Keep the big ideas close.
Sixteen connected biology concepts, from cell theory to energy pyramids. Each note states the key idea in one line, works a real example with numbers, and names the mistake most people make — then hands you a tool where you can see the idea move.
Start with the cell
Build from the smallest unit of life outward.
Make sense of genetics
Follow information from a double helix to a cross.
Explore the living world
From one population to a whole ecosystem.
Every concept, in one place
Read them in order for a quick course, or jump straight to the idea you are revising.
Cell theory
Three statements that every living thing obeys.
Prokaryotes vs. eukaryotes
Two cell plans: one with a nucleus, one without.
Cell transport & osmosis
How water, ions, and molecules cross a membrane.
DNA structure
A twisted ladder built from four bases.
Transcription & translation
From a gene to a working protein, in two steps.
Mitosis & meiosis
Copy a cell, or halve its chromosome set.
Mendelian inheritance
Alleles, dominance, and predictable ratios.
The Hardy-Weinberg principle
The baseline of a population that isn’t evolving.
Natural selection
Variation, heredity, and who leaves more offspring.
Enzymes & activation energy
Biological catalysts that lower the energy hill.
Photosynthesis
Light, water, and CO₂ become sugar and oxygen.
Cellular respiration
Glucose comes apart, and ATP captures the energy.
Population growth models
Exponential with no limits, logistic with them.
Energy flow in ecosystems
Why so little sunlight reaches the top predator.
Surface area to volume ratio
The geometry that keeps cells small.
Lab measurements & scale
Turn what you see in a microscope into numbers.
Read a note, then test it.
Eight quick questions on cells, genetics, molecules, ecology, or physiology, each with an explanation.