transistor has only two PN-junction .
base-Emitter junction and Base- collector jumction .
there is no PN junction between emitter and collector.
transistor can be represented by diode equivalent cct.
to use transistor as a amplifier its base emitter junction is forward biased and base collector junction is reversed biased. now how the base collector is reverse biased .
A PN junction is said to be forward biased when anode is at 0.7v higher then cathode.
now look at ur diagram .
collector bias voltages(VCC) are at higher potential then base voltage so cathode of base-collector junction is at higher potenial then anode so this junction is reverse biased.
hope u got it…