Updates and Edits for MCAT® UBooks

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UWorld’s MCAT UBooks deliver the most current information available when published. But exam content and details can change. Our researchers and subject matter experts will post any subject-specific and exam-related updates here to keep your prep aligned with the current AAMC syllabus and the latest scientific research. We will also include corrections and clarifications needed for our Behavioral Science, Biochemistry, Biology, CARS, General Chemistry, Organic Chemistry, and Physics UBooks.

2026⁠–⁠2027 2025⁠–⁠2026

Biology

Biochemistry

General Chemistry

Organic Chemistry

Physics

Behavioral Sciences

CARS

Biology

Updates: 2026-2027 UWorld MCAT Biology UBook

Biology book content updates and corrections from October 2025 – Present

Lesson Number	Page Number(s)	Update Type	Print Book	Digital Book (UBook)
6.3	240	In-line Image	Figure 6.27: “the” is repeated twice in step 2	Figure updated to remove extra “the“

Biochemistry

General Chemistry

Organic Chemistry

Physics

Behavioral Sciences

Updates: 2026-2027 UWorld MCAT Behavioral Science UBook

Behavioral Science book content updates and corrections from October 2025 – Present

Lesson Number	Page Number(s)	Update Type	Print Book	Digital Book (UBook)
2.1	6	Book Text	Does not include operationalization	Added last paragraph to describe operationalization
2.3	8	Book Text	Does not include sampling bias or experimenter bias	Added paragraphs to define sampling bias and experimenter bias
3.2	11	Book Text	Does not include correlation strengths	Added correlation strengths hyperlink
17.2	99	Book Text	Does not include learned helplessness	Added learned helplessness hyperlink
21.1	125	Book Text	Does not include insight	Added last paragraph to define insight
22.1	130	In-line Table	Text states “Occurs before a critical (time-sensitive) period in early life”	Text corrected to “Occurs during a critical (time-sensitive) period early in life”
36.5	207	Book Text	First paragraph: does not define nodes and ties	Added sentence defining nodes and ties
38.1	215	Book Text	Does not include foraging, mate selection, or inclusive fitness	Added paragraphs to define foraging, mate selection, and inclusive fitness
40.2	221	Book Text	Second paragraph: stereotype threat description includes “feels judged based on” and “results in anxiety that negatively impacts”	Description of stereotype threat has been updated to “is at risk of fulfilling” and “leads to impaired”
43.1	240	Book Text	First paragraph: Does not include explanation of educational segregation	Added second paragraph to explain educational segregation

