The radioactive isotopes are the elements that exhibit unstable and heavy nuclei. The isotopes disintegrate or decay by fission to form entities that exhibit stable nuclei. The radioactive elements are the parent atoms which disintegrate into daughter products and subatomic particles. This disintegration process liberates a lot of energy in the form of radiation like gamma rays. Hence, the type of radiation emitted by the disintegration or decay process of the radioactive isotopes can be useful to detect their elemental type and their origin.
The organism is bacteria because it performs photosynthesis and can propel itself with flagella. It is not an animal because it can photosynthesize and it is not a plant because it has flagella like bacteria does.
