MCAT preparation · section study Online Center
MCAT Biological and Biochemical Foundations Online Center
This MCAT Biological and Biochemical Foundations Online Center brings together practice, lessons, worksheets, flashcards and review tools. Choose the resource that matches the skill you want to work on next.
Section at a glance
59 questions10 passage sets plus 15 discrete questions
95 minutesPeriodic table available
4guided lessons
145review cards
Use the mini-test to practice timing, not to predict an official scaled score.
Start here: four study tools
Learn the concept, check the skill, review the miss, and then return to timed practice.
Timed practice
Mini Tests
Complete an original section-focused set and read every explanation.
Untimed check
Skill Quizzes
Isolate one skill before you return to mixed timed work.
Learn and repair
Topic Lessons
Open a focused lesson, apply the move, and connect it to a passage or data display.
Recall and review
Review Decks
Use Quick Review after a miss, then use active recall with Flashcards.
The Exam at a Glance
This Online Center follows the current AAMC section structure. The practice materials below are original independent study content, not official AAMC questions.
59 questionsLink molecules, cells, genetics, and organ systems to experimental passages, homeostasis, and biological cause-and-effect.
10 passage sets plus 15 discrete questionsLink molecules, cells, genetics, and organ systems to experimental passages, homeostasis, and biological cause-and-effect.
95 minutesLink molecules, cells, genetics, and organ systems to experimental passages, homeostasis, and biological cause-and-effect.
Periodic table availableLink molecules, cells, genetics, and organ systems to experimental passages, homeostasis, and biological cause-and-effect.
MCAT Biological and Biochemical Foundations Study Online Center Lessons
Learn one concept, connect it to a passage or data display, then check it with a short quiz.
1. Follow the molecule
Core idea: Biochemistry questions become easier when you track where a molecule starts, what changes it, and where it ends.
Practice move: Draw a short pathway and label the compartment, enzyme, or transporter involved.
Example: If a mutation reduces an enzyme’s activity, predict the substrate and product changes before evaluating the answer choices.
2. Use the control group
Core idea: A treatment effect requires a meaningful comparison, not simply a change over time.
Practice move: Identify the manipulated variable, measured outcome, control condition, and possible confounder.
Example: If treated cells grow faster than before, compare them with untreated cells grown under the same conditions.
3. Keep homeostasis directional
Core idea: A regulated variable can move away from its set point and trigger a response that reduces the disturbance.
Practice move: State the initial change, sensor, signal, target, and resulting correction.
Example: When blood glucose rises, insulin promotes uptake and storage, helping bring glucose toward its usual range.
4. Connect structure to function
Core idea: The MCAT often asks why a structure is suited to its job.
Practice move: Name the physical or chemical property that makes the structure effective.
Example: A folded protein can create a specific active site because three-dimensional shape positions side chains precisely.
MCAT Biological and Biochemical Foundations Study Online Center Blueprint
Use the blueprint to choose the next lesson or quiz. It is a study map, not an official question distribution.
Molecules and cells
- Amino acids and proteins
- Enzymes
- Membranes and organelles
Genetics and information
- DNA and RNA
- Replication and expression
- Inheritance and biotechnology
Systems physiology
- Homeostasis
- Cardiovascular and respiratory
- Renal and endocrine
Experimental biology
- Controls and variables
- Data interpretation
- Evolution and adaptation
MCAT Biological and Biochemical Foundations Study Online Center Topics: Learn and Review
Use one topic at a time. After a miss, name the skill, review the lesson, and retest.
- Amino acids and proteins
- Enzyme kinetics
- Membranes and transport
- Cell cycle
- DNA replication
- Transcription and translation
- Genetics
- Metabolism
- Immune system
- Cardiovascular system
- Respiratory system
- Renal and endocrine systems
- Homeostasis
- Experimental design
A simple study path
1
Diagnose
Take a mini-test and mark uncertain answers as well as incorrect ones.
2
Learn
Open the lesson for the concept or reasoning skill behind the miss.
3
Check
Use a no-timer quiz and read every explanation.
4
Retest
Return to the second timed mini-test once the method is repeatable.
MCAT Biological and Biochemical Foundations Study Online Center FAQ
Are these official AAMC questions?
No. These are original independent practice materials informed by the public AAMC content outline. They are not copied from secure AAMC content.
How long is the real section?
95 minutes for this section. The mini-tests here use a shorter study timer so you can practice a focused set in one sitting.
What should I do after a missed question?
Read the explanation, name the concept or reasoning move, open the matching lesson or Quick Review card, and try a nearby question before retesting.
This is an independent MCAT preparation resource. MCAT and AAMC are trademarks of the Association of American Medical Colleges, which does not endorse this page.
Biological and Biochemical Foundations Study Online Center · Mini Test 1
Before you begin
Format6 original questions · 20 minutes
FocusLink molecules, cells, genetics, and organ systems to experimental passages, homeostasis, and biological cause-and-effect.
