Name the three substances that are produced when water molecules are broken down during the light reactions.
During the light reactions of photosynthesis, water molecules are broken down into three substances: oxygen, electrons, and protons (hydrogen ions).
To arrive at this answer, we need to understand the basic process of the light reactions in photosynthesis.
1. Light energy is absorbed by chlorophyll molecules in the thylakoid membranes of the chloroplasts.
2. As a result, electrons in the chlorophyll molecules become energized and are transferred through an electron transport chain.
3. To replenish the electrons lost from the chlorophyll, water molecules are split (photolysis) in a process called photophosphorylation.
4. The splitting of water releases electrons, protons (hydrogen ions), and oxygen gas as byproducts.
5. The released oxygen gas is a waste product and diffuses out of the plant.
6. The electrons and protons generated from the splitting of water are used in the electron transport chain to create energy-rich molecules such as ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate), which are essential for the subsequent dark reactions of photosynthesis.
7. The released protons (hydrogen ions) contribute to the buildup of a concentration gradient, which drives the synthesis of ATP via ATP synthase.
Therefore, when water molecules are broken down during the light reactions of photosynthesis, the three substances produced are oxygen, electrons, and protons (hydrogen ions).