Texas Instruments Product Engineer & Applications Engineer interview questions

What is the difference between a bjt and a mosfet? Bjt has "leakage current" in the gate, however I said mosfet has infinite gate resistance and bjt has rpi as the base resistance, this was considered incorrect. What does this digital circuit do? It was a DFF with Q* plugged into D, and Q is output. It was a frequency divide by two system. How to make sure voltage from first system gets to second system? First system is plugged into base of bjt and collector is plugged into second system. The answer was to add a pull up resistance which is vdd in series with resistor, connected to collector. I gave plenty of working answers, but none were considered correct.