Two of the personnel changes are in the forwards, with Jason Harris-Wright coming in at hooker instead of Stephen Douglas and James Sandford replacing David Nolan. Nolan and Douglas are named amongst the replacements where the final change to the squad sees Kris Greene replaced by Ian Porter.
Scrum half Greene suffered a bad injury in training and will be unavailable for the rest of the season.
The positional switch is in the back three, with David Kearney and Shane Scanlon swapping positions. Kearney moves to full-back from the right wing and Scanlon takes over in the number 14 jersey.
Ireland coach Eric Elwood said: "The game against France was another notch up with regards to the level of performance. But in the end it just got away from us after the guys battled hard to get back into the game against what was a very good French side.
"We have made some changes to the side as both Jason (Harris-Wright) and James (Sandford) played well when they came off the bench and have forced themselves into the team on the back of that. There was a great attitude from the team when we got back together this week and we are looking forward to the game and getting back home to Dubarry Park.
"The challenge for us is to again raise our performance levels if we want to get a positive result against a good Scotland side who, although they lost their first two games, have been highly competitive in both of them."
IRELAND UNDER-20 TEAM & REPLACEMENTS (v Scotland Under-20s, RBS U-20 Six Nations, Dubarry Park, Athlone, Friday, February 22, kick-off 7.30pm):
15 - David Kearney (Lansdowne/Leinster)
14 - Sean Scanlon (UCC/Munster)
13 - Eoin O'Malley (Old Belvedere/Leinster)
12 - Eamonn Sheridan (Lansdowne/Leinster)
11 - Chris Cochrane (Queen's University/Ulster)
10 - Martin Dufficy (Dublin University/Leinster)
9 - David Moore (Blackrock College/Leinster)
1 - Paul Karayiannis (Queen's University/Ulster)
2 - Jason Harris-Wright (Greystones/Leinster)
3 - Ben Barclay (UCD/Leinster)
4 - James Sandford (Queen's University/Ulster)
5 - Eoin Sheriff (Lansdowne/Leinster)
6 - Kieran Essex (UL Bohemians/Munster)
7 - Paul Ryan (Blackrock College/Leinster) (capt)
8 - Patrick Mallon (Lansdowne/Leinster)
16 - Stephen Douglas (Ballymena/Ulster)
17 - Stephen Archer (UCC/Munster)
18 - David Nolan (Galwegians/Connacht)
19 - Ian Nagle (UCC/Munster)
20 - Ian Porter (Queen's University/Ulster)
21 - Ian Madigan (Blackrock College/Leinster)
22 - Conor Cleary (Greystones/Leinster)
Manager - Phil Orr
Coach - Eric Elwood
Assistant Coach - Dan McFarland
Ireland U-20s v Scotland U-20s, Friday, February 22, Dubarry Park, Athlone, kick-off 7.30pm
Ireland U-20s v Wales U-20s, Friday, March 7, Dubarry Park, Athlone, kick-off 7.35pm (live RTE TV)
England U-20s v Ireland U-20s, Friday, March 14, Kingsholm, Gloucester, kick-off 7.45pm