Two specific examples of radioactive isotopes being used as “spies”

Carbon-14  in photosynthesis and Florbetapir (18F) in PIB of Alzheimer's disease.

Explanation:

These radioactive isotopes known as the biological spies as they tell or mark the presence or activity of a particular atom to the scientists in living beings.

For instance,

1. the process of photosynthesis can be understood by observing the radioactive isotope Carbon-14 from taking the carbon dioxide to the generation of glucose molecule by molecule process.

2. A protein that is deposited in people with Alzheimer's disease, called beta-amyloid. It is bind with another protein known as PIB, which contains  Florbetapir (18F) a radioactive isotope. It gives an idea about the location of PIB and deposits in amyloid to try to eliminate the protein deposits and check the effect of medication.

answer; i believe the answer is (polygenic inheritance;