was the above mentioned song performed live ?
Yes, a number of times.
What Makes You Beautiful
One Direction performed "What Makes You Beautiful" for the first time on "Red or Black?" on 10 September 2011. 
who sings what in what makes you beautiful The band - One Direction who are the members of this band ? Niall Horan, Liam Payne, Harry Styles and Louis Tomlinson. Zayn Malik was a former member.
wiki:856505
What Makes You Beautiful [SEP] Live performances
One Direction performed "What Makes You Beautiful" for the first time on "Red or Black?" on 10 September 2011. The performance started with hosts Ant & Dec announcing that the band was supposedly running late for their appearance, and cut to a video of One Direction boarding a London Tube carriage full of fans, as the studio version of the song began playing. Each fan on the tube was given a numbered ticket. The band and fans disembarked the tube and made their way to the television studio, where the remainder of the song was sung live. After the song, Styles caught a numbered ticket raining onstage.