Here's a great AP Biology resource if you plan to give timed essays in the cell or energy unit. This essay asks students to compare and contrast the energy transforming organelles, mitochondria and chloroplasts in terms of evolutionary origin, and structure and function. The essay is provided as a word document or a PDF and includes lined paper. The rubric includes numerous statements that contribute to points (similar to the AP exam essay scoring procedure). The rubric is also provided as a word document that can be edited if with points you may want included. There are two rubrics printed on the same page as a means of paper saving.