CARS

Biology

Biochemistry

General Chemistry

Organic Chemistry

Physics

Behavioral Sciences

CARS

Biology

Updates: 2025-2026 UWorld MCAT Biology UBook

Biology book content updates and corrections from August 2024 – Present

Lesson Number	Page Number(s)	Update Type	Print Book	Digital Book (UBook)
1.2	10	Book Text	Concept 1.2.03: The second sentence contains information not applicable given our figures	The sentence was removed; the sentence prior was merged to the following paragraph
1.2	12	Book Text	Second paragraph: Contains misleading information regarding condensation reactions	Revised to remove information regarding exergonic processes
2.4	59	In-line Image	Figure 2.31: Two floating labels exist	Figure images that match labels have been added
2.4	64	Book Text	First paragraph: “Proteasomes” is mistakenly spelled as “Proteosomes“	The word “Proteasomes” has been spelled correctly
N/A	69	Table of Contents	Concept 3.1.04 is incorrectly named, and Concept 3.1.05 is missing	Revised to show correct concepts and corresponding names
4.1	91	In-line Image	Figure 4.2: Period follows “ssDNA” next to the bottom left arrow	Period removed
4.1	104	In-line Image	Figure 4.14: double-stranded cDNA in final panel mistakenly contains the base “U“	The base “U” has been replaced with the base “T“
4.3	124	Concept Check	Concept Check 4.3: Contains bullet points for answer choices	Revised bullet points to letters in answer choices so they align with the solution
4.4	133	Book Text	In the third line from the bottom: “plants” is mistakenly spelled as “plans“	The word “plants” has been spelled correctly
4.4	133	Book Text	Last sentence: “death” is mistakenly spelled as “deal“	The word “death” has been spelled correctly
4.4	135	In-line Image	Figure 4.40: The y-axis is mistakenly labeled “Hundreds of millions“	The Y-axis label has been revised to “Millions“
5.2	160	In-line Image	Figure 5.18: Arrows face incorrect directions on the third carrier	Figure updated to correct arrow directions
5.5	209	In-line Image	Figure 5.66: Pseudostratified columnar epithelium image does not clearly show pseudostratification	Figure updated to clearly show pseudostratification
6.3	240	In-line Image	Figure 6.27: “the” is mistakenly listed twice in step 2	Figure updated to single use of “the“
6.3	243	Book Text	Last paragraph incorrectly refers to inverted palindromic repeats rather than inverted repeats	Second sentence of last paragraph has been removed
6.3	244	In-Line Image	Figure 6.31 and figure description include incorrect references to inverted palindromic repeats rather than inverted repeats	Figure 6.31 and figure description updated to remove palindromic references
6.4	255	In-line Image	Figure 6.42: Contains arrow pointing towards RNA being translated that should not be present	Figure updated to remove the arrow
7.2	281	In-line Image	Figure 7.12: “exhibited” is mistakenly spelled as “exhibted“	The word “exhibited” has been spelled correctly
7.2	283	In-line Image	Figure 7.14: The word “phenotype” is partially covered by an image	The image has been moved so that the term is fully visible
7.3	288	In-line Image	Figure 7.18: “SRY” gene name lacks italics	“SRY“ has been italicized
10.2	344	Book Text	The last word on the page mistakenly names “endoderm” rather than the correct “mesoderm“	Updated to replace “endoderm” with “mesoderm“
10.4	359	Book Text	Second paragraph, second sentence: “The embryonic period begins with zygote formation (week two of pregnancy,…”	Updated to “The embryonic period begins with gastrulation (week three of pregnancy,…”
10.5	368	In-line Image	Figure 10.27: “Suppresses” is mistakenly spelled as “Supresses“	The word “Suppresses” has been spelled correctly
11.1	372	Book Text	The last sentence mistakenly contains “cortisol” and “cortical“	Updated to replace “cortisol” with “epinephrine” and “cortical” with “medullary“
11.1	372	In-line Image	Figure 11.1: Mistakenly shows cortisol binding to cell surface receptors	Updated to replace “Cortical” with “Medullary” and “Cortisol” with “Epinephrine“
11.2	385	In-line Image	Figure 11.13: Mistakenly contains hyphen in footnote	Updated to replace hyphen with en dash
11.2	393	In-line Image	Figure 11.19: “blood” is mistakenly spelled as “bood“	The word “blood” has been spelled correctly
11.2	396	In-line Image	Figure 11.22: Catecholamine images do not match in the two panels	Revised to show matching catecholamines
11.2	412	In-line Image	Figure 11.38: Space missing between instances of a number followed by “AM” or “PM”	Revised to add missing spaces
12.1	420	In-line Image	Figure 12.2: “Node of Ranvier” mistakenly in bold text	Bolding removed on “Node of Ranvier“
12.2	429	In-line Image	Figure 12.11: “gates” is incorrectly pluralized	Revised “gates” to “gate“
12.2	432	In-line Image	Figure 12.14: Restoring phase incorrectly extends past the point at which RMP is reached	Updated end of restoring phase to occur when RMP is reached
12.2	436	In-line Image	Figure 12.18: “postsynaptic” is mistakenly spelled as “postynaptic“	The word “postsynaptic” has been spelled correctly
13.1	457	In-line Image	Figure 13.6: Contains two instances each of “O2” and “CO2” without numbers subscripted	Revised chemical formulas to “O₂” and “CO₂“
13.1	480	In-line Image	Table 13.2: three instances of “contractility” mistakenly spelled as “contactility“	The word “contractility” has been spelled correctly
14.2	508	Book Text	“abnormally” is mistakenly spelled as “abnormalllly“	The word “abnormally” has been spelled correctly
15.1	513	Book Text	Last sentence incorrectly states that lingual lipase produces monoglycerides as a product	Text has been updated to “…lingual lipase, which hydrolyzes triglycerides into diglycerides and free fatty acids,…”
15.2	525	In-line Image	Figure 15.11: “detoxification” is mistakenly spelled as “detoxificaion“	The word “detoxification” has been spelled correctly
17.1	562	In-line Image	Figure 17.8: “Acetyl CoA” is incorrectly missing a hyphen in the right panel	Revised to include a hyphen in “Acetyl-CoA“
17.1	565-566	Book Text	In numbered steps, “Pi” does not contain the subscripted “i” (three instances)	Revised to correctly subscript the three instances of “P_i“
17.1	566	Book Text	Two instances of missing superscript for “2+” prior to “Ca“	Revised to correctly superscript the two instances of “Ca²⁺“
17.1	569	Concept Check	Concept Check 17.1: “log” is incorrectly lowercase on the y-axis of the stem graph	Revised to capitalize “Log“
20.1	616	Concept Check	Concept Check 20.1: Neutrophil image is incorrectly aligned	Revised to correctly align the neutrophil image
N/A	637	Appendix	Concept Check 5.3 Solution: A portion of the answer for “Lysosomes” is missing	Text should read: “Lysosomes; carbohydrates cannot be degraded, eliminated, or recycled.”
N/A	639	Appendix	Concept Check 12.2 Solution: Missing state of closed channels for three phases	Digital concept check solution revised to include closed channels

