John Beattie will make his first Six Nations start this year having recently recovered from a bout of glandular fever that kept him out of all three matches so far in the championship. John Barclay returns following a head knock sustained against Wales Under-21 in Newport last month.
Coach Iain Paxton said: "This is the back row that we were hoping to have right from the start but unfortunately it wasn't possible. Hopefully they'll produce the level of performance they are capable of and we'll benefit from the experience they've gained from their pro-teams."
Also joining the two Johns in the line up are Warriors James Eddie (lock) and Iain Kennedy (centre).
Scotland Under-21 team to play Ireland in Athlone in the shadow Six Nations on Friday 10 March (7.30pm)
15 Ben Addison (Stirling County and Central Institute of Sport)
14 Cameron Johnston (Newcastle Falcons)
13 Ben Cairns (Edinburgh Gunners, Currie and Scottish Institute of Sport)
12 Iain Kennedy (Glasgow Warriors, Glasgow Hawks and West Of Scotland Institute of Sport)
11 Lee Kibble (Border Reivers, Biggar and East of Scotland Institute of Sport)
10 Dave Blair (Sale Sharks) CAPTAIN
9 Greig Laidlaw (Jed-Forest)
1 Ryan Grant (The Army)
2 Sean Crombie (Aberdeen GSFP and Grampian Institute of Sport)
3 David Young (Leicester Tigers)
4 James Eddie (Glasgow Warriors, Ayr and West Of Scotland Institute of Sport)
5 Ian Nimmo (Leicester Tigers)
6 John Barclay (Glasgow Warriors and Scottish Institute of Sport)
8 John Beattie (Glasgow Warriors and Scottish Institute of Sport)
7 Alan MacDonald (Edinburgh Gunners and Scottish Institute of Sport)
Substitutes
16 Andrew Reekie (Currie)
17 Kyle Traynor (Edinburgh Gunners, Boroughmuir and East of Scotland Institute of Sport)
18 Scott Newlands (Heriot's and East of Scotland Institute of Sport)
19 Calum Forrester (GHA and West Of Scotland Institute of Sport)
20 Stephen Biggart (Glasgow Hawks)
21 James King (Border Reivers, Melrose and East of Scotland Institute of Sport)
22 Chris Dunlop (Durham University)