Question

What happens to water molecules in the light reactions?

Answer 1

Explanation:

Light reactions -- light energy in the presence of chlorophyll -- splits water. Splitting water into oxygen gas, hydrogen ions and electrons produces the energy for subsequent electron and proton transport and provides the energy to produce the sugars the plant needs. These subsequent reactions form the Calvin cycle.

Answer 2

The water is split during the light reaction to form oxygen gas and hydrogen ions. The hydrogen ions are used by the chloroplast to produce ATP.

Explanation:

• In the light reactions, the energy of light is used to split water, stripping a pair of electrons from it (and causing the hydrogens to be lost), thus generating molecular oxygen.

• Splitting water into oxygen gas, hydrogen ions and electrons produces the energy for subsequent electron and proton transport and provides the energy to produce the sugars for the plant needs.

• These subsequent reactions form the Calvin cycle.

• In the process of photosynthesis, water provides the electron that binds the hydrogen atom (of a water molecule) to the carbon (of carbon dioxide) to give sugar (glucose).

• Water acts as a reducing agent by providing $H^{+}$ ions that convert $NADP$ to $NADPH$.