Question

Red drop occurs in wavelength of

• A. 492 nm
• B. 535 nm
• C. 586 nm
• D. 680 nm.

Answer 1

The correct option is D 680 nm.

Beyond wavelengths of 680 nm i.e. far red region, there is a decrease in photosynthetic yield compared to red region of electromagnetic spectrum. This decrease is known as Red drop. Red drop occurs because of the decrease in quantum yield. Quantum yield is the number of oxygen molecules released per light quanta absorbed. Red drop effect was proposed by Emerson and Lewis. They performed their experiment on chlorella plant.