Biochemistry

Updates: 2025-2026 UWorld MCAT Biochemistry UBook

Biochemistry book content updates and corrections from August 2024 – Present

Lesson Number	Page Number(s)	Update Type	Print Book	Digital Book (UBook)
1.1	3	In-line Image	Figure 1.1: The first methylene group in the side chain of arginine is missing its subscript 2	The structure of arginine has been updated to include the missing subscript
1.2	17	In-line Image	Figure 1.27: The figure caption states “The aliphatic amino acids;” however, the image omits glycine	The figure caption has been revised to state “Selected aliphatic amino acids”
3.2	104	Book Text	Figure 3.12: The figure caption states “Agonists bind to receptors but do not cause the normal biological response.”	The figure caption has been updated to state “Antagonists bind to receptors but do not cause the normal biological response.”
4.1	137	In-line Image	Figure 4.7: An arrowhead is missing on the line pointing to “Released products“	The arrowhead has been added to the image
4.2	142	In-line Image	Figure 4.11: Under the Oxidized product molecule, the word product is misspelled as “procuct“	The label has been corrected to spell “product” correctly
4.2	156	Book Text	Final paragraph, final sentence: “However, … enzymes that catalyze these reactiosn are considered isomerases rather than oxidoreductases.”	Updated to: “However, … enzymes that catalyze these reactions are considered isomerases rather than oxidoreductases.”
4.2	159	Concept Check	Concept Check 4.7: The question stem image includes wrong structures for products of a reaction by isomerases	The image has been updated to reflect correct products of catalysis by isomerases
4.4	190	In-line Table	Table 4.6: In the bottom-left cell, chromatography is misspelled as “chromotrography“	The cell has been corrected to spell “chromatography” correctly
5.4	248	In-line Table	Table 5.6: The bottom-right quadrant states “K_M increased” for an uncompetitive-like mixed inhibitor	The bottom-right quadrant has been corrected to state “K_M decreased“
6.1	253	In-line Image	Figure 6.2, left panel: Glucose 6-phosphate is misspelled as “Glucose 6-phosohate“	Glucose 6-phosphate is spelled correctly
9.2	360	In-line Image	Figure 9.19: The line-angle structure of cholesterol is missing one methyl group and one stereochemical designation	The line-angle structure for cholesterol has been corrected
9.3	393	In-line Table	Table 9.1: The structures for several molecules had minor errors	The structures for each of the molecules have been corrected
10.1	401	In-line Table	Table 10.1: The table headers are “Molecule“/” ∆G′° (kJ/mol)“/”ATP Yield…“/”Total energy (kJ)“/”Efficiency…“	Table 10.1 has been revised for clarity, with headers of “Reaction“/” ∆G′°(kJ/mol)“/”Number of reactions per glucose molecule“/”Total energy (kJ)“/”Efficiency…“
11.1	422	Book Text	Paragraph after Figure 11.6: “Aldolase…forms a double bond between carbon 3 and its hydroxyl oxygen….”	The text has been corrected, stating “Aldolase…forms a double bond between carbon 4 of the unsplit molecule and its hydroxyl oxygen….”
11.1	423	In-line Image	Figure 11.8: Fructose 1,6-bisphosphate is mislabeled as “Fructose 1,6-biphosphate“	The label now correctly states “Fructose 1,6-bisphosphate“
11.1	426	In-line Image	Figure 11.4: 1,3-bisphosphoglycerate is mislabeled as “1,3-biphosphoglycerate“	The labels now correctly state “1,3-bisphosphoglycerate“
11.3	453	In-line Image	Figure 11.40: Glyceraldehyde 3-phosphate is mistakenly referred to as “Glyceraldehyde 6-phosphate“	The label for “Glyceraldehyde 3-phosphate” has been corrected
11.3	453	In-line Image	Figure 11.40: The arrows for the oxidative phase proceed from “Glucose,” and only one arrow leads to NADPH production	The arrows now proceed from “Glucose 6-phosphate,” and two arrows lead to NADPH production
11.3	460	In-line Image	Figure 11.49: The enzyme is stated to be “Transketolase“	The enzyme has been corrected to “Transaldolase“
12.1	489	In-line Image	Figure 12.10: The structure for Succinyl-CoA has an extra H attached to the carbonyl carbon of the thioester group	The structure for Succinyl-CoA has been corrected
12.3	513	In-line Image	Figure 12.32: The arrow connecting the ADP molecules to each other incorrectly moves from the matrix to the intermembrane space	The arrow now correctly moves from the intermembrane space to the matrix
13.1	535	In-line Image	Figure 13.23: The reaction describing the production of NADPH via the citrate shuttle is depicted left-to-right	The reaction has been flipped to proceed right-to-left, to better match the process it is being coupled to
13.2	542	Book Text	Final paragraph: A word is missing in the sentence, “…the ammonium…would not excreted but would instead equilibrate…”	The text has been updated to state, “…the ammonium…would not be excreted but would instead equilibrate…”

