In normal case, emitter-base junction is forward bias and collector-base junction is reverse biased. What will happen if emitter is reverse biased and collector is forward biased?
If emitter is reverse biased and collector is forward biased, then emitter works as collector and collector works as emitter. In such situation, transistor works but has lower amplification because the size of emitter is smaller than collector and doping of emitter is more than collector.