What happens to the level of carbon-14 in an organism after it dies?

After an organism dies, the level of carbon-14 in its tissues begins to decay. Carbon-14 is a radioactive isotope of carbon that is formed in the atmosphere and taken in by living organisms through processes like respiration and photosynthesis. While the organism is alive, there is a dynamic equilibrium where the intake of carbon-14 matches its decay. However, once the organism dies, it no longer absorbs carbon-14.

The decay of carbon-14 occurs at a known rate, characterized by its half-life of about 5,730 years, meaning that after this period, half of the original amount of carbon-14 will have transformed into nitrogen-14 due to radioactive decay. This process is what allows scientists to use carbon-14 dating to estimate the age of organic materials based on the remaining carbon-14 levels.

Thus, the correct response illustrates the fundamental biological process of radioactive decay occurring after death, causing a gradual decrease in carbon-14 levels over time.