Describe briefly with the help of a circuit diagram, how the flow of current carries in a p-n-p transistor is regulated with emitter-base junction forward biased and base-collector junction reverse biased. 

The emitter-base junction is given a small forward bias, while base collector junction is given a large reverse bias.
Under the forward biasing of emitter-base region, the positive holes of P - region move towards the base. Due to thin base most of holes (about 98%) entering it pass onto collector while a very few of them (nearly 2%) combine with the electrons of base.
As soon as a hole combines with the electron, a fresh electron leaves the negative terminal of battery V_EE and enters the base. This causes a very small base current I _B. The holes entering the collector move under the aiding reverse bias towards terminal C. As a hole reaches terminal C, an electron leaves the negative terminal of battery V_CC and neutralizes the hole.
This causes the collector current I_C . Both these currents I_B and I_C combine to form the emitter current I_e.

i. e., I_E = I_B + I_C
Obviously the holes are the charge carriers within the p-n-p transistor while the electrons are charge carriers in external circuit.