AP Biology
Macromolecules, cells, metabolism, genetics, evolution β everything you need to score a 5, organized by unit.
8
AP Bio Units
100+
Flashcards
6
Quiz Sets
AI
Graded FRQs
AP Bio Exam Structure
Section I β 90 min
60 MC questions β 50%
6 Grid-in questions included
60 MC questions β 50%
6 Grid-in questions included
Section II β 90 min
6 FRQ questions β 50%
2 long + 4 short answer
6 FRQ questions β 50%
2 long + 4 short answer
Score Scale
5 β Extremely well qualified
4 β Well qualified
3 β Qualified
5 β Extremely well qualified
4 β Well qualified
3 β Qualified
Flashcards
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Unit Study Guides
Key concepts, must-knows, and exam tips for every unit.
Comparison Tables
Side-by-side comparisons β high-yield for MC and FRQs.
Macromolecules
| Macromolecule | Monomer | Bond | Elements | Function |
|---|---|---|---|---|
| Carbohydrates | Monosaccharides (glucose, fructose) | Glycosidic | CHO | Quick energy, structural support (cellulose, chitin) |
| Lipids | Glycerol + fatty acids | Ester | CHO (sometimes S) | Long-term energy storage, cell membrane structure |
| Proteins | Amino acids (20 types) | Peptide | CHONS | Enzymes, structure, transport, defense, signaling |
| Nucleic Acids | Nucleotides (phosphate + sugar + base) | Phosphodiester | CHONP | Hereditary info storage (DNA), protein synthesis (RNA) |
DNA vs. RNA
| Feature | DNA | RNA |
|---|---|---|
| Strands | Double-stranded helix | Single-stranded |
| Sugar | Deoxyribose | Ribose |
| Nitrogenous bases | A, T, G, C | A, U, G, C (Uracil replaces Thymine) |
| Function | Stores hereditary information | Carries code to ribosomes; makes protein |
| Types | One type | mRNA, tRNA, rRNA, RNAi |
| Location | Nucleus (mostly) | Nucleus and cytoplasm |
Prokaryotes vs. Eukaryotes
| Feature | Prokaryotes | Eukaryotes |
|---|---|---|
| Nucleus | No β DNA in nucleoid | Yes β DNA in nucleus |
| Membrane-bound organelles | No | Yes |
| Size | 1β10 Β΅m | 10β100 Β΅m |
| DNA shape | Circular, one chromosome | Linear, multiple chromosomes |
| Histones | No | Yes |
| Found in | Bacteria | Plants, Animals, Fungi, Protists |
| In common | Both have plasma membranes, ribosomes, and carry out life functions | |
Chloroplast vs. Mitochondria
| Feature | Chloroplast | Mitochondria |
|---|---|---|
| Function | Photosynthesis β converts light to chemical energy | Cellular respiration β produces ATP from glucose |
| Found in | Plant cells only | Both plant and animal cells |
| Membranes | Outer, inner, thylakoid | Outer, inner (cristae) |
| Key compartments | Stroma, thylakoid lumen, grana | Matrix, intermembrane space |
| Own DNA? | Yes | Yes |
| Own ribosomes? | Yes | Yes |
| Endosymbiosis evidence | Double membrane, own DNA/ribosomes, can reproduce independently β similar to prokaryotes | |
Passive vs. Active Transport
| Feature | Passive Transport | Active Transport |
|---|---|---|
| Energy required? | No β moves with concentration gradient | Yes β ATP required |
| Direction | High β Low concentration | Can move against gradient |
| Types | Simple diffusion, facilitated diffusion, osmosis | Protein pumps, endocytosis, exocytosis |
| Examples | Oβ, COβ crossing membrane; water via aquaporins | NaβΊ/KβΊ pump, phagocytosis, hormone secretion |
Mitosis vs. Meiosis
| Feature | Mitosis | Meiosis |
|---|---|---|
| Purpose | Growth, repair, asexual reproduction | Sexual reproduction β produces gametes |
| Divisions | 1 | 2 (Meiosis I and II) |
| Daughter cells | 2 diploid (2n) identical cells | 4 haploid (n) unique cells |
| Crossing over? | No | Yes β in Prophase I |
| Genetic variation? | No | Yes β crossing over, independent assortment, fertilization |
| Where? | Somatic cells throughout body | Germ cells in gonads |
Competitive vs. Non-competitive Inhibition
| Feature | Competitive | Non-competitive (Allosteric) |
|---|---|---|
| Where inhibitor binds | Active site β blocks substrate | Allosteric site β different from active site |
| Effect on Vmax | Unchanged (can overcome with more substrate) | Decreased (cannot be overcome) |
| Can substrate still bind? | No β inhibitor occupies active site | Yes β but reaction is blocked |
| Example | Drug that mimics substrate shape | Feedback inhibition at end of metabolic pathway |
