In the centre of the photosystem II (left), four manganese atoms (purple), five oxygen atoms (red) and one calcium atom (green) form the oxygen-evolving complex. The cluster (right) contains only five ...

Note: This video is designed to help the teacher better understand the lesson and is NOT intended to be shown to students. It includes observations and conclusions that students are meant to make on ...

BERLIN (AP) — Scientists say they have detected significant amounts of molecular oxygen coming out of a comet, an unexpected find that may have implications for the search for alien life and ...