SATURDAY SCIENCE SATURDAYS: "BIOLOGY DAY," with hands-on fun, science demos, interactive exhibits and more, at Science Museum of Virginia. 864-1400. SATURDAY, TOO VIRGINIA BEER FESTIVAL Brews, food and bluegrass at Capital Ale House-Innsbrook. 780-2537, ext. 2. THURSDAY-JULY 12 KINGS FEST Christian pop performers at Kings Dominion, Doswell. 876-5561. JULY 11 CHRIS ROCK Superstar comedian at Landmark Theater. 646-4213. ALSO JULY 11ANI DIFRANCO Alt-folk singer at The National. 612-1900.