Wow, what a nice question.
Yes Joanna did read that certain perfume esters would agitate bees.
Answer:
A radioactive (unstable) phosphorus isotope is made to replace a nonradioactive isotope of phosphorus in the molecule
Explanation:
Phosphorus has both unstable (radioactive) and stable isotopes. In any compound that contains phosphorus, the phosphorus atom present may be either a stable isotope of phosphorus or an unstable isotope of phosphorus.
However, if the molecule contains a stable nonradioactive isotope of phosphorus, it is possible to convert this isotope in the molecule to the unstable radioactive isotope by carefully carrying out exchange reactions in which the phosphorus isotope replaces the nonradioactive isotope in the molecule.
This is usually done in order to create radioactive tracers which are used to study chemical reactions and biochemical processes.
Answer:
According to the law of conservation of matter, matter is never created or destroyed but it can change from one form to another. Most of the biomass in a food web gets converted at each trophic level and it no longer remains apart of the food web. Most of the biomass is released into the atmosphere in the form of heat and hence cannot be transferred to the other trophic level. Also, matter is used up by the organism itself and converted into different forms. Most of the matter might get accumulated in the soil when the organisms of a trophic level die.