Colin Kaepernick, the quarterback attempting to lead the San Francisco 49ers back to the Super Bowl, cut the figure of a little brother, playful and carefree as his club conducted the serious business Sunday of reaching its third consecutive NFC title game.

With roadrunner speed and a shotgun right arm, Kaepernick’s athletic trimmings drive defenses mad. The Green Bay Packers and Carolina Panthers, already victims this postseason, can attest.

With a baseball cap tilted backward and headphones the size of hockey pucks dangling from his neck, Kaepernick’s impishness is as refreshing as his style of play.

He opened a press conference following Sunday’s 23-10 victory over the Panthers by describing the afternoon’s touchdown celebration -- which mocked his quarterback counterpart Cam Newton -- as a “shout out.” He grinned and snickered. He mischievously grabbed a reporter’s pen and pad and tossed Anquan Boldin, who had caught eight of Kaepernick’s passes, a question that elicited giggles. Instead of jotting down Boldin’s answer, Kaepernick wrote, “NICE SHOES.”

Kaepernick’s boyishness is fitting: At 26, he has started 28 NFL games. But to think he doesn’t take his responsibility as conductor of the 49ers offense seriously would be a mistake. Like his team, runner-up in last season’s NFL title race, Kaepernick approached this postseason with a chip on his shoulder.

“I’m not just going to let you say anything you want to me,” Kaepernick said. “If you are going to say something to me, I am going to respond.”

Right tackle Anthony Davis, the Piscataway native and former Rutgers standout on the offensive line that protects Kaepernick, described the mentality: “The playoffs will make us show more of what we’re capable of.”

While Kaepernick is undoubtedly still growing into the position, he has demonstrated layers of maturity during these playoffs. Against the Packers in the wild-card round, he recognized running lanes adeptly, scrambling out of the backfield seven times to gain 98 yards. Kaepernick is already fifth in NFL history among quarterbacks with 377 rushing yards in the postseason.

Greg Roman, coordinator of the 49ers offense, asked his quarterback last weekend to take a more measured approach. The 49ers would attack the Panthers defense through the air. Kaepernick was to stay in the pocket and zip passes to receivers.