Question

During photosynthesis, the energy from sunlight is used to split water molecules. What happens to the hydrogen ions that are split from the water molecules?

Answer 1

During photosynthesis, hydrogen ions from the splitting of water are used to create a chemiosmotic gradient for ATP production and to maintain the flow of electrons through the electron transport chain.

Step-by-step explanation:

During photosynthesis, the hydrogen ions that are split from the water molecules are used in the light-dependent reactions. The process begins in the photosystem II (PSII) reaction center, where light energy is harnessed to extract electrons from water molecules. This process is known as photolysis and results in the production of hydrogen ions, electrons, and oxygen atoms.

The hydrogen ions (H+), also known as protons, are important in establishing a chemiosmotic gradient across the thylakoid membrane within the chloroplast. As electrons move through the electron transport chain, from PSII to photosystem I (PSI), protons are pumped into the thylakoid lumen, creating a high concentration of hydrogen ions, which leads to a low pH environment inside the lumen.

The gradient produced by the accumulation of protons is then used by ATP synthase to generate ATP, which is vital for the subsequent stages of photosynthesis, including the Calvin cycle. Additionally, the electrons released during water splitting replaces those that were lost from chlorophyll in PSII, ensuring the continuous flow of electrons through the system to ultimately reduce NADP+ to NADPH.

Answer 2

During photosynthesis, when hydrogen ions are split from the water molecules, this is called photolysis. The hydrogen atoms are then transferred to NADP+ molecule, making it NADPH. These stored hydrogen along with electrons will be used for the next cycle while the oxygen that is split from the water molecules is released to the atmosphere.