ReviewSubmit to see the score and every explanation.
This is an independent timed mini-set, not an official AAMC form or score conversion. The timer starts after you select Begin Test.
Time remaining: 20:00
1. An enzyme’s activity decreases when a molecule binds at a site away from the active site. This molecule most likely acts as:
Explanation: Binding away from the active site and reducing activity describes allosteric inhibition.
2. A cell is placed in a solution with a higher effective solute concentration than its cytoplasm. Water will tend to:
Explanation: Water moves toward the side with higher effective solute concentration.
3. A mutation changes one codon but does not change the amino acid sequence. This is a:
Explanation: A codon change with no amino acid change is silent because of the redundancy of the genetic code.
4. After a meal, insulin increases glucose uptake in target cells. This response helps maintain:
Explanation: Insulin helps return blood glucose toward a regulated range.
5. In an experiment, only the treated group receives a drug while both groups are measured at the same time. The untreated group is the:
Explanation: The untreated group supplies the comparison condition for the drug treatment.
6. If oxygen is unavailable to a cell, oxidative phosphorylation is most directly limited because:
Explanation: Oxygen accepts electrons at the end of the respiratory chain; without it, electron flow and proton-gradient production are disrupted.
Biological and Biochemical Foundations Study Online Center · Mini Test 2
Before you begin
Format6 original questions · 20 minutes
FocusLink molecules, cells, genetics, and organ systems to experimental passages, homeostasis, and biological cause-and-effect.
ReviewSubmit to see the score and every explanation.
This is an independent timed mini-set, not an official AAMC form or score conversion. The timer starts after you select Begin Test.
Time remaining: 20:00
1. A competitive inhibitor is added to an enzyme reaction. Which change is expected in a basic Michaelis-Menten model?
Explanation: A competitive inhibitor competes at the active site; more substrate is needed to reach half-maximal velocity, while Vmax can be reached at high substrate.
2. A diploid cell completes meiosis. The resulting cells are generally:
Explanation: Meiosis reduces chromosome number and creates variation through recombination and independent assortment.
3. A hormone binds an intracellular receptor. The hormone is most likely:
Explanation: Lipid-soluble hormones can cross the membrane and bind receptors inside the cell.
4. A patient’s ventilation decreases while carbon dioxide production stays constant. Blood carbon dioxide will tend to:
Explanation: Lower ventilation removes less carbon dioxide, so carbon dioxide rises and can lower blood pH.
5. A population becomes separated by a geographic barrier and diverges over many generations. This can contribute to:
Explanation: Geographic isolation can reduce gene flow and allow divergence, producing allopatric speciation.
6. A protein loses its function after a change in pH alters its three-dimensional shape. The change most directly affects the protein’s:
Explanation: pH can disrupt interactions that maintain secondary, tertiary, or quaternary structure.
Biological and Biochemical Foundations Study Online Center · Skill Quiz A
Short skill check
Format4 original questions · no timer
FocusMolecules and cells
ReviewUse the explanation to choose your next lesson.
This is independent study practice, not an official AAMC score.
1. An enzyme’s activity decreases when a molecule binds at a site away from the active site. This molecule most likely acts as:
Explanation: Binding away from the active site and reducing activity describes allosteric inhibition.
2. A cell is placed in a solution with a higher effective solute concentration than its cytoplasm. Water will tend to:
Explanation: Water moves toward the side with higher effective solute concentration.
3. A mutation changes one codon but does not change the amino acid sequence. This is a:
Explanation: A codon change with no amino acid change is silent because of the redundancy of the genetic code.
4. After a meal, insulin increases glucose uptake in target cells. This response helps maintain:
Explanation: Insulin helps return blood glucose toward a regulated range.
Biological and Biochemical Foundations Study Online Center · Skill Quiz B
Short skill check
Format4 original questions · no timer
FocusExperimental biology
ReviewUse the explanation to choose your next lesson.
This is independent study practice, not an official AAMC score.
1. A competitive inhibitor is added to an enzyme reaction. Which change is expected in a basic Michaelis-Menten model?
Explanation: A competitive inhibitor competes at the active site; more substrate is needed to reach half-maximal velocity, while Vmax can be reached at high substrate.
2. A diploid cell completes meiosis. The resulting cells are generally:
Explanation: Meiosis reduces chromosome number and creates variation through recombination and independent assortment.
3. A hormone binds an intracellular receptor. The hormone is most likely:
Explanation: Lipid-soluble hormones can cross the membrane and bind receptors inside the cell.
4. A patient’s ventilation decreases while carbon dioxide production stays constant. Blood carbon dioxide will tend to:
Explanation: Lower ventilation removes less carbon dioxide, so carbon dioxide rises and can lower blood pH.
