Part of a prospectus is convincing the publisher that you are the right person to write the proposed textbook. Teaching experience is a plus; prestigious publications do not show that you can explain mitosis to a freshman. In your sample chapter, show concise writing that is inclusive, yet innovative.
WRITING AND REWRITING CYCLE
The goal is to satisfy reviewers (course instructors) while retaining the flavor and rationale of your book. Reviewers can be wrong. When in doubt, check it out.
You will check and recheck art.
Are the mitochondria the same color in each chapter?
Do the nucleotides have the right bonds?
Are colors too garish, or too pale?
Did an artist take liberties with style and ruin the meaning or accuracy?
Do the DNA sequences obey the base pair rules?
Do all the ATPs add up?