In all likelihood, the interviewer will actually speak with your former employer so honesty is key. Answer as confidently and positively as possible and list all of the positive things your past employer would recognize about you. Do not make the mistake of simply saying you are responsible, organized, and dependable. Instead, include traits that are directly related to your work as a medical assistant, such as the ability to handle stressful situations and difficult patients, the way you kept meticulous records, and more.