How does one determain if an ecosysten is in "balance"

An ecosystem is said to be balanced when gases are in their correct proportions. Also when there is enough preys for the amount of predators and generally there should be fewer large organisms than there are small ones.

Neurotransmitters are messengers responsible for communication between neurons. they are released from synaptic vesicles and are received by receptors.  the communication is referred to as neurotransmission. the following statement is true about neurotransmitters: a. they're stored in synaptic vesicles in the axon.