Symptoms of schizophrenia refer to "excess" behaviors, such as hallucinations, whereas symptoms refer to "deficits", such as flattened emotions or loss of activity. alpha; beta type a; type b hyperactive; hypoactive positive; negative

Excess receptors for Dopamine are found in schizophrenics. Thereafter, the first blank is positive.  Lower levels of Monoamines leads to flattened emotions or loss of activity, or negative.

Answer is D.

yes, since there is a positive and a negetive if the positive and negitive wasn't there wouldn't a flow electricity in it.

the invasive species was introduced due to commercial purpouses, as there was a demand for fur clothes and hence, a business opportunity connected to this product. actually, it was when the nutrias scaped, causing harm to the us ecosystems when they acquired the status of invasive species. in this case they have caused an environmental problem, but it could have affected also economic interests or even human health.