Question

multiple choice question
in the light-dependent reactions of photosynthesis, electrons given up by the reaction center chlorophyll in photosystem ii are replaced by those from

a water molecule.

another pigment.

nadph.

atp.

Explanation:

In the light - dependent reactions of photosynthesis, photosystem II splits water molecules ($\ce{H_2O}$) into electrons, protons (hydrogen ions), and oxygen. The electrons from the split water molecules are used to replace the electrons that the reaction - center chlorophyll in photosystem II has given up. Another pigment does not supply these replacement electrons. NADPH is a product of the light - dependent reactions (specifically from the electron transport chain in photosystem I), not a source of electrons for photosystem II. ATP is also a product of the light - dependent reactions (from photophosphorylation) and is not a source of electrons for photosystem II.

Answer:

a water molecule.