<p>1) You'll have to be more specific. Which programs, which field(s), MA/Ph.D, etc. Acceptance rates can be anywhere from the single digits to 30%+.</p>
<p>2) The general consensus seems to be that they do, but those grades don't carry <em>as much</em> weight. In other words, it's always best to aim for higher grades even outside your major. A freshman year B- in geology won't kill your chances of a Ph.D in history with a high major GPA.</p>