What are the most important concepts/objectives to focus on in Freshman high school life science?

I am tutoring a homeschool high school freshman in life science.  He has no curriculum or books so I have been using our state standards and basically winging it with supplemental materials.  I have covered animal and plant cell structure, mitosis and photosynthesis.  We also have discussed Darwin's theory of evolution and the evolutionary process in mainly primates- apes/humans and wolves/dogs.  We recently have covered habitats and ecosystems in a general sense.  What else should I include over the next three weeks?  He has major test anxiety so I stay away from big exams and give him short quizzes every week.  All help is appreciated!