Biological and Biochemical Foundations Study Online Center · Quick Review
Use this quick review after a missed question. Say the idea aloud, then return to the matching lesson.
Amino-acid structureAmino acids share a backbone but differ in side-chain chemistry.
Case: A controlled study compares 24 participants or samples in Group A with 24 in Group B. The groups differ only in the condition represented by “Amino-acid structure”; the measured outcome is 15 units in Group A and 18 units in Group B. What comparison, mechanism, or limitation should you use before interpreting that difference?Answer: The observed difference is 3 units, but interpret it only after checking that the groups were comparable, the outcome was measured reliably, and the condition represented by “Amino-acid structure” is a defensible explanation. Core concept: Amino acids share a backbone but differ in side-chain chemistry. Concept: Amino acids share a backbone but differ in side-chain chemistry.
Amino-acid structure — common trapThe peptide bond does not erase side-chain properties.
Amino-acid structure — recognize itRecognition cue: Classify the side chain before predicting location or interaction. Then state the predicted consequence in your own words before looking at the answer choices.
Amino-acid structure — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? Use side-chain charge, polarity, and hydrophobicity to predict protein interactions. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
Protein structurePrimary through quaternary structure describe increasingly complex levels of organization.
Case: A controlled study compares 27 participants or samples in Group A with 27 in Group B. The groups differ only in the condition represented by “Protein structure”; the measured outcome is 15 units in Group A and 21 units in Group B. What comparison, mechanism, or limitation should you use before interpreting that difference?Answer: The observed difference is 6 units, but interpret it only after checking that the groups were comparable, the outcome was measured reliably, and the condition represented by “Protein structure” is a defensible explanation. Core concept: Primary through quaternary structure describe increasingly complex levels of organization. Concept: Primary through quaternary structure describe increasingly complex levels of organization.
Protein structure — common trapDenaturation often disrupts higher-order structure without breaking every peptide bond.
Protein structure — recognize itRecognition cue: Ask which interactions stabilize the level in question. Then state the predicted consequence in your own words before looking at the answer choices.
Protein structure — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? Predict how a mutation or environment change could disrupt folding or function. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
Peptide bondA covalent amide linkage joins the carboxyl group of one amino acid to the amino group of another.
Case: A controlled study compares 34 participants or samples in Group A with 34 in Group B. The groups differ only in the condition represented by “Peptide bond”; the measured outcome is 14 units in Group A and 17 units in Group B. What comparison, mechanism, or limitation should you use before interpreting that difference?Answer: The observed difference is 3 units, but interpret it only after checking that the groups were comparable, the outcome was measured reliably, and the condition represented by “Peptide bond” is a defensible explanation. Core concept: A covalent amide linkage joins the carboxyl group of one amino acid to the amino group of another. Concept: A covalent amide linkage joins the carboxyl group of one amino acid to the amino group of another.
Peptide bond — common trapPeptide bonds are not hydrogen bonds.
Peptide bond — recognize itRecognition cue: Locate the backbone linkage between residues. Then state the predicted consequence in your own words before looking at the answer choices.
Peptide bond — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? Track water loss during condensation and hydrolysis during digestion. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
Enzyme active siteThe active site positions substrate and stabilizes the transition state.
Case: A mutation changes one amino acid lining an enzyme pocket while substrate concentration stays fixed. Which feature of the reaction could change first: binding, catalytic rate, or neither?Answer: A pocket mutation can change substrate binding and catalytic rate because active-site shape and interactions have changed. Concept: The active site positions substrate and stabilizes the transition state.
Enzyme active site — common trapBinding and catalysis are related but not identical measurements.
Enzyme active site — recognize itRecognition cue: Look for substrate complementarity and transition-state stabilization. Then state the predicted consequence in your own words before looking at the answer choices.
Enzyme active site — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? A mutation near the active site can change specificity, affinity, or catalytic rate. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
Allosteric regulationBinding at a site separate from the active site changes protein conformation or activity.
Case: A controlled study compares 32 participants or samples in Group A with 32 in Group B. The groups differ only in the condition represented by “Allosteric regulation”; the measured outcome is 16 units in Group A and 19 units in Group B. What comparison, mechanism, or limitation should you use before interpreting that difference?Answer: The observed difference is 3 units, but interpret it only after checking that the groups were comparable, the outcome was measured reliably, and the condition represented by “Allosteric regulation” is a defensible explanation. Core concept: Binding at a site separate from the active site changes protein conformation or activity. Concept: Binding at a site separate from the active site changes protein conformation or activity.
Allosteric regulation — common trapAllosteric binding is not automatically competitive inhibition.
Allosteric regulation — recognize itRecognition cue: The regulator binds away from the catalytic site. Then state the predicted consequence in your own words before looking at the answer choices.
Allosteric regulation — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? An allosteric activator or inhibitor can alter Vmax or apparent affinity. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
Michaelis-Menten kineticsReaction velocity rises with substrate concentration and approaches Vmax as enzyme sites saturate.
