Tina Drummond, age 15, of Portland, Ore., for her question:

WHAT IS A BICAMERAL SYSTEM?

A bicameral system is a legislative system in which the power of making the law is vested in two chambers, or houses, both of which must approve a bill before it becomes law.

In general, the upper house is composed of members selected on a territorial basis, representing states or other political subdivisions rather than the people directly. Usually they serve longer terms than the members of the lower house. In theory, the upper house provides the legislative experience necessary to control unwise legislation. The lower house is generally composed of members selected on the basis of population, each member representing an equal number of citizens. Usually they reflect more strongly the contemporary mind of the electorate.

Typical of the bicameral system is the United States Congress, which consists of a Senate, constituting an upper house, and a House of Representatives, constituting a lower house.

The bicameral system is in force in all states except, since 1937, Nebraska, which has a unicameral, or single chamber, legislature.

Throughout the world national parliaments are about equally divided between bicameral and unicameral systems.