General Chemistry

Updates: 2025-2026 UWorld MCAT General Chemistry UBook

General Chemistry book content updates and corrections from August 2024 – Present

Lesson Number	Page Number(s)	Update Type	Print Book	Digital Book (UBook)
1.6	53	Book Text	First paragraph: “One atom of zirconium has a mass of 90 amu, which is a very small mass (equivalent to 1.66 × 10⁻²⁴ g), whereas 6.022 × 10⁻²³ atoms (1 mol) of zirconium have a mass of 90 g.”	Updated to: “One atom of zirconium-90 has a mass of 90 amu, which is a very small mass (equivalent to 1.49 × 10⁻²² g), whereas 6.022 × 10²³ atoms (1 mol) of zirconium-90 have a mass of 90 g.”
2.1	66	Book Text	Last paragraph: “Relative comparisons…can made by approximating….”	The text has been updated to state: “Relative comparisons…can be made by approximating….”
2.1	78	In-line Table	Table 2.1: The formula of arsenate is incorrectly written as “AsO₃³⁻“	The formula of arsenate has been corrected to “AsO₄³⁻“
2.2	93	Book Text	First paragraph, second sentence: “As such, sp and sp² hybridization result in an atom with one or two unhybridized p orbitals, respectively.”	Updated to: “As such, sp and sp² hybridization result in an atom with two unhybridized p orbitals or one unhybridized p orbital, respectively.”
2.5	130	Book Text	Second-to-last paragraph: The text could be misconstrued to imply that both reactants are completely consumed simultaneously	The text has been revised to clarify that complete consumption of each reactant is theoretical and should be considered separately
N/A	138	Table of Contents	Concept 6.1.02 is incorrectly spelled “Guy-Lussac’s Law“	Concept 6.1.02 should be spelled as “Gay-Lussac’s Law“
3.4	164	Book Text	Header and first paragraph: Sublimation is misspelled as “sublimination“	“Sublimation” is spelled correctly
3.4	166	Book Text	First paragraph: The word complementary is misspelled as “complimentary“	“Complementary” is spelled correctly
3.4	172	In-line Image	Figure 3.29: The scale for the y-axis (Normal boiling point (°C)) has a range of 0–6	The scale for the y-axis has been updated to have a range of 100–106
5.1	229	Book Text	The example for heterogeneous equilibria is: “2 Cr³⁺(aq) + Cd(s) ⇄ Pb²⁺(aq) + 2 Cr²⁺(aq)”	The example has been updated to: “2 Cr³⁺(aq) + Cd(s) ⇄ Cd²⁺(aq) + 2 Cr²⁺(aq)”
5.4	244	Book Text	First paragraph, second sentence: “Under constant-temperature conditions, this disturbance changes the value of Q (ie, Q no longer equals K_eq).”	Updated to: “This disturbance changes the value of Q (ie, Q no longer equals K_eq under constant-temperature conditions).”
5.4	244	Book Text	Third paragraph, final sentence: “Therefore, removing products or adding reactants shifts the equilibrium position toward reactants, as summarized in Figure 5.12.”	Updated to: “Therefore, adding products or removing reactants shifts the equilibrium position toward reactants, as summarized in Figure 5.12.”
6.1	253	Book Text	Concept 6.1.02 is incorrectly spelled “Guy-Lussac’s Law“	Concept 6.1.02 is correctly spelled as “Gay-Lussac’s Law“
7.1	277	In-line Image	Figure 7.1: The label in the bottom right states the solution is “heterogeneous“	The label has been updated to state that the solution is “homogeneous“
7.1	283	Book Text	The equation for osmolarity was mistakenly displayed as Osmolarity = iM = ^RT/_π	The equation is correctly shown to be Osmolarity = iM = ^π/_RT
7.2	288	In-line Image	Figure 7.6: The middle and right panels incorrectly use the less than (“<“) symbol when relating the ion concentration to K	The symbols have been updated to be equal (“=“) for equilibrium and greater than (“>“) for precipitation
7.2	296	Book Text	The formula showing the equilibrium constant for a gas dissolving into water is incorrectly described as k_H = ^P_X(g)/_{C_X(aq)}	The equation has been corrected to k_H = ^C_X(aq)/_{P_X(g)}
8.2	305	In-line Image	Figure 8.10: The exponent for the bottom number on the y-axis scale is missing, leaving “10⁻“	The exponent has been added, so that the bottom number now reads “10⁻¹⁴“