Case: A velocity-versus-substrate plot rises rapidly and then plateaus. What does the plateau imply about active-site occupancy?Answer: The plateau indicates that the finite enzyme population is approaching saturation; adding substrate no longer raises velocity proportionally. Concept: Reaction velocity rises with substrate concentration and approaches Vmax as enzyme sites saturate.
Michaelis-Menten kinetics — common trapKm is not always a direct binding constant.
Michaelis-Menten kinetics — recognize itRecognition cue: Look for a hyperbolic curve and a plateau. Then state the predicted consequence in your own words before looking at the answer choices.
Michaelis-Menten kinetics — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? Use Km as the substrate concentration at half Vmax under the model. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
Competitive inhibitionA competitor occupies the active site and can often be overcome by increasing substrate.
Case: An inhibitor occupies the same active site as substrate. What change in apparent Km and Vmax should the simple model predict when substrate is increased?Answer: The simple model predicts increased apparent Km with unchanged Vmax when enough substrate can outcompete the inhibitor. Concept: A competitor occupies the active site and can often be overcome by increasing substrate.
Competitive inhibition — common trapA competitive inhibitor does not necessarily destroy the enzyme.
Competitive inhibition — recognize itRecognition cue: The inhibitor and substrate compete for the same site. Then state the predicted consequence in your own words before looking at the answer choices.
Competitive inhibition — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? Expect apparent Km to rise while Vmax remains unchanged in the simple model. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
CarbohydratesMonosaccharides, disaccharides, and polysaccharides provide energy or structural material.
Case: A controlled study compares 34 participants or samples in Group A with 34 in Group B. The groups differ only in the condition represented by “Carbohydrates”; the measured outcome is 12 units in Group A and 15 units in Group B. What comparison, mechanism, or limitation should you use before interpreting that difference?Answer: The observed difference is 3 units, but interpret it only after checking that the groups were comparable, the outcome was measured reliably, and the condition represented by “Carbohydrates” is a defensible explanation. Core concept: Monosaccharides, disaccharides, and polysaccharides provide energy or structural material. Concept: Monosaccharides, disaccharides, and polysaccharides provide energy or structural material.
Carbohydrates — common trapNot all carbohydrates are rapidly absorbed as glucose.
Carbohydrates — recognize itRecognition cue: Identify sugar units and linkage type. Then state the predicted consequence in your own words before looking at the answer choices.
Carbohydrates — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? Relate glycosidic linkage and branching to digestion and storage. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
LipidsHydrophobic molecules function in energy storage, membranes, and signaling.
Case: A controlled study compares 35 participants or samples in Group A with 35 in Group B. The groups differ only in the condition represented by “Lipids”; the measured outcome is 16 units in Group A and 24 units in Group B. What comparison, mechanism, or limitation should you use before interpreting that difference?Answer: The observed difference is 8 units, but interpret it only after checking that the groups were comparable, the outcome was measured reliably, and the condition represented by “Lipids” is a defensible explanation. Core concept: Hydrophobic molecules function in energy storage, membranes, and signaling. Concept: Hydrophobic molecules function in energy storage, membranes, and signaling.
Lipids — common trapLipids are not all chemically identical or insoluble in every context.
Lipids — recognize itRecognition cue: Look for long hydrocarbon regions and ester bonds. Then state the predicted consequence in your own words before looking at the answer choices.
Lipids — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? Use saturation and chain structure to predict membrane fluidity. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
Membrane structureA phospholipid bilayer creates a selectively permeable, dynamic boundary.
Case: A controlled study compares 32 participants or samples in Group A with 32 in Group B. The groups differ only in the condition represented by “Membrane structure”; the measured outcome is 15 units in Group A and 22 units in Group B. What comparison, mechanism, or limitation should you use before interpreting that difference?Answer: The observed difference is 7 units, but interpret it only after checking that the groups were comparable, the outcome was measured reliably, and the condition represented by “Membrane structure” is a defensible explanation. Core concept: A phospholipid bilayer creates a selectively permeable, dynamic boundary. Concept: A phospholipid bilayer creates a selectively permeable, dynamic boundary.
Membrane structure — common trapSmall and nonpolar does not mean every molecule crosses equally fast.
Membrane structure — recognize itRecognition cue: Compare size, charge, polarity, and lipid solubility. Then state the predicted consequence in your own words before looking at the answer choices.
Membrane structure — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? Predict which molecules cross directly and which require proteins. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
Passive transportDiffusion moves substances down a concentration or electrochemical gradient without direct ATP use.
