7__ (a) An post-synaptic potential is stimulated at the postsynaptic membrane and impulse travels down dendrite towards axon hillock. 2 __6___ (b) An enzyme cleaves the neurotransmitter substance and clears out the synaptic cleft. 3 ___1__ (c) Action potential reaches end of axon. 4 ___4__ (d) Impulse stimulates synaptic vesicles to move to presynaptic membrane. 5 ___2__ (e) Neurotransmitter substance diffuses across the cleft. 6 ___3__ (f) Neurotransmitter substance fits into receptor sites on postsynaptic membrane.

Ascientist is investigating the effects of salinity on fish development. he places fertilized fish eggs in an aquarium that contains low salinity and observes their development. what factor would improve experimental design the most? place the fish eggs in the open ocean because that is the natural habitat include another aquarium that has normal salinity to compare to the low salinity aquarium include an aquarium that replaces salt with sugar to confirm that the effects are specific to salt grow algae with the fish eggs in order to provide adequate nutrients to the developing embryos