AP Biology · Key concepts
The AP Bio cheat sheet: every concept the exam keeps coming back to.
Cell processes · Genetics & evolution · Ecology — plus the FRQ moves that turn knowledge into points.
days until your AP Bio exam
Mon, May 4 · Morning session
Concepts
What the MCQ keeps testing
Membrane transport & cell signaling
Active vs. passive, signal cascades — show up in every concept-application set.
Photosynthesis & cellular respiration
Inputs, outputs, and where ATP/NADPH actually come from.
Genetics flow: DNA → RNA → protein
Mutations, transcription, translation, and the consequence at each step.
Natural selection & Hardy-Weinberg
Allele frequency math + the conditions that have to hold for it to apply.
Lab + Data
Reading graphs and experiments
Independent vs. dependent variable
Name them in the study's own terms — generic 'time' or 'amount' loses points.
Controls & confounds
What's held constant and why. Missing this caps experimental design FRQs.
Graph trend → biology claim
Cite the pattern in the data first, then explain the mechanism.
Predicting from a mutation
Trace molecular change → process change → organism-level effect in three links.
FRQ moves
How to actually score
Justify with mechanism, not vocab
'Because diffusion happens' isn't justification. Name the driver.
Answer every task verb
Identify, predict, justify, describe — each verb is a separate scoring point.
Claim · evidence · reasoning blocks
Short FRQs reward this 3-line structure over miniature essays.
Quantitative comparisons
When asked to compare, do the math or estimate — don't hedge.
Exam at a glance · 3 hours total
60 MCQs · 90 min
About 1.5 min per question.
2 Long FRQs · 45 min
~22 min each, full task list.
4 Short FRQs · 45 min
Tight claim-evidence-reasoning.
FRQs = 50% · of score
Section weights are even.
What AP Bio readers actually reward
Three FRQ habits that separate students who 'know the bio' from students who score it.
Rubric move
Mechanism > vocabulary
Naming the term doesn't earn the point. Explaining why the molecule, cell, or system behaves that way does.
Weak
The enzyme works through enzyme-substrate specificity.
Scoring-ready
The substrate fits the enzyme's active site, allowing the enzyme to lower activation energy and catalyze the reaction.
Rubric move
Cite data before claiming
Graph FRQs reward the order: name the trend in the data, THEN explain the biology behind it.
Weak
Higher temperature denatures the enzyme.
Scoring-ready
Activity rises until 40°C, then drops sharply — consistent with denaturation as hydrogen bonds in the active site break.
Rubric move
Three-link causal chains
Predict-the-effect prompts want molecular → cellular → organism. Skipping a link costs the reasoning point.
Weak
A mutation in the transport protein would harm the cell.
Scoring-ready
The mutation prevents Na⁺ transport → ion gradient collapses → water cannot follow → cell dehydrates.
Want to see exactly which FRQ row you're losing points on?
Spot the concept
These are the concepts behind a real AP Bio stem.
Three mini MCQs from the exam's most common skill areas. Tap to reveal the answer.
Which factor most likely limits the rate of photosynthesis at the plateau?
- AAvailability of light-independent-reaction substrates such as CO₂.
- BThe number of photons striking the leaves.
- CWater availability inside the plant.
- DThe amount of chlorophyll in the stroma.
In a large, randomly mating population at Hardy-Weinberg equilibrium, 16% of individuals express a recessive phenotype. What fraction of the population is heterozygous?
- A0.16
- B0.24
- C0.36
- D0.48
Which single change would most improve the validity of her experiment?
- AUsing a larger, standardized sample size and repeating measurements at multiple caffeine concentrations.
- BIncreasing the caffeine concentration tenfold to make the effect larger.
- CUsing only Daphnia that happened to have visible heartbeats in the first trial.
- DCombining all the Daphnia into one beaker so conditions are identical.
Will you score the 5?
Write one timed FRQ. See exactly where rubric points would slip — while there's still time to fix it.
Quick questions
Cellular energetics, heredity, gene expression, and natural selection consistently dominate the MCQ section and feed most long FRQs. If your time is tight, those four are the highest-leverage units to drill.
Use a fixed template every time: independent variable, dependent variable, control, what data you collect, and what result would support the hypothesis. Skipping any one of these is the most common cap on the score.
No. The exam rewards explaining mechanism and predicting consequences from data. Vocabulary without a 'because' sentence almost never earns the FRQ point.
60 MCQs. 6 FRQs. The 5 lives in the FRQ section.
Or if you want a schedule.