Case: A controlled study compares 31 participants or samples in Group A with 31 in Group B. The groups differ only in the condition represented by “Passive transport”; the measured outcome is 14 units in Group A and 20 units in Group B. What comparison, mechanism, or limitation should you use before interpreting that difference?Answer: The observed difference is 6 units, but interpret it only after checking that the groups were comparable, the outcome was measured reliably, and the condition represented by “Passive transport” is a defensible explanation. Core concept: Diffusion moves substances down a concentration or electrochemical gradient without direct ATP use. Concept: Diffusion moves substances down a concentration or electrochemical gradient without direct ATP use.
Passive transport — common trapFacilitated diffusion uses a protein but is still passive.
Passive transport — recognize itRecognition cue: Ask whether movement is down-gradient and whether ATP is used. Then state the predicted consequence in your own words before looking at the answer choices.
Passive transport — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? Distinguish simple diffusion, facilitated diffusion, and osmosis by mechanism. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
Active transportTransport against a gradient requires energy directly or through a coupled gradient.
Case: A controlled study compares 38 participants or samples in Group A with 38 in Group B. The groups differ only in the condition represented by “Active transport”; the measured outcome is 13 units in Group A and 15 units in Group B. What comparison, mechanism, or limitation should you use before interpreting that difference?Answer: The observed difference is 2 units, but interpret it only after checking that the groups were comparable, the outcome was measured reliably, and the condition represented by “Active transport” is a defensible explanation. Core concept: Transport against a gradient requires energy directly or through a coupled gradient. Concept: Transport against a gradient requires energy directly or through a coupled gradient.
Active transport — common trapA channel is not automatically an active transporter.
Active transport — recognize itRecognition cue: Find the gradient and the energy source. Then state the predicted consequence in your own words before looking at the answer choices.
Active transport — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? Use pump direction and ATP use to predict concentration changes. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
OrganellesOrganelles compartmentalize synthesis, trafficking, energy conversion, and degradation.
Case: A controlled study compares 30 participants or samples in Group A with 30 in Group B. The groups differ only in the condition represented by “Organelles”; the measured outcome is 10 units in Group A and 18 units in Group B. What comparison, mechanism, or limitation should you use before interpreting that difference?Answer: The observed difference is 8 units, but interpret it only after checking that the groups were comparable, the outcome was measured reliably, and the condition represented by “Organelles” is a defensible explanation. Core concept: Organelles compartmentalize synthesis, trafficking, energy conversion, and degradation. Concept: Organelles compartmentalize synthesis, trafficking, energy conversion, and degradation.
Organelles — common trapRibosomes make protein but do not package or secrete it.
Organelles — recognize itRecognition cue: Follow the molecule through the endomembrane system. Then state the predicted consequence in your own words before looking at the answer choices.
Organelles — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? Match a cellular task to the organelle whose structure supports it. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
Cell cycleG1, S, G2, and M phases coordinate growth, DNA replication, and division.
Case: A controlled study compares 26 participants or samples in Group A with 26 in Group B. The groups differ only in the condition represented by “Cell cycle”; the measured outcome is 10 units in Group A and 15 units in Group B. What comparison, mechanism, or limitation should you use before interpreting that difference?Answer: The observed difference is 5 units, but interpret it only after checking that the groups were comparable, the outcome was measured reliably, and the condition represented by “Cell cycle” is a defensible explanation. Core concept: G1, S, G2, and M phases coordinate growth, DNA replication, and division. Concept: G1, S, G2, and M phases coordinate growth, DNA replication, and division.
Cell cycle — common trapChromosome number and DNA amount are different measures.
Cell cycle — recognize itRecognition cue: Ask whether DNA has replicated and whether sister chromatids separated. Then state the predicted consequence in your own words before looking at the answer choices.
Cell cycle — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? Use DNA content and chromosome state to distinguish phases. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
DNA replicationSemiconservative replication uses complementary base pairing and antiparallel templates.
Case: A controlled study compares 35 participants or samples in Group A with 35 in Group B. The groups differ only in the condition represented by “DNA replication”; the measured outcome is 8 units in Group A and 14 units in Group B. What comparison, mechanism, or limitation should you use before interpreting that difference?Answer: The observed difference is 6 units, but interpret it only after checking that the groups were comparable, the outcome was measured reliably, and the condition represented by “DNA replication” is a defensible explanation. Core concept: Semiconservative replication uses complementary base pairing and antiparallel templates. Concept: Semiconservative replication uses complementary base pairing and antiparallel templates.
DNA replication — common trapDNA polymerase extends from a primer; it does not begin from nothing.
DNA replication — recognize itRecognition cue: Look for template, primer, leading, and lagging strands. Then state the predicted consequence in your own words before looking at the answer choices.
DNA replication — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? Predict the effect of a polymerase, primer, or proofreading defect. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
TranscriptionRNA polymerase makes RNA from a DNA template using complementary base pairing.
