One form of external knowledge assesment is the national assessment of knowledge at the end of the ninth grade in elementary schools. External testing tries to acquire the most objective and accurate insight into students knowledge. With national assessment of knowledge we enable students, their parents, teachers, schools and instituitions dealing with education to excess information about success in achieving objectives and standards, provided in national curriculum and allow them to check quality of teaching and learning. With this kind of assessment we can determine deficiencies and with their help we can improve how we teach and learn in the future. In the school year 2011/2012, one of the four subjects being assessed in the national assessment of knowledge was biology. There where 5683 participants in the national assessment of knowledge in biology. There average score was 48,02%. Results are also available on the website of the National Examination Centre, which conducted the national assessment of knowledge. The disadvantage of the results is that they are based only on the difference betwen the correct answers and all other replies. Due to the fact that even not fully correct answers contain vital information about students knowledge, it is sensible to conduct an the even more thorough analysis of national assessment of knowledge. That is why in our analysis we will focus on the partially correct, partially incorrect and incorrect answers. By analysing randomly selected examinations from national assessment of knowlegde 2011 (184 examinations), we will acquire more detailed information about knowledge in biology at the end of the ninth grade.