Question

Decline in quantum yield was noticed by Emerson at a wavelength of

• A. 400-450 nm
• B. 600-650 nm
• C. 650-680 nm
• D. More than 680 nm.

Answer 1

The correct option is D More than 680 nm.

During the light phase of photosynthesis, evolution of oxygen takes place. The number of light quanta required for evolution of one molecule of oxygen is called quantum yield. It is a unit to measure the rate of photosynthesis. Beyond wavelengths of 680 nm, decline in quantum yield is observed. Due to decline in quantum yield, there is a decrease in photosynthetic yield compared to red region of electromagnetic spectrum. This decrease is known as Red drop. It was observed by Emerson. He performed his experiment on Chlorella plant.