This is the time for questions.

With training camp opening Monday, it's time to determine what issues Cal needs to resolve between now and the season-opener against Michigan State on Aug. 30.

Last year at this time, Cal didn't seem to have many uncertainties. The Bears were ranked in everybody's preseason top-15 and some believed they had a chance to unseat USC for Pac-10 supremacy and qualify for a Bowl Championship Series game.

In light of Cal's up-and-down 7-6 campaign, maybe more questions should have been posed. Nobody is going to make that mistake this year.

The Bears open training camp with a slew of uncertainty. Here are the top five questions facing Cal when it takes the field at Memorial Stadium on Monday.

1. Who will be the starting quarterback? This is a story line that won't only be followed closely here in the Bay Area, but observers across the nation will be watching to see if fifth-year senior Nate Longshore can hold off redshirt sophomore Kevin Riley as the Bears' top signal-caller.

After a productive 2006, Longshore had an uneven 2007, partly because of an ankle injury that bothered him during the second half of the season. Riley dazzled in relief of Longshore in Cal's win over Air Force in the Armed Forces Bowl, and coach Jeff Tedford said the position is open. The competition never got legs in the spring after Longshore suffered a pulled pectoral muscle during the first week.

Longshore outplayed Riley, albeit ever so briefly, before suffering the injury during the spring and likely will begin camp taking reps with the starting unit. Tedford said he won't name a starter until the week of the opener, and possibly will play both players against Michigan State to get a more thorough evaluation.

"I feel like we're in a great situation with our quarterback position," Tedford said. "Obviously, Nate has played a lot of games for us and won a lot of games for us. He's a very talented guy. Kevin Riley is a guy who came in last season and had a couple of opportunities and showed very well. It's going to be a very competitive fall camp. I don't look at it as such a question. It's just a matter of making a decision on who's going to take the first snaps."

2. Have the Bears cured whatever ailed them during the second half of last season? It wasn't just that the Bears lost six of their final seven regular-season games after beginning the year 5-0 and rising to No. 2 in the national rankings. It's how they lost them. Penalties, turnovers and other assorted mistakes were the biggest culprit, and the Bears seemed to suffer from a lack of proper focus and leadership. Everyone seems to agree that the lack of leadership was issue No. 1 that had to be addressed in the offseason, and Tedford and Cal's seniors have spent the spring and summer trying to identify the leaders of the future.

"Last year, our leadership probably didn't step up as it should have because we had a lot of new leaders out there," Cal senior linebacker Worrell Williams said. "They didn't really know how to be leaders. The guys now, being a leader is kind of natural to all of us."

Williams singled out himself, fellow linebacker Zack Follett, center Alex Mack and fullback Will Ta'ufo'ou as players who have emerged as team leaders. Tedford said leaders don't necessarily need to lead fellow players in cheerleading, but address concerns and issues behind closed doors.

"Not so much rah-rah stuff, but behind the scenes in the locker room," Tedford said. "When they feel like something is going awry, to be able to step up and say, 'This is what we're about or this is what we're doing.'"

3. Do the Bears have any productive receivers? The Bears essentially have no idea what they are going to get from their new receiving corps. Gone are NFL draft picks DeSean Jackson and Lavelle Hawkins, as well as Robert Jordan. Cal has 12 total career receptions from its current wideouts — 10 by backup LaReylle Cunningham and two from transfer Nyan Boateng while he was at Florida.

Redshirt freshman Michael Calvin looked terrific on the scout team last year but his progress was slow during the spring. He and Boateng figure to be the Bears' top threats. Jeremy Ross is an athletic specimen who had a strong spring before suffering an ankle injury. Tedford has said at least one — and maybe more — of the team's heralded group of incoming freshman receivers will have a chance to play right away.

"I feel good about our talent level there, but they don't have a lot of experience," Tedford said.

4. Is sophomore Jahvid Best healthy enough to be an every-down back? Tedford declared Best 100 percent healthy after suffering a potentially serious hip injury near the end of last season. Best demonstrated the potential to be a star in limited time as a true freshman last season. Even without the injury, there were questions if Best had the size and strength to run between the tackles and assume most of the workload out of the backfield. The good news is the Bears also are high on redshirt freshman Shane Vereen, who should be able to help shoulder the burden in the running game.

"I'm very, very anxious to see these guys perform," Tedford said. "We've had some very good running backs at Cal in our tenure. This is the most explosive combination in the backfield since I've been here."

5. Will the defense improve in the new 3-4 alignment? The Bears defense ranked sixth in the Pac-10 in total defense and scoring defense last year, and the defensive line was a big problem. Given Cal's depth at linebacker, the Bears' decided to switch from a 4-3 to a 3-4 to get more of that talent on the field. The Bears also will have one less lineman on the field, and they have enough talent to fill those three positions with quality.

The Bears spent the spring putting in the system, and it was met with enthusiasm. Follett said it will allow him to play more on instinct, and he should team up with either Mike Mohamed or Eddie Young to give Cal a pretty good tandem of speedy playmakers on the outside.

"I think it will finally let our linebackers go out and make plays," Follett said. "I'm excited about the defense. It fits our personnel perfectly."

While the new scheme should give Cal some advantages, there is some sacrifice as well. The biggest concern is how the Bears will hold up against a power running team.

"Our D-linemen are going to have to step up," Follett said. "That's the biggest question so far, is how the D-linemen are going to adjust. But I think they'll do fine."