Human for certain. And, for many people, that also includes animals.
Polonium isotopes are not used as tracers.
no they should not
No. You should never taste anything used in any kind of an experiment for any reason.
NO
not sterile
You should have everything set out correctly.Which means you should have the notebook your going to make observations with and have your safety tools.
An experiment is an example of an exercise.
I.What types of plants were used in the experiment?II.What was the experiment's control? III.Was the experiment repeated more than once?
Constants are factors in an experiment that stay the same. This should not be confused with controls -- which is a standard used for comparison
Control
which experiment