Case: A controlled study compares 25 participants or samples in Group A with 25 in Group B. The groups differ only in the condition represented by “Transcription”; the measured outcome is 14 units in Group A and 21 units in Group B. What comparison, mechanism, or limitation should you use before interpreting that difference?Answer: The observed difference is 7 units, but interpret it only after checking that the groups were comparable, the outcome was measured reliably, and the condition represented by “Transcription” is a defensible explanation. Core concept: RNA polymerase makes RNA from a DNA template using complementary base pairing. Concept: RNA polymerase makes RNA from a DNA template using complementary base pairing.
Transcription — common trapTranscription makes RNA, not protein.
Transcription — recognize itRecognition cue: Locate promoter, template strand, and RNA product. Then state the predicted consequence in your own words before looking at the answer choices.
Transcription — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? A regulatory sequence or transcription factor can change mRNA abundance. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
TranslationRibosomes read mRNA codons and assemble a polypeptide using tRNAs.
Case: A controlled study compares 25 participants or samples in Group A with 25 in Group B. The groups differ only in the condition represented by “Translation”; the measured outcome is 11 units in Group A and 19 units in Group B. What comparison, mechanism, or limitation should you use before interpreting that difference?Answer: The observed difference is 8 units, but interpret it only after checking that the groups were comparable, the outcome was measured reliably, and the condition represented by “Translation” is a defensible explanation. Core concept: Ribosomes read mRNA codons and assemble a polypeptide using tRNAs. Concept: Ribosomes read mRNA codons and assemble a polypeptide using tRNAs.
Translation — common trapThe anticodon is on tRNA; the codon is on mRNA.
Translation — recognize itRecognition cue: Track codon, anticodon, amino acid, and ribosome. Then state the predicted consequence in your own words before looking at the answer choices.
Translation — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? A frameshift changes downstream codon reading and may introduce a stop. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
Gene regulationCells control when and where genes are expressed through regulatory proteins and chromatin state.
Case: A controlled study compares 26 participants or samples in Group A with 26 in Group B. The groups differ only in the condition represented by “Gene regulation”; the measured outcome is 16 units in Group A and 20 units in Group B. What comparison, mechanism, or limitation should you use before interpreting that difference?Answer: The observed difference is 4 units, but interpret it only after checking that the groups were comparable, the outcome was measured reliably, and the condition represented by “Gene regulation” is a defensible explanation. Core concept: Cells control when and where genes are expressed through regulatory proteins and chromatin state. Concept: Cells control when and where genes are expressed through regulatory proteins and chromatin state.
Gene regulation — common trapA change in expression is not automatically a mutation.
Gene regulation — recognize itRecognition cue: Compare mRNA, protein, promoter, and regulatory-factor evidence. Then state the predicted consequence in your own words before looking at the answer choices.
Gene regulation — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? Expression can change without changing the DNA sequence. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
MetabolismMetabolic pathways use linked reactions, energy coupling, and regulated enzymes.
Case: A controlled study compares 29 participants or samples in Group A with 29 in Group B. The groups differ only in the condition represented by “Metabolism”; the measured outcome is 15 units in Group A and 17 units in Group B. What comparison, mechanism, or limitation should you use before interpreting that difference?Answer: The observed difference is 2 units, but interpret it only after checking that the groups were comparable, the outcome was measured reliably, and the condition represented by “Metabolism” is a defensible explanation. Core concept: Metabolic pathways use linked reactions, energy coupling, and regulated enzymes. Concept: Metabolic pathways use linked reactions, energy coupling, and regulated enzymes.
Metabolism — common trapA pathway diagram’s arrows do not always mean every step is irreversible.
Metabolism — recognize itRecognition cue: Track input, output, energy carrier, and rate-limiting step. Then state the predicted consequence in your own words before looking at the answer choices.
Metabolism — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? Identify the pathway step affected when a substrate accumulates or product falls. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
Cellular respirationGlycolysis, the citric-acid cycle, and oxidative phosphorylation extract energy from fuel.
Case: A controlled study compares 29 participants or samples in Group A with 29 in Group B. The groups differ only in the condition represented by “Cellular respiration”; the measured outcome is 11 units in Group A and 14 units in Group B. What comparison, mechanism, or limitation should you use before interpreting that difference?Answer: The observed difference is 3 units, but interpret it only after checking that the groups were comparable, the outcome was measured reliably, and the condition represented by “Cellular respiration” is a defensible explanation. Core concept: Glycolysis, the citric-acid cycle, and oxidative phosphorylation extract energy from fuel. Concept: Glycolysis, the citric-acid cycle, and oxidative phosphorylation extract energy from fuel.
Cellular respiration — common trapOxygen is the final electron acceptor in oxidative phosphorylation, not glycolysis.
Cellular respiration — recognize itRecognition cue: Separate substrate-level from oxidative phosphorylation. Then state the predicted consequence in your own words before looking at the answer choices.
Cellular respiration — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? Use oxygen availability to predict electron-transport and ATP-production changes. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
Immune systemInnate defenses act quickly; adaptive responses use antigen-specific lymphocytes and memory.
