Lets be real. Business is business. There is nothing immoral about being a smart applicant and a wise negotiator, whether it be for jobs and salary/benefit packages or used car prices. We all try to put forth our best/most impressive sides for medical school applications and interviews, while playing down the things that make us look less then stellar. After all, why disclose all those wild keg parties in college and that string of one-night stands in Amsterdam? Instead, one discusses being able to successfully maintain an active social life in college while focusing on academics and also having had the opportunity to travel and get to explore another culture abroad. See what I mean. One would be crazy to slit one's own throat by needlessly disclosing things that need not be disclosed.
In the case of the OP applying for a job, there is no requirement to disclose specific future plans and timelines, especially since many things can change over the course of a year. There is no gaurantee of a medical school acceptance, and therefore no way to really say that employment will only be restricted to a year. It is true that you are considering pursuing additional graduate education in the future, so you can easily say that if asked. Actually, you can even start to change the subject a little by following up in asking them about any company incentives for education, or even additional training and advancement opportunities through the department in which you are working. Even if you think you will be gone in a year, you may end up still being there, so these things should still be of interest to you.
There are also comments like: "Well, it is true that I have considered pursuing additional educational opportunities in the future, but at this point I am focused on developing my skills in (whatever the job involves, relevant field, whatever) because I feel that it would be a good fit for me and I believe that I would prove to be a valuable asset to your team."
Where do you see yourself in 5,10,20 years? You should start getting comfortable with this question if you arn't already. No one really knows where they will be in 10 years, but you can definitely give a good well-rounded semi-generic answer with some specifics tailored to whatever your particular situation is. What you don't want to say is that in 10 years you see yourself finishing a fellowship in cardiology. Kinda makes that hypothetical insurance management, lab, or whatever position you are applying for look like a terrible fit for you. When in actuality, the job you are applying for is probably a good fit to meet your needs right now, and potentially for some time in the future as well if your plans change or things don't work out.
The bottom line is that it is important to have strong morals and a good work ethic. However, it is also important to be a smart professional and keep an eye out for yourself and your own needs. The company's primary focus is to do what is best for the company, as it should be. You should respect the company's needs and be a loyal employee, but your main priority should be to plan for yourself and your family. The corporate world sure isn't going to do it for you.