Cellular Respiration β Stage Summary
| Stage | Location | Inputs | Outputs | ATP Yield |
|---|---|---|---|---|
| Glycolysis | Cytosol | Glucose + 2 ATP | 2 Pyruvate + 2 NADH | Net 2 ATP |
| Krebs Cycle | Mitochondrial matrix | 2 Pyruvate + Oβ | COβ + 6 NADH + 2 FADHβ | 2 ATP |
| ETC / Oxidative Phosphorylation | Inner mitochondrial membrane | NADH + FADHβ + Oβ | HβO + NADβΊ + FADβΊ | ~34 ATP |
| Total | β | CβHββOβ + 6Oβ | 6COβ + 6HβO | ~38 ATP |
Cell Organelles β Plant vs. Animal
| Organelle | Function | Plant | Animal |
|---|---|---|---|
| Nucleus | Contains DNA; controls cell activity | β | β |
| Mitochondria | ATP production (cellular respiration) | β | β |
| Ribosome | Protein synthesis | β | β |
| Rough ER | Protein folding and sorting | β | β |
| Smooth ER | Lipid synthesis, carb metabolism, calcium storage | β | β |
| Golgi Apparatus | Processes and packages proteins/lipids | β | β |
| Chloroplast | Photosynthesis | β | β |
| Central Vacuole | Water/molecule storage, maintains turgor | β (large) | β |
| Cell Wall | Structure, support, protection | β | β |
| Lysosomes | Digest macromolecules, repair membranes | β | β |
| Centrioles | Cell division β organize microtubules | β | β |
Practice Quiz
Multiple choice questions organized by unit. Select a set to begin.
Full AP Biology Practice Test
20 MC questions covering all units, plus 2 long FRQs and 4 short FRQs β graded and analyzed by Gemini AI.
Section I β Multiple Choice (20 Questions)
Section II β Free Response
Long FRQ 1 β Cellular Respiration & Photosynthesis
A student measures the rate of oxygen production in Elodea plants under
different light intensities. At low light, Oβ production is low. As light intensity increases,
Oβ production rises until it plateaus. The student also measures COβ consumption and finds it
mirrors Oβ production.
Explain why oxygen production increases with light intensity and then
plateaus. Reference specific reactions in photosynthesis.
Explain the role of ATP and NADPH produced in the light-dependent reactions
in the Calvin Cycle. Why must COβ levels remain low for efficient photosynthesis?
Compare the location and products of photosynthesis and cellular
respiration. Explain how the products of one process serve as inputs for the other.
Long FRQ 2 β Genetics, Meiosis & Gene Expression
A plant has a genotype of AaBb, where A (tall) is dominant over a (short)
and B (purple flower) is dominant over b (white flower). The two genes are on different
chromosomes.
Predict the phenotypic ratio of offspring produced by crossing AaBb Γ AaBb.
Explain your reasoning using Mendel's laws.
Explain how crossing over during meiosis contributes to genetic variation.
At what stage does it occur and why is it more frequent toward the ends of chromosomes?
Describe how a mutation in a tumor suppressor gene (such as p53) could lead
to cancer. Include at least two other cellular changes required for full malignancy.
Short FRQ 1 β Cell Membranes & Transport
A red blood cell is placed in a solution with a solute concentration of 2%
(the cell's internal solute concentration is 0.9%).
Is this solution hypertonic, hypotonic, or isotonic relative to the cell?
What will happen to the cell?
Explain the role of aquaporins in this process. Are they an example of
passive or active transport?
Short FRQ 2 β Enzymes
An enzyme has an optimal pH of 7.4 and optimal temperature of 37Β°C.
Predict and explain what would happen to enzyme activity if the pH dropped
to 2.
Distinguish between competitive and allosteric (non-competitive) inhibition.
Give one example of where allosteric inhibition is useful in a cell.
Short FRQ 3 β Cell Signaling
A cell receives a signal from a water-soluble hormone that cannot cross the
plasma membrane.
Describe the three stages of cell signaling (reception, transduction,
response) using this scenario.
Short FRQ 4 β Evolution & Natural Selection
A population of beetles has brown and green variants. In a forest with green
foliage, predators eat more brown beetles.
Explain how natural selection will act on this population over many
generations. Reference variation, selection pressure, and heritability.
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