Question

When light energy excites electrons in photosystem II, where do the electrons to replace them come from?

A. ATP
B. Photosystem I
C. The light energy
D. Split water molecules

Answer 1

After the electrons have been excited with light energy in Photosystem II, the replacement electrons come from the splitting of water molecules D. I believe is the correct response.

Answer 2

The correct answer is D. Split water molecules.

Several pigments absorb light energy from the sun and passes it to P680 reaction center of photo-system II.

It then uses this energy to split the molecule of water and passes the free electron to the electron carrier known as plastoquinone.

`2H_(2)O` →
`4H^(+) + 4e^(-) + O_(2)`

The electron is then passed to phot-system I via cytochrome
`b_(6)f`.

The overall passage of electron in this electron transport chain can be summarized as:

`H_(2)O` → PS II → plastoquinone → cytochrome
`b_(6)f` → PS I → NADP