Uploaded October 2023 | Updated September 2026, 10 hours ago

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You can find all my A Level Biology videos fully indexed at freesciencelessons.co.uk/a-level-revision-videos/a-level-biology

In this video, we look at chlorophyll and photosystems. First we explore the role of chlorophyll in the absorption of light energy. We then look at how chlorophyll a forms a reaction centre and how accessory pigments form a light-harvesting system and how together they form a photosystem. Finally, we explore how light energy can lead to the formation of excited electrons and the process of photoionisation.

Image credits:

Visible spectrum
commons.wikimedia.org/wiki/File:Linear_visible_spectrum.svg
Gringer, Public domain, via Wikimedia Commons