Assessment is an integral and vital part of teaching and learning, providing feedback on progress through the assessment period to both learners and teachers. However, if test items are flawed because of misconceptions held by the question setter, then such test items are invalid as assessment tools. Moreover, such flawed items are also likely to generate or perpetuate misconceptions among pupils. Research has shown that misconceptions among pupils are resistant to change, and that they persist even with formal science instruction. This paper highlights question setters' (or teachers') misconceptions concerning some key primary school level biological science concepts in the areas of cells, plant and animal systems and functions. It is based on a scrutiny of more than 200 sets of primary science examination papers in schools (first and second semestral assessment science papers, i.e. SA1 and SA2) in three different contexts: 1) vetting school examination papers with a view to helping schools improve the quality of their examination questions; 2) conducting school-based workshops on how to craft better examination questions; 3) conducting in-service courses for primary school teachers. Suggestions for addressing the problems highlighted are also discussed. (Contains 1 figure and 9 example questions.)