Real answer, not entirely. The rudder primarily controls the yaw of the aircraft. While in the air, it can help smooth out turns and such for the comfort of the passengers. Though you could fly just fine using the ailerons to bank the aircraft. While you can affect the yaw with the ailerons, they also roll the aircraft so the wings aren’t level. This becomes an issue when you need to make small adjustments during takeoff and landing when you need the wings to be level (and in turn the landing gear will be level).