Biology
The Role of Isotopes in Tracing Metabolic Pathways
Quick fact
In the 1940s, Melvin Calvin used carbon-14 to trace the path of carbon in photosynthesis, revealing the Calvin cycle and earning a Nobel Prize in 1961.
Why this is interesting
How do scientists know what happens to the food you eat—step by step, inside your cells? They use invisible tags called isotopes to trace every single atom's journey.