Would biceps femoris be paralyzed if the sciatic nerve was severed?

The answer is no.

The sciatic nerve is a large nerve that runs from the lower back down the back of the thigh. It branches into two nerves, the tibial nerve and the common fibular nerve. The tibial nerve innervates the muscles of the calf and the sole of the foot. The common fibular nerve innervates the muscles of the front of the thigh and the lateral side of the leg.

The biceps femoris is a muscle located on the back of the thigh. It is innervated by the common fibular nerve. Therefore, if the sciatic nerve was severed, the biceps femoris would not be paralyzed.