Question

If plants are grown for several days in an atmosphere containing 14CO₂ instead of 12CO₂, one would expect to find?

Answer 1

Plants fix atmospheric carbon dioxide during photosynthesis, leading to a match in the fraction of 14C in the plant tissue and the atmosphere. After the plant dies, the concentration of 14C declines due to radioactive decay.

Step-by-step explanation:

When plants fix atmospheric carbon dioxide (CO₂) into organic compounds during photosynthesis, the resulting fraction of the isotope 14C in the plant tissue will match the fraction of the isotope in the atmosphere. After a plant dies, the incorporation of all carbon isotopes, including 14C, stops and the concentration of 14C declines due to the radioactive decay of 14C following 14 C → ¹4N + e+.