iMac 2012 and UPS

Have a late 2012 iMac 21.5 inch with OSX 10.9.4 connected to a UPS from APC ES-750 configured to shut down the iMac once UPS gets to 50% battery remaining.

The question is: if the iMac is in sleep mode and there is a power outage, will the iMac know to shut down?

Thanks for any input.