8.3	310	Book Text	The formula for the acid ionization constant K_a is incorrectly given as: K_a = ^{[H₃ O⁺] [OH⁻]}/_[HA]	The formula for the acid ionization constant K_a is correctly given as: K_a = ^{[H₃ O⁺] [A⁻]}/_[HA]
8.3	311	In-line Image	Figure 8.16: A K_a of 10⁰ is mistakenly shown to correspond to a pK_a value of “1“	The K_a of 10⁰ now correctly corresponds to a pKa value of “0“
8.3	314	Book Text	The figure reference in the third paragraph points to “Figure 8.18,” and the figure reference in the bottom paragraph points to “Figure 8.19“	The figure reference in the third paragraph now points to “Figure 8.19,”and the figure reference in the bottom paragraph now points to “Figure 8.20“
8.3	314	In-line Image	Figure 8.19: A K_b of 10⁰ is mistakenly shown to correspond to a pK_b value of “1“	The K_b of 10⁰ now correctly corresponds to a pK_b value of “0“
8.3	315	In-line Image	Figure 8.20: Top panel, a proton is attached to A^–	The proton has been removed from A^–
8.3	315	Book Text	The figure reference in the second paragraph points to “Figure 8.20“	The figure reference in the second paragraph now points to “Figure 8.21“
8.6	339	Book Text	Last sentence: “The opposite is seen if the analyte is a strong base and a strong base titrant is added.”	The sentence has been updated to state “The opposite is seen if the analyte is a strong base and a strong acid titrant is added.”
8.6	344	In-line Image	Figure 8.45: The x-axis states “Volume of base added (mL)”	The x-axis has been updated to state “Volume of acid added (mL)”
9.2	355	Book Text	Bottom paragraph: “…however, when the S₂O₃ ^2- titrant reduces all the iodine ions (I⁻)…”	Revised to: “…however, when the S₂O₃ ^2- titrant reduces all the iodine atoms to iodide ions (I⁻)…”
9.3	362	Book Text	The text implies that the anode is negatively charged and the cathode is positively charged for every electrochemical cell	The text has been revised to clarify that the anode is negative (and the cathode is positive) only for cells with spontaneous redox reactions (ie, galvanic cells)
9.3	363	In-line Image	Figure 9.8: The electrolytic cell shows a negative charge for the anode and a positive charge for the cathode	The charges of the electrodes for the electrolytic cell have been corrected (anode is positive, cathode is negative)
9.3	364	In-line Image	Figure 9.9: The oxidation half-reaction shows Cr(s) incorrectly oxidizing to “Cu³⁺(aq)“	Cr(s) now correctly oxidizes to “Cr³⁺(aq)“
9.3	365	In-line Table	Table 9.1: The final row shows the reduction of “Mg²⁺” to “Mg” with a standard reduction potential of −1.18 V	The final row has been updated to reflect the reduction of “Mn²⁺” to “Mn” with the given standard reduction potential
9.4	370	Book Text	Concept 9.4.02: References to the thermodynamic variables use standard state designations (eg, ∆G°, E°_cell)	Thermodynamic variables are now presented at non–standard state, as would be appropriate for concentration cells
9.5	374	Book Text	First paragraph: “…Cr³⁺(aq) ions are reduced to form Cd(s) at the cathode (ie, Cd(s) is plated onto the surface of the cathode…”	Updated to: “…Cr³⁺(aq) ions are reduced to form Cr(s) at the cathode (ie, Cr(s) is plated onto the surface of the cathode…”
9.5	375	Book Text	The equation at the top of the page yields grams of “Cd(s)“	The equation has been updated to yields grams of “Cr(s)“
1.3	380	Appendix	Concept Check 1.6: The solution is given as “[Xe]6s²5d¹⁰“	Concept check digital solution corrected to “[Xe]6s²4f¹⁴5d¹⁰“
2.5	382	Appendix	Concept Check 2.27: The solution states “Al(s) is the limiting reactant; 1.50 mol excess O₂(g)“	Concept check digital solution corrected to state O₂(g) is the limiting reactant; 2.00 mol excess Al(s)
5.3	383	Appendix	Concept Check 5.4: The solution states, “The reaction will must shift word the reactants.”	The extra word “will” should be removed: The reaction must shift word the reactants.
5.3	383	Appendix	Concept Check 5.5: The solution states “The reaction is not spontaneous in the forward direction (ΔG > 0).“	Concept check digital solution corrected to state that the reaction is spontaneous in the forward direction (∆G < 0)

