Question

A reduction of $O_2$ evolution occurs when light wavelength is

• A. More than 680 nm
• B. Less than 580 nm
• C. Less than 660 nm
• D. About 560 nm

Answer 1

The correct option is A More than 680 nm

A) Intensity of light is directly proportional to the rate of photosynthesis. As you rise from low light intensity to higher light intensity, the rate of photosynthesis will increase because there is more light available to drive the reactions of photosynthesis. However, once the light intensity gets high enough, the rate won’t increase anymore because there will be other factors that are limiting the rate of photosynthesis. At a very high intensity of light(more than 680), the rate of photosynthesis would drop quickly as the light starts to damage the plant.

B) Light of wavelength up to 580 nm will not damage the plant and oxygen is evolved.

C) Light of 660 nm is optimum for the evolution of oxygen.
D) Light of 560 nm will not damage the plant.
So the correct answer is 'More than 680 nm'.