Case: A controlled study compares 26 participants or samples in Group A with 26 in Group B. The groups differ only in the condition represented by “Immune system”; the measured outcome is 16 units in Group A and 21 units in Group B. What comparison, mechanism, or limitation should you use before interpreting that difference?Answer: The observed difference is 5 units, but interpret it only after checking that the groups were comparable, the outcome was measured reliably, and the condition represented by “Immune system” is a defensible explanation. Core concept: Innate defenses act quickly; adaptive responses use antigen-specific lymphocytes and memory. Concept: Innate defenses act quickly; adaptive responses use antigen-specific lymphocytes and memory.
Immune system — common trapAntibodies do not directly destroy every infected cell.
Immune system — recognize itRecognition cue: Identify barrier, innate cell, B cell, T cell, and memory response. Then state the predicted consequence in your own words before looking at the answer choices.
Immune system — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? Distinguish antibody-mediated and cell-mediated responses. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
Cardiovascular physiologyCardiac output equals heart rate times stroke volume, and pressure drives flow through vessels.
Case: Two trials keep stroke volume at 70 mL but raise heart rate from 60 to 90 beats/min. In which direction should cardiac output move?Answer: Cardiac output rises from 4.2 L/min to 6.3 L/min because heart rate multiplied by 70 mL determines output. Concept: Cardiac output equals heart rate times stroke volume, and pressure drives flow through vessels.
Cardiovascular physiology — common trapA faster heart rate does not guarantee higher output if stroke volume falls.
Cardiovascular physiology — recognize itRecognition cue: Track rate, volume per beat, pressure, and resistance. Then state the predicted consequence in your own words before looking at the answer choices.
Cardiovascular physiology — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? Use vessel radius, resistance, and pressure differences to predict perfusion. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
Respiratory physiologyVentilation brings air to alveoli and diffusion exchanges gases along partial-pressure gradients.
Case: At high oxygen partial pressure, hemoglobin is already near the plateau of its binding curve. What happens to saturation after a modest further pressure increase?Answer: Saturation changes only a little because the high-pressure region is the plateau of the sigmoidal curve. Concept: Ventilation brings air to alveoli and diffusion exchanges gases along partial-pressure gradients.
Respiratory physiology — common trapVentilation and perfusion are related but not identical.
Respiratory physiology — recognize itRecognition cue: Separate airflow, blood flow, and diffusion. Then state the predicted consequence in your own words before looking at the answer choices.
Respiratory physiology — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? Predict oxygen transfer when surface area, membrane thickness, or gradient changes. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
Renal physiologyNephrons filter plasma and selectively reabsorb or secrete substances to regulate volume and composition.
Case: A controlled study compares 33 participants or samples in Group A with 33 in Group B. The groups differ only in the condition represented by “Renal physiology”; the measured outcome is 10 units in Group A and 12 units in Group B. What comparison, mechanism, or limitation should you use before interpreting that difference?Answer: The observed difference is 2 units, but interpret it only after checking that the groups were comparable, the outcome was measured reliably, and the condition represented by “Renal physiology” is a defensible explanation. Core concept: Nephrons filter plasma and selectively reabsorb or secrete substances to regulate volume and composition. Concept: Nephrons filter plasma and selectively reabsorb or secrete substances to regulate volume and composition.
Renal physiology — common trapFiltration is not the same as excretion.
Renal physiology — recognize itRecognition cue: Track filtrate from glomerulus through nephron segments. Then state the predicted consequence in your own words before looking at the answer choices.
Renal physiology — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? Use hormone effects to predict urine concentration and ion handling. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
Endocrine signalingHormones travel through body fluids and regulate distant targets through specific receptors.
Case: A controlled study compares 40 participants or samples in Group A with 40 in Group B. The groups differ only in the condition represented by “Endocrine signaling”; the measured outcome is 10 units in Group A and 16 units in Group B. What comparison, mechanism, or limitation should you use before interpreting that difference?Answer: The observed difference is 6 units, but interpret it only after checking that the groups were comparable, the outcome was measured reliably, and the condition represented by “Endocrine signaling” is a defensible explanation. Core concept: Hormones travel through body fluids and regulate distant targets through specific receptors. Concept: Hormones travel through body fluids and regulate distant targets through specific receptors.
Endocrine signaling — common trapA hormone’s presence does not prove its target responded.
Endocrine signaling — recognize itRecognition cue: Match hormone, receptor, target tissue, and feedback. Then state the predicted consequence in your own words before looking at the answer choices.
Endocrine signaling — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? Use receptor location and feedback loops to predict response timing. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
Nervous systemNeurons transmit information through electrical changes and chemical synapses.
