How does impeachment show the concept of checks and balances and
separation of powers?

The President in the executive branch can veto a law, but the legislative branch can override that veto with enough votes. The legislative branch has the power to approve Presidential nominations, control the budget, and can impeach the President and remove him or her from office.

Explanation:

food chain i would say only because there is competition on getting food and survival

travels along an axon. this triggers a wave of electrical activity that passes from the cell body along the length of the axon to the synapse