HESI A2 Biology Study Guide
The cell and everything it does: its chemistry, its division, its genetics, and the microbes and immunity around it.
30 questions · 25minutes on the real exam · 5 units · 13 lessons · updated July 2026
Foundations of Biology
~24% of the sectionStart with the scientific method, the chemistry of water, and homeostasis.
- 01Scientific method and taxonomyFree lesson
- 02The chemistry of water
- 03Homeostasis
Cell Biology
~24% of the sectionLockedLearn the organelles, how the membrane moves things, and how cells make energy.
Cell Division and Genetics
~20% of the sectionLockedFollow mitosis and meiosis, then predict inheritance with Punnett squares.
Molecular Biology
~16% of the sectionLockedSee how DNA copies itself and how a gene becomes a protein.
Microbiology and Immunity
~16% of the sectionLockedMeet the pathogens that cause disease and the immune system that answers them.
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