The hosts took the lead in the eighth minute when Currie centre Cameron Hutchison went over for a try and it was converted by stand-off Josh Henderson.
Ireland stand-off Johnny McPhillips then kicked two penalties to make it 7-6.
Two penalties from Glasgow Hawks’ Henderson then made sure that Scotland led 13-6 at the interval.
Ireland levelled the scores in the 43rd minute before Henderson kicked two penalties to put Scotland 19-13 ahead.
Ireland went 20-19 up with a converted try by second-row Fineen Wycherley. Henderson had a chance to win it, but his penalty slipped wide.