At stumps, Karnataka were 163 for six in reply, with left-hander Shishir Bhavane unbeaten on 55.
He added 63 runs for the unbroken seventh-wicket stand with debutant Jagadeesha Suchith (batting 14).
Bangladesh skipper Mominul Haque called correctly at the toss but his players could not repay the faith he had in his players as they were all out in 38.4 overs.
It was 19-year-old Krishna who was an unlikely hero in the absence of senior pros like R Vinay Kumar and Abhimanyu Mithun, who were rested keeping the upcoming Ranji Trophy opener in mind.
Krishna shared the new ball at the Gangotri Glades ground with H S Shararth and wreaked havoc.
Four of his five wickets were those of international players Anamul Haque Bijoy (5) who was cleaned up, Rony Talukdar (0) caught in the slip cordon. Ditto for Mominul (0) and Soumya Sarkar (1) who also could not cope with the seam movement as Bangladesh were in trouble at 27 for four. It became 41 for five when Krishna dismissed the seasoned Nasir Hossain, caught by ‘keeper CM Gautham, to get his fourth victim.
But Litton Das, with a run-a-ball 50, and Shuvagato Hom (55) gave the innings a semblance of respectability.
Brief scores:
Bangladesh ‘A’: 158 in 38.4 overs (Litton Das 50, Shuvagato Hom 55, Krishna 5-49).
Karnataka: 163-6 (Shishir Bhavane 55, Shuvagato Hom 3-29).
Image: Litton Das
Photograph: Twitter