecule of oxygen is called quantum requirement. Emerson calculated it to be 8.

Quantum Yield: The amount of oxygen evolved by one quantum of light is called quantum yield. It is calculated to be 12.5%

Red Drop Phenomenon: 

While working with Chlorella algae, Emerson and Lewis noticed a sharp decrease in quantum yield at a wavelength greater than 680 nm, while determining the quantum yield of photosynthesis in chlorella using monochromatic light of different wavelengths.
Since this decrease in quantum yield took place in the red part of the spectrum, the phenomenon was called the red drop.
Later, they found that the inefficient far-red light beyond 680 nm could be made fully efficient if supplemented with the light of a shorter wavelength (blue light).
The quantum yield from the two combined beams of light was found to be greater than the sum effects of both beams used separately.
This enhancement of photosynthesis is called Emerson’s Enhancement Effect.

Conclusion:
This phenomenon confirmed the involvement of two distinct photochemical reaction centres.
One reaction centre is driven by a shorter wavelength (<680 nm) and the other by a longer wavelength (>680 nm).