Mistakes belong to every job–even if health is at risk. It is impossible to live, and to work, without ever making a mistake.
Interviewers try to find out if you can admit making a mistake, if you look at it responsibly, and if you learned a lesson from mistakes you have made in the past (either in your job, or in your personal life).
You should not say that you do not remember mistakes. Even if you made only small mistakes, pick one of them for your answer.
And if this is your first job application, refer to mistakes you made during your MA practice, or even a mistake from your personal life. Your attitude to mistakes is more important than the particular situation you decide to narrate in an interview. See sample answers below.
Once I completed a wrong insurance form, and the insurance company did not pay us. I made the manager angry, but I learned from my mistake, I and never repeated it again, always double checking the form.
I mixed medical records of two patients together. However, nothing bad happened, as I realized it quickly, gave a call to both of them and apologized for my mistake. Now I always double-check the letterheads to avoid making the same mistake again.
This is my first job application, so I have not made any mistakes in work yet. But I understand it will happen, because everyone makes mistakes. I will try my best to avoid them though, and I will take each mistake as a chance to learn something and to improve in work.