A differentiated open assessment task. This should be set at the end of the teaching the circulatory system and diffusion/osmosis units to check understanding. A rubric is included so students are aware of what the teacher is looking for. I teach in the British System but you can adapt the grade boundaries to fit in with your own system.
The assessment is formative which means teachers can guide students, enabling them to modify their assessments, increasing their knowledge and self confidence.