My laptop BIOS is password protected. Probably the password can be bypassed using some hardware and software means. But is it possible that somebody having access to laptop but not knowing the password can bypass it without me knowing it when I log on at a later stage ? I am trying to protect my laptop from malware / spyware. I am concerned about spying. Since important folders are encrypted, I am not worried about data theft. Attacker may have 10-12 hours of time.
Yes it's possible.
BIOS passwords are not usually taken seriously by manufacturers as a meaningful security measure on their own, since most people don't take care to secure their systems physically. Instead it's expected to act as a deterrent in cases where physical accessibility is reduced, such as public access terminals in schools or offices, to prevent users from tampering with settings that could case maintainers a headache.
if an attacker can get hold of your device he could apply hardware debugging techniques to extract your current password, or as is much more likely, install a keylogger and wait for you to enter the password for him.
If you want to secure your device against attackers bypassing the BIOS password, you should lock it away in a tamper proof hard case, which will allow you to determine if an attacker has had physical access to the device.