Question

Emerson defined red drop as decline in the quantum yield of photosynthesis at wavelength of

• A. 460 nm
• B. 670 nm
• C. 680 nm
• D. More than 680 nm

Answer 1

The correct option is D More than 680 nm

Emerson defined red drop as decline in the quantum yield of photosynthesis at wavelength beyond 680 nm.

Red drop effect - Wavelengths beyond 700nm are apparently of insufficient energy to drive any part of photosynthesis. So, a huge drop in efficiency has been noticed at 700nm. In other words there is a sharp decrease in quantum yield at wavelengths greater than 680nm. This decrease in quantum yield takes place in the red part of the spectrum. The number of oxygen molecules released per light quanta absorbed is called as quantum yield of photosynthesis. This effect was first of all noticed by Robert Emerson.