Gow won and converted the spot-kick after being felled by Gulls right-back Joe Oastler.
The hosts had taken a 15th-minute lead through 12-goal top-scorer Rene Howe after Grecians midfielder Tommy Doherty was adjudged to have handled Nathan Craig's deep cross.
Tisdale said: "Alan Gow was fantastic for us. As he proved he is a very good player if you get the ball to him. He did a great job.
"We lost John O'Flynn after five minutes to injury and Jamie Cureton is suspended so we had no recognisable number nine out there, no out-and-out striker, so it was left to Alan Gow to come on and lead the line.
"He played very well, I thought we played very well as a team in the second half."