Question

In which of the following wavelength, photosystem-$I$ is inactive?

• A. 780 nm
• B. 680 nm
• C. 690 nm
• D. 550 nm

Answer 1

Answer: (A)

780 nm

Answer 2

In $780\, nm$ of wavelength photosystem-I is reactive. In photosystem-I, the photocentre is special chlorophyll-a molecule called $P_{700}$. PS-I has a reducing agent $X,\, Fe-S$ centre, plastoquinone, cytochrome complex and piastocyanin. Part of the spectrum used in photosynthesis has a wavelength between $400-700\, nm$. In photosystem-II a very small amount of special form of chlorophyll-a, called $P_{680}$ is present.