The 21-year-old scored twice in the space of four first-half minutes in an opening period completely dominated by the hosts at the Estadio do Rio Ave Futebol Clube.
Ukra then made sure of the points in the second half to help Pedro Martins' men leap-frog Sporting Lisbon into seventh in the table, while the visitors remain just four points above the drop zone.
Rio looked the livelier of the two sides in the opening exchanges and Tarantini saw claims for a penalty waved away when he went to ground in the area, the referee opting to book the midfielder for simulation.
The opener deservedly came in the 36th minute when Koka side-footed home at the back post from a deep free-kick from the right-hand side, before he soon doubled the lead when he swept home Tiago Pinto's excellent throughball.
Academica improved after the break and Nwankwo Obiora should have done better when he prodded straight at Rio goalkeeper Cassio when the ball fell kindly for him in the six-yard box.
The visitors failure to hit the target then proved costly in the 65th minute when Ukra raced free on goal and kept his composure to clinically place his shot in the bottom left-hand corner to secure the points for the hosts.