Employers hiring medical assistants are looking for candidates with a mastery of both clerical and interpersonal skills. Expect to be quizzed on health care procedures as well as experience tending to patient needs. You may be asked to answer role-play question that will test your ability to handle difficult patients in a sympathetic and professional way. Be aware that many employers will expect candidates to be certified by the American Association of Medical Assistants.
"What would you do if a scientist asked you to do something that wasn't in your job description?"
Focus on safety - if the task was safe for you to carry out (e.g. not being asked to place your hand in moving machinary) and if you would be allowed to carry out that task at your position i.e if it was a task that only a registered scientist could carry out then you should point that out to them.