Organic Chemistry

Updates: 2025-2026 UWorld MCAT Organic Chemistry UBook

Organic Chemistry book content updates and corrections from August 2024 – Present

Lesson Number	Page Number(s)	Update Type	Print Book	Digital Book (UBook)
1.1	6	Book Text	1.1.03 first paragraph: Extra word “and” appears in the third sentence	Extra word “and” has been removed
1.1	9	In-line Image	Figure 1.6: Point B labels the atoms as “Farther apart“	The atoms under Point B have been relabeled as “Closer together“
1.2	11	Book Text	Concept 1.2.01 First paragraph, last sentence ends “…there is zero probability of electron density.”	The words “probability of” have been removed, so that the sentence ends “…there is zero electron density.”
1.4	19	Book Text	Concept 1.4.01 First paragraph, last sentence ends “…where the probability of electron density is zero.”	The words “probability of” have been removed, so that the sentence ends “…where the electron density is zero.”
1.4	19	In-line Image	Figure 1.19: The y-axes are labeled as “Electron probability (+ or −)“	The y-axes have been re-labeled as “Amplitude“
1.4	20	Book Text	First sentence ends “…amplitude (ie, probability of electron density).”	The parenthetical text has been removed, so that the first sentence ends with “…amplitude.”
1.4	20	In-line Image	Figure 1.20: The y-axes are labeled as “Electron probability (+ or −)“	The y-axes have been re-labeled as “Amplitude“
2.4	39	In-line Image	Figure 2.9: The structure for C₇H₁₆ is missing two carbon atoms	Structure for C₇H₁₆ has been corrected to match its formula
2.5	43	Book Text	First paragraph: “NH₄” is included as the third example of a simple molecule	The third example has been updated to “NH₃“
2.5	43	In-line Image	Figure 2.14: The header for the second column reads “Toluene / Acetyl chloride“	The header for the second column has been simplified to “Reactants“
2.6	52	In-line Image	Figure 2.20: The carbonyl oxygen has an extra lone pair	The extra lone pair on oxygen has been removed
2.7	55	Book Text	First sentence: “This lesson reviews the use of Lewis to represent….”	The sentence has been updated to read “This lesson reviews the use of Lewis (dot) structures to represent….”
2.7	55	In-line Image	Figure 2.22: In the left-most molecule, the bottom-right oxygen atom is mistakenly colored green	The bottom-right oxygen atom of the left-most molecule has been updated to be colored purple
2.7	63	In-line Image	Figure 2.34: The nitrogen atom in structure in the orbital representation of pyridine does not connect to the rest of the structure	The structure in the orbital representation of pyridine has been corrected
2.7	66	In-line Image	Figure 2.38 top panel: “resonance” is mistakenly spelled as “resonace“	The word “resonance” has been spelled correctly
2.8	69	Book Text	Top of the page: Description of aldehydes indicates aldehydes have a carbonyl carbon attached to an alkyl group (R) and a hydrogen atom	Revised to state that the carbonyl carbon is bonded to a hydrogen atom and either another hydrogen atom or an alkyl group (R)
3.1	73	In-line Image	Figure 3.1: Ethyl group on the left molecule in the “Enantiomers” box is missing a hydrogen	Ethyl group structure has been updated
3.3	96	In-line Image	Figure 3.26: Summary statement of the image states that the chiral center is bonded to four different “constituents“	The word “constituents” has been replaced with “substituents“
3.3	96	Book Text	First paragraph: Described the maximal number of stereoisomers in relation to the number of stereocenters	Revised to state that the maximal number of stereoisomers is related more specifically to the number of chiral centers
3.3	111	In-line Image	Figure 3.46: Shows a vertical dashed line bisecting each double bond	The dashed line has been made horizontal
4.2	126	Book Text	Third bullet point: “…based on the lower-value alkene carbon atom.”	The third bullet point has been updated to: “…based on the lower-value alkyne carbon atom.”
4.2	129	Book Text	Second paragraph: The word “molecules” is mistakenly typed as “Cmolecules“	The word “molecules” has been spelled correctly
4.2	130	In-line Image	Figure 4.15: The name for the structure at the top right is misspelled as “1,2-diemethylbenzene“	Figure 4.15: The name for the structure at the top right is spelled correctly as “1,2-dimethylbenzene“
4.2	130	In-line Image	Figure 4.15: The structure for “1-bromo-3-methylbenzyne” is incorrectly named as “1-bromo-2-methylbenzene“	The name for “1-bromo-3-methylbenzene” has been corrected
4.2	131	In-line Image	Figure 4.17: The structure for indole is shows incorrect numbering on its right-hand side	The structure for indole has had its numbering corrected
