Suppose a particular neurotransmitter causes an ipsp in postsynaptic cell x and an epsp in postsynaptic cell y. A likely explanation is that

This situation states that the cells has two different receptors on them.

Explanation:

The particular neurotransmitter can have different receptors on them. An (EPSN) excitatory postsynaptic potential causes change in the membrane potential of the postsynaptic cell which tends to open the channels for the positively charged ions inside the cell.

This leads to the activation of the ligand sensitive channels.

In case of the inhibitory postsynaptic potential ( IPSP) makes the neurons less like to generate any action potential.

So, for the same neurotransmitter, one cell X shows excitatory response and other cell y shows inhibitory response.

ADAPTATION

People in living in areas with steep mountains actually has an advantage when it comes to agriculture because there is already a free and vacant space that can be used to plant crops. In order to develop thesemountains into an area where planting is easily done, the people can create a stair-like structure on the edges of the mountains where they can plant crops that will be used daily and even sold in the market. This practice will be a very good strategy to make use of the steep mountain which is the only available natural resource at the time.