pho·​to·​sys·​tem ˈfō-tō-ˌsi-stəm How to pronounce photosystem (audio)
: either of two photochemical reaction centers consisting chiefly of photosynthetic pigments complexed with protein and occurring in chloroplasts:
: one that absorbs light with a wavelength of about 700 nanometers

called also photosystem I

: one that absorbs light with a wavelength of about 680 nanometers

called also photosystem II

Example Sentences

Recent Examples on the Web Instead, for a safe, steady energy output, the pigments of the photosystem had to be very finely tuned in a certain way. Quanta Magazine, 30 July 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'photosystem.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Word History

First Known Use

1961, in the meaning defined above

Time Traveler
The first known use of photosystem was in 1961

Dictionary Entries Near photosystem

Cite this Entry

“Photosystem.” Dictionary, Merriam-Webster, Accessed 23 Mar. 2023.

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