The principle of "Separation of Powers" is improved with a bicameral legislature rather than a unicameral legislature because a bicameral legislature:

Responses

requires that two bodies of government pass laws
requires that two bodies of government pass laws

takes more of the power from the executive branch.
takes more of the power from the executive branch.

creates a legislature that has less power than the judicial branch.
creates a legislature that has less power than the judicial branch.

works with the local level in order to achieve that two-house structure.
works with the local level in order to achieve that two-house structure.

requires that both houses agree on a bill before it becomes law.