Question

Emerson effect is related to
A.Decrease in photosynthesis in presence of high light intensity
B.Decrease in photosynthesis when lights of two different wavelengths are provided together
C.Increase in photosynthesis in presence of monochromatic light
D.Increase in photosynthesis when lights of two different wavelengths are provided together.

Answer 1

When chloroplasts are exposed to light with a wavelength of 680 nm (deep red spectrum) and more than 680 nm, the Emerson effect occurs, which increases the rate of photosynthesis (far red spectrum). When both wavelengths of light are combined, the rate of photosynthesis is much larger than the combination of red and far red light photosynthesis rates. The effect was the first proof that two photosystems working together in photosynthesis, each processing distinct wavelengths.

Complete answer:
In 1957, Robert Emerson coined the term "eponymous effect." He mentioned this in his paper.
When plants are exposed to light with a wavelength higher than 680 nm, just one photosystem, PS700, is active, resulting in the production of only ATP.
The rate of photosynthesis was very poor when plants were exposed to light with a wavelength shorter than 680 nm.
Because both photosystems were functioning together at the same time while delivering both shorter and longer wavelengths of light, the efficiency of the process rose, resulting in a greater yield.
When Emerson exposed green plants to various wavelengths of light, he observed that photosynthetic efficiency dropped sharply at wavelengths higher than 680 nm, despite the fact that chlorophyll still absorbs light in this area of the spectrum (chlorophyll is the green pigment in plants - it absorbs mainly the red and blue wavelengths from light).
The effectiveness of the plants reduced when they were exposed to short-wavelength light (less than 660 nm). Emerson then simultaneously exposed the plants to both short and long wavelengths, resulting in a significant improvement in efficiency. He came to the conclusion that photosynthesis must include two distinct photosystems, one powered by short-wavelength light and the other by long-wavelength light (PS1 and PS2). They collaborate to improve efficiency and transform light energy into forms that the plant can absorb.

Hence option d is correct.

Note:
The light generates an increase in energy by excitatory the chlorophyll molecules in the reaction centre. As the molecule becomes less excited, its energy is transferred to the next photosystem, which accomplishes the same thing and creates energy-carrying organic molecules, via a chain of electron carriers.