MOSFET saturation case?
Take a look at how the MOSFET conducts. Essentially, as you add the gate voltage, you are accumulating more and more holes to aid in the conduction. Less voltage means less holes, but never 0. This is important in that there will always be SOME conduction, but the construction of the MOSFET plays a huge role in how much is allowed through. Subsequently, adding a large voltage all of a sudden means more holes. Assuming you haven't destroyed the device, the conduction again depends on construction.