What is the primary characteristic of a neurotoxin?

A neurotoxin is primarily characterized by its harmful effects on nerve cells. These substances interfere with the normal functioning of the nervous system, which can lead to various physiological effects, such as paralysis, convulsions, or even death, depending on the level of exposure and the organism affected. Neurotoxins can affect both human and animal health, as well as ecosystems in general.

Understanding that a neurotoxin's action is centered on damaging nerve cells clarifies why the other options do not fit this definition. For instance, a neurotoxin does not contribute to plant growth, nor does it interact solely with plants; rather, its primary target is the nervous system of animals, including humans. Lastly, claiming that a neurotoxin has no effect on living organisms contradicts the very definition of what a neurotoxin does, emphasizing its significant and often deleterious impact on nerve cells and overall health.