The benefit of using Aplysia to study the neural and biochemical processes that allow for classical conditioning in simple organisms is that:

explanation:

b,bacteria convert nitrates

into nitrogen gas.

d,plants and animals take in

and use nitrogen compounds.

e,bacteria break down waste    

products and return nitrogen  

to the soil.

a,bacteria convert atmospheric

nitrogen to ammonia.

c,bacteria convert ammonia

to nitrites and nitrates.

i guess because there isn't enough love going around. < 3