4.3	133	In-line Image	Figure 4.18: The name for “(2R)-3-methylbutan-2-ol” is mistakenly shown as “(2R)-3-methylbutane-2-ol“	The name for “(2R)-3-methylbutan-2-ol” has been corrected
4.3	136	In-line Image	Figure 4.24: The complex substituent of the middle molecule is named “methylethyl“	The complex substituent of the middle molecule has been updated to “1-methylethyl“
4.3	136	In-line Image	Figure 4.25: The example on the right side shows a structure with a non-IUPAC name of “5-formylpentanoic acid“	The example on the right side of Figure 4.25 has been replaced with “5-formylheptanoic acid“
4.3	139	In-line Image	Figure 4.30: The left molecule depicts 3-(carboxymethyl)heptanoic acid	The left molecule has been updated to depict 3-(carboxymethyl)heptanedioic acid to be more consistent with current IUPAC guidelines
4.3	140	In-line Table	Table 4.7: Final row did not describe the difference in nomenclature for the protonated carboxylic acid and deprotonated carboxylate as a substituent	Table 4.7 final row has been updated to reflect the different nomenclature for carboxylic acid and carboxylates as a substituent
4.3	142	In-line Image	Figure 4.34: The text of the callout box indicates that the methyl group is attached to carbon 4	The text of the callout box has been updated to indicate that the methyl group is attached to carbon 3
4.4	145	In-line Image	Figure 4.37: “substituent” is misspelled as “substitutent“	The word “substituent” has been spelled correctly
4.4	147	In-line Table	Table 4.8: The column headers are listed as “Amine” and “Ammonium“	The column headers have been updated to the more generalized labels “NR₃” and “⊕NR₄“
4.4	148	In-line Image	Figure 4.41: Indole shows incorrect numbering	The numbering for the indole molecule has been corrected
4.4	149	In-line Image	Figure 4.42: Uses “2-ethylbutanediamide” as the rightmost example	The rightmost example has been replaced with “2-methylbutanediamide“
4.5	155	In-line Image	Figure 4.49: Names for the rightmost structure mistakenly labels the “ethylsulfanyl”/”ethylthio” group as “methylsulfanyl“/”methylthio“	Nomenclature for the right-most structure has been corrected to label the group as “ethylsulfanyl“/”ethylthio“
4.6	161	In-line Table	Table 4.10: Substituent term for an amide substituent bonded through the N atom is listed as “amido“	The substituent term has been updated to “alkanamido“
4.6	161	In-line Table	Table 4.10: Suffixes for nitriles is listed as “–onitrile“	The suffix has been updated to “–(e)nitrile“
4.7	164	In-line Image	Figure 4.53: The top row is labeled “Branch prefixes” and implies methyl groups for the sec– and tert– examples	The top row has been updated to “Branching designations” and includes R groups so as to not imply methyl groups when unnecessary
4.7`	167	In-line Table	Table 4.12: The right-most molecule in the amine row is labeled “diisopropylethylamine“	The name for the right-most molecule has been corrected to “ethyldiisopropylamine“
5.1	177	In-line Image	Figure 5.8: Has incorrect labels for the two panels as “Stronger acids“/”Weaker acids“	The labels have been updated to the correct label of “Stronger bases“/”Weaker bases“
5.3	213	In-line Table	Table 5.4: The coloring of the “Good” and “Poor leaving group arrows” results in an ambiguous classification of “Protonated alcohol (Oxonium ion)“	The image has been updated so that “Protonated alcohol (Oxonium ion)” is classified as a “Good leaving group”
5.7	244	In-line Image	Figure 5.80: The gray hydroxyl group has a bond mislabeled as C–H	The bond description has been changed to O–H
5.7	244	In-line Image	Figure 5.80: The compound is mislabeled as a “component” in the note statement	The word “component” has been replaced with “compound“
6.5	268	In-line Table	Table 6.3: Callout box indicating the more stable structure is mistakenly pointing to “penta-1,4-diene“	The label indicating which molecule is more stable is now pointing correctly to “penta-1,3-diene“
6.5	269	In-line Image	Figure 6.5: The LUMO is mistakenly described as the “Lowest occupied molecular orbital“	The text describing LUMO has been updated to “Lowest unoccupied molecular orbital“
6.5	275	In-line Image	Figure 6.12: The description under cyclobutadiene reads “4n + π electrons“	The description has been revised to read “4n π electrons“
6.5	278	In-line Image	Figure 6.15: The description of the electron density being decreased in the bottom panel is mistakenly described with a partial negative charge	The decrease in electron density is correctly described with a partial positive charge
8.2	306	In-line Image	Figure 8.4: The electrophilic carbon atom in the left panel is mistakenly shaded blue	The electrophilic carbon is now shaded orange, indicating its status as an electrophile
8.2	306	In-line Image	Figure 8.5: Footnote describes R as being either an “H” or “alkyl group“	The footnote now describes R as being only an “alkyl group“
