how google penalized backlinks
 

will sudden increase in backlinks result in google penalty?

Google set some guildelines about quality backlinks as well as quality content. If your website backlinks or content going to be against the google guidliness then Google penelize your website backlinks. And if you have so many backlinks which was penelize by google then your website also penelize by google.

SEO_butterfly is correct. The amount of backlinks is never penalized. The quality of the backlinks can bring penalties. If you are on a adult website with a backlink and have it linked to a Restaurants website, Google doesn't see that as legitimate. If you buy backlinks through a online company and Google knows those companies and their sites, and your backlinks wind up on "flagged" sites. You definitely will be penalized.

Yes, if they are in bulk, and are coming from low quality and irrelevant websites then Google definitely penalize that website.