Aresearcher performed an experiment in which he exposed young corn plants to a harmless, radioactive form of carbon dioxide gas containing carbon-14 instead of carbon-12. he then began feeding corn produced by the plants to a small group of goats. after several weeks, the researchers took blood and tissue samples from the goats. he was able to detect increased concentrations of carbon-14 in the goats' lipids, proteins, carbohydrates, and dna