scientists used radioactive hydrogen to make water. They grew plants using the radioactive water. What happened to the radioactive hydrogen during photosynthesis?
During photosynthesis, plants do not directly incorporate water molecules into their cellular components. Instead, they break down water molecules into hydrogen ions (H+), electrons (e^-), and oxygen molecules (O2), in a process known as photolysis.
Specifically, during the light-dependent reactions of photosynthesis, light energy is utilized to excite electrons in the chlorophyll molecules within the plant's chloroplasts. These excited electrons are then passed through an electron transport chain, generating energy-rich molecules such as ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate).
In this process, the electrons come from the splitting of water molecules. The reaction involves the transfer of four electrons from two water molecules, resulting in the release of one molecule of O2 as a byproduct. The hydrogen ions (H+) generated during the photolysis of water are utilized in the formation of ATP and NADPH.
If scientists used radioactive hydrogen (tritium) to make water and then supplied this radioactive water to the plants, the radioactive hydrogen would still be present as hydrogen ions (H+) in the water. However, it is important to note that tritium, a radioactive isotope of hydrogen, is unstable and undergoes radioactive decay over time, emitting beta radiation in the process.
Therefore, during photosynthesis, the radioactive hydrogen ions from the radioactive water would participate in the normal photolysis process as the regular hydrogen ions from regular water. The fate of the radioactive hydrogen ions would depend on the specific experimental conditions and the subsequent biochemical reactions occurring within the plant's cells.