By Daniel Chavkin The Cowboys will turn to their third quarterback of the year vs. Iowa State. Gunnar Gundy, the son of Oklahoma State coach Mike Gundy, will start for the Cowboys vs. Iowa State on Saturday, Brett McMurphy reports. This will be Gundy’s first start in his college career. Oklahoma State starting quarterback Spencer Sanders injured his shoulder two weeks ago vs. Kansas State. Last week, backup quarterback Garrett Rangel got the start in a loss vs. Kansas, but this week, it will likely be Gundy instead. On the season, Gundy has played in three games, completing 14 passes for 144 y…