Probably not, if the rear derailleur is a 105 ss (10 spd 5700) then max sprocket size is 28t on both the ss and gs rear derailleur (info sourced from Shimano website)
If you want to run a really low gear for hill climbing then the new 5800 11spd 105 gs rear derailleur will run up to a 32t sprocket, but be careful if you're thinking of doing upgrades, 10spd and 11spd shimano components are not usually cross compatible. (ie. you can't use an 11spd rear mech with 10spd STi's or vice versa)