I'm not yet an undergrad, but I'm curious as to the difference between grad vs undergrad admissions (specifically for sciences; also, I'm not asking so that I can spend my time as an undergrad trying to impress grad schools, just out of curiosity). As an undergrad, you have a lot more access to research than a high schooler (most of the time), but there are fewer competitions to win and such, so is research looked at more? Would professor recommendations valued a lot more because they are coming from professional scientists (or writers or historians etc.)? Is it as competitive? Are "good" undergrads expected to do anything particular?