All living things absorb carbon from the atmosphere, including an amount of radioactive carbon-14. It is mostly found in atmospheric carbon dioxide because that is where it is constantly being produced by collisions between nitrogen atoms and cosmic rays.

Is carbon-14 present in all living organisms?

This tiny ratio exists in all molecules involving carbon atms, including all living matter. This is why carbon 14, along with potassium 40, accounts for almost all the natural radioactivity of our body.

How does carbon-14 get into a living thing?

Carbon-14 formed in the atmosphere can combine with oxygen to form carbon dioxide (CO2). This carbon-14 labeled carbon dioxide is taken up by plants in their normal process of photosynthesis. Animals and people that eat these plants take the carbon-14 into their bodies as well.

How is carbon-14 used in biology?

The carbon-14 nucleus has six protons and eight neutrons, for an atomic mass of 14. The isotope also is used as a tracer in following the course of particular carbon atoms through chemical or biological transformations. Carbon-14 present in molecules of atmospheric carbon dioxide enters the biological carbon cycle.