San Francisco quarterback Brock Purdy, after missing one game because of an ailing right shoulder, will start for the 49ers on Sunday night against the host Buffalo Bills.Purdy was listed as questionable after being limited at practice Wednesday and Thursday but was a full participant on Friday and on the active list Sunday.He was injured in the loss to the Seattle Seahawks on Nov. 17 and sat out the 38-10 loss last Sunday at Green Bay as the 49ers fell to 5-6.”If I’m out there playing, which is the plan, then I’ll be able to make every throw that we have drawn up,” Purdy, 24, said on Friday. “I wouldn’t go out there and play not (at) 100 percent. I want to go out there feeling really good and have the confidence to make every throw, so that’s the plan.”Purdy is 202-for-306 passing this season for 2,613 yards, 13 touchdowns and eight interceptions in 10 games (all starts).He won’t have protection from starting left tackle Trent Williams (ankle) and left guard Aaron Banks (concussion), who are inactive. Their spots likely will be filled by linemen Ben Bartch and Jaylon Moore.