Unnatural occurrences can have the most significant impact on an ecosystem. true

True

Explanation:

Unnatural occurences are those catastrophic events induced by humans which can exert drastic impact over the ecosystem. These may include deforestation, forest fire, intentional explosion, and others. This will result in loss of many species due to damage caused to the non-living physical environment.

after receiving a stimus, the sensory receptors send(s) signals to the appropriate area of the body.  

the must be sensory neurons.  

hope its .