At times during his weekly news conference, 49ers head coach Kyle Shanahan wore a sly grin as he fielded a stream of questions about his new quarterback, Jimmy Garoppolo. Shanahan didn’t seem to mind one bit. One day after Garoppolo’s triumphant debut as San Francisco’s starter, Shanahan turned the obvious into the official. Garoppolo will start again Sunday, when the 49ers (2-10) meet the Texans (4-8) in Houston. Even if his inaugural start wasn’t always artistic — the 49ers didn’t score any touchdowns in their 15-14 victory over Chicago — Garoppolo is injecting welcome excitement into an otherwise desultory season. Shanahan essentially acknowledged this in talking about reviewing video of Sunday’s game. “It was fun to watch,” he said Monday. “You could tell Jimmy made some impressive throws. There were definitely situations where he got a little confused, and he still was able to make plays. It was very impressive to keep his poise and make some plays when things weren’t perfect.” Garoppolo completed 26 of 37 passes for 293 yards against the Bears, with one interception. His ability to improvise, as Shanahan suggested, will serve him well at a position where improvisation is part of the job requirement.