Case: A controlled study compares 35 participants or samples in Group A with 35 in Group B. The groups differ only in the condition represented by “Nervous system”; the measured outcome is 16 units in Group A and 24 units in Group B. What comparison, mechanism, or limitation should you use before interpreting that difference?Answer: The observed difference is 8 units, but interpret it only after checking that the groups were comparable, the outcome was measured reliably, and the condition represented by “Nervous system” is a defensible explanation. Core concept: Neurons transmit information through electrical changes and chemical synapses. Concept: Neurons transmit information through electrical changes and chemical synapses.
Nervous system — common trapDepolarization and action-potential firing are not identical at every location.
Nervous system — recognize itRecognition cue: Track ion movement and membrane voltage. Then state the predicted consequence in your own words before looking at the answer choices.
Nervous system — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? Predict the effect of ion-channel opening on membrane potential. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
HomeostasisRegulatory systems maintain internal variables near a set range despite disturbances.
Case: A controlled study compares 38 participants or samples in Group A with 38 in Group B. The groups differ only in the condition represented by “Homeostasis”; the measured outcome is 16 units in Group A and 18 units in Group B. What comparison, mechanism, or limitation should you use before interpreting that difference?Answer: The observed difference is 2 units, but interpret it only after checking that the groups were comparable, the outcome was measured reliably, and the condition represented by “Homeostasis” is a defensible explanation. Core concept: Regulatory systems maintain internal variables near a set range despite disturbances. Concept: Regulatory systems maintain internal variables near a set range despite disturbances.
Homeostasis — common trapNegative feedback does not mean the outcome is always negative.
Homeostasis — recognize itRecognition cue: Ask whether the response reduces or amplifies the initial change. Then state the predicted consequence in your own words before looking at the answer choices.
Homeostasis — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? Identify sensor, integrator, effector, and corrective response. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
EvolutionNatural selection changes trait frequencies when heritable variation affects reproductive success.
Case: A controlled study compares 24 participants or samples in Group A with 24 in Group B. The groups differ only in the condition represented by “Evolution”; the measured outcome is 8 units in Group A and 15 units in Group B. What comparison, mechanism, or limitation should you use before interpreting that difference?Answer: The observed difference is 7 units, but interpret it only after checking that the groups were comparable, the outcome was measured reliably, and the condition represented by “Evolution” is a defensible explanation. Core concept: Natural selection changes trait frequencies when heritable variation affects reproductive success. Concept: Natural selection changes trait frequencies when heritable variation affects reproductive success.
Evolution — common trapIndividuals do not evolve because they need a trait.
Evolution — recognize itRecognition cue: Look for heritable variation and differential reproduction. Then state the predicted consequence in your own words before looking at the answer choices.
Evolution — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? Distinguish selection from drift, migration, and mutation. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
Experimental biologyA biological conclusion depends on controls, replication, measurement quality, and appropriate inference.
Case: A controlled study compares 28 participants or samples in Group A with 28 in Group B. The groups differ only in the condition represented by “Experimental biology”; the measured outcome is 12 units in Group A and 18 units in Group B. What comparison, mechanism, or limitation should you use before interpreting that difference?Answer: The observed difference is 6 units, but interpret it only after checking that the groups were comparable, the outcome was measured reliably, and the condition represented by “Experimental biology” is a defensible explanation. Core concept: A biological conclusion depends on controls, replication, measurement quality, and appropriate inference. Concept: A biological conclusion depends on controls, replication, measurement quality, and appropriate inference.
Experimental biology — common trapA statistically significant association does not automatically establish mechanism.
Experimental biology — recognize itRecognition cue: Name the manipulated variable, outcome, comparison, and limitation. Then state the predicted consequence in your own words before looking at the answer choices.
Experimental biology — retrieval promptWhen a passage or data set points to this concept, ask: what variable, mechanism, or comparison would I predict next? Use randomization and matched conditions to isolate treatment effects. Your answer should name the direction, condition, or limitation that makes the prediction defensible.
Biological and Biochemical Foundations Study Online Center · Flashcards
Full-Length Biological and Biochemical Foundations Practice Tests
Two original, independently written forms match the current section question count and timing. Use the PDF for a timed sitting; the TeX source is available for transparent review and local editing.
Practice Test 1Open PDF · TeX source
Practice Test 2Open PDF · TeX source
These are original independent practice forms informed by the public AAMC blueprint. They are not official AAMC questions or score reports.
A USEFUL NEXT STEP
MCAT Biological and Biochemical Foundations: study questions
What can I study in this MCAT Biological and Biochemical Foundations Online Center?
This MCAT Biological and Biochemical Foundations Online Center includes practice, lessons, worksheets, flashcards and review tools. Topics on the page include Mini Tests, Molecules and cells, Genetics and information.
How should I use the MCAT Biological and Biochemical Foundations resources?
Choose a topic or practice activity from this Online Center. Review the linked explanation, try the practice, and use the result to decide what to study next. Check each resource’s directions for its format and access requirements.
Resources from Effortless Math · Editorial standards