Ireland sevens international Heffernan earns inclusion in the matchday 23 after impressing for the Wolfhounds in the Celtic Challenge.
Bemand has stuck with a front row of Linda Djougang, Neve Jones and Christy Haney, while Aoife Walker, Edel McMahon and Brittany Hogan are retained in the back row.
Deely earns her first start of this year’s tournament in the back three alongside wings Katie Corrigan and Beibhinn Parsons.
The Irish are coming off a crushing 88-10 defeat by England at Twickenham having earned their first Six Nations wins since 2022 against Wales in Cork.
However, Bemand’s side could still finish third – and secure World Cup qualification – with victory over Scotland, who are currently third, at Kingspan Stadium on Saturday.
“Last week was tough but we’ve seen great bounce back in training,” said Bemand.
“This weekend, the Six Nations reaches its climax and with some good performances, we’re in a position to compete for that World Cup qualification.”
Ireland: Deely; Corrigan, Higgins, Breen, Parsons; O’Brien, Reilly; Djougang, Jones, Haney; Wall, Monaghan (co-capt); Wafer, McMahon (co-capt), Hogan.
Replacements: Moloney, O’Dowd, McGrath, Tuite, Ikahihifo, Scuffil-McCabe, Dalton, Heffernan.