Achievement and proficiency in subject matter include your realization that neither is to be achieved by cheating.  An instructor has the right to give you an F on a single assignment produced by cheating without determining whether you have a passing knowledge of the relevant factual material.  That is an appropriate academic evaluation for a failure to understand or abide by the basic rules of academic study and inquiry.  An instructor has the right to assign a final grade of F for the course if you plagiarized a paper for a portion of the course, even if you have successfully and, presumably, honestly passed the remaining portion of the course.  It must be understood that any student who knowingly aids in plagiarism or other cheating, e.g., allowing another student to copy a paper or examination question, is as guilty as the cheating student.

plagiarize, v. 1) To steal and use (the ideas or writings) of another) as one's own (from the American Heritage Dictionary)
cheat, v. 1) To act dishonestly; practice fraud (from the American Heritage Dictionary)

If you turn in someone else's work as if it were your own, you are guilty of cheating.  This includes homework sets, answers on exams, project reports, etc. If you use the assistance of another student in taking an exam or quiz, that is cheating. If you use material from another source verbatum without quoting and attributing that source, that is plagarism.

Anyone who asks you to cheat is threatening your grade and your future as well as his or hers.  Don't give in!