Master Biology from first principles
Texas CBE prep · TEKS §112.42 (NOT AP® Biology). Cells, genetics, ecology, evolution, and body systems. This service prepares Texas HS-level Biology for CBE credit through UT High School / Texas Tech K-12; it is not designed for the College Board AP® Biology exam. AP® is a registered trademark of the College Board, which was not involved with this product.
Biology — Essential Concepts (Quick Reference)
Cell biology, genetics, evolution, ecosystems — every Biology CBE essential summarized on one page for last-minute review.
Cell Structure & Organelles: A Tour Inside the Cell
Every Texas Biology CBE has at least one organelle-identification question. Master the eight structures every cell biology question is built around — what each one looks like, what it does, and how plant cells differ from animal cells.
Cell Membrane & Transport: How Things Get In and Out
The cell membrane is the boundary that decides what enters and leaves. Master the phospholipid bilayer, transport proteins, osmosis, diffusion, and active transport in one focused lesson.
Cell Cycle & Mitosis: How One Cell Becomes Two
The CBE tests both the cell cycle macro-phases (G1/S/G2/M) and the mitosis substages (Prophase, Metaphase, Anaphase, Telophase). Master both levels and how they connect.
Mitosis vs Meiosis: Two Divisions, Two Outcomes
Mitosis and meiosis sound similar but serve completely different purposes. Master the four key differences (cell count, ploidy, purpose, genetic identity) and you'll never miss a comparison question.
DNA Structure & Replication: The Code of Life and How It Copies Itself
Three things every CBE asks: the four bases (A, T, G, C) and how they pair, the double helix structure, and semi-conservative replication. Plus the four enzymes that make replication work.
Genetics & Punnett Squares: Predicting Inheritance with a 2×2 Grid
The Punnett square is the single most-tested tool on the Biology CBE. Master monohybrid crosses, dihybrid crosses, and the four key terms — homozygous, heterozygous, dominant, recessive.
Evolution & Natural Selection: How Populations Change Over Time
Natural selection isn't 'survival of the strongest' — it's differential reproduction based on heritable variation. Master Darwin's mechanism, the evidence for evolution, and the famous Galápagos finches.
Ecology: Food Webs, Trophic Levels & Energy Flow
Producers, primary consumers, secondary consumers, tertiary consumers, decomposers — and the 10% rule that connects them. Master food chains, food webs, and energy pyramids in one focused lesson.
Biogeochemical Cycles: Carbon, Water & Nitrogen
Atoms cycle through ecosystems endlessly. Master the carbon cycle (photosynthesis ↔ respiration), the water cycle (evaporation/precipitation), and the nitrogen cycle (fixation + denitrification).
Human Body Systems & Classification
Two topics in one lesson. Human body systems — respiratory and circulatory — are assessed on the current Biology CBE (TEKS 12A, 12B). Classification (the taxonomic hierarchy, the three domains of life) is no longer on the exam, since the 2020 Biology TEKS removed taxonomy, but the biology is real and worth knowing.