The medication would be the controlled variable, the factor that remains constant.
You would want this observation to be in an area with a lot of biotic and abiotic factors, so the best place for it is an ecosystem.
Lymphoid organs in the immune system, includes the bone marrow
Explanation:
What would cause a tree to die?
There are 5 factors to which a tree eventually succumbs: death from its environment, death from harmful insects and diseases, death from a catastrophic event, death from age-related collapse (starvation) and of course, death from harvest.
I hope this helps