8.3	312–313	Book Text	The description of chromic acid oxidation of alcohols includes details of the chromium species	The description has been simplified to focus on the organic species
8.3	313	In-line Image	Figure 8.10: The structure for the Cr (IV) species has the wrong oxidation state of chromium	The mechanism has been simplified to focus on the organic species
8.3	314	In-line Table	Table 8.5: “oxidants” is misspelled as “oxidents“	The word “oxidants” is now spelled correctly
8.3	314	Book Text	Final paragraph: The closing parenthesis is missing for the parenthetical phrase “(in the form of the hydride ion”	The closing parenthesis has been added such that the text reads “(in the form of the hydride ion)”
8.3	315	In-line Image	Figure 8.12: The p-semiquinone structure is missing a lone pair of electrons	The missing lone pair of electrons has been added to the structure of p-semiquinone
8.3	317	In-line Image	Figure 8.13: The indications of substitution preferences are ambiguous	The substitution preferences have been enclosed in callout boxes to indicate that they are the preferences of the electrophile
8.3	317	Book Text	Last paragraph: “…react with Type 2 electrophiles that are…or stabilized by resonance….”	Updated to state: “…react with Type 2 electrophiles that are…or whose corresponding carbocations are stabilized by resonance….”
8.3	320	In-line Image	Figure 8.15: Electrophilic atoms in the sulfonic acid and the sulfonate ester structures are not labeled	The electrophilic atoms are now labeled in their corresponding structures
8.3	325	In-line Image	Figure 8.21: In the bottom panel, the chloride ion is not labeled as a nucleophilic atom	The chloride ion is now labeled as a nucleophilic atom
8.3	327	Book Text	8.3.08 second paragraph: Last sentence describes a dehydration reaction as being the reciprocal process to a condensation reaction	This sentence has been removed (since condensation reactions can remove small molecules other than water)
9.3	341	In-line Image	Figure 9.7: A curved arrow showing electron flow from the C=O pi bond to the oxygen atom is missing	The arrow indicating electron flow has been added
9.3	345	In-line Image	Figure 9.13: The structure of the enamine is incorrect	The structure of the enamine has been updated to show the correct bonding pattern
9.3	353	Book Text	The description of chromic acid oxidation of aldehydes includes details of the chromium species	The description has been simplified to focus on the organic species
9.3	354	In-line Image	Figure 9.20: The structure for the Cr (IV) species has the wrong oxidation state of chromium	The mechanism has been simplified to focus on the organic species
9.4	359	In-line Image	Figure 9.25: “electrophile” is misspelled as “electophile” in the top panel’s title	The word “electrophile” has been spelled correctly
9.4	365	In-line Image	Figure 9.34: Several bonds point to R groups	The bonds have been changed so that they point to an unspecified substituent
9.4	369	In-line Image	Figure 9.39: Top panel, the thermodynamic enolate product is missing its partial negative charges	The partial negative charges have been added
9.4	371	In-line Image	Figure 9.41: A positive charge is missing from the sodium ion, and the electrophilic R’ group in the top panel is colored incorrectly	The positive charge on the sodium ion has been added, and the R’ group has been colored correctly to indicate its electrophilic status
9.4	376	In-line Image	Figure 9.50: Top panel is missing a curved, electron flow arrow from the bond between HA to A. In the bottom panel, the leftmost resonance structure has an extra bond to H from the nucleophilic atom.	The electron flow arrow has been added, and the extraneous bond has been removed
9.4	378	In-line Image	Figure 9.53: 2,2-dimethylpropanal mistakenly labels the alpha carbon as the electrophilic atom	The electrophilic atom is now correctly shown to be the carbonyl carbon
9.4	382	Book Text	Final paragraph: Final sentence states “…producing a β-substituted carbonyl derivative…”	Updated to state “…producing a carbonyl derivative with a new group at the β position…”
9.4	382	In-line Image	Figure 9.57: The key mislabels purple shading as “Atoms lost in byproduct“	The key correctly identifies purple shading as “Groups added“
9.4	383	In-line Image	Figure 9.58: The key mislabels purple shading as “Atoms lost in byproduct“	The key correctly identifies purple shading as “Groups added“
9.4	385	In-line Image	Figure 9.59: In 1,3-dicarbonyl the bottom carbonyl oxygen is mislabeled with coloring indicating it is a nucleophilic atom	The carbonyl oxygen is correctly colored to be an atom lost in byproduct
9.4	386	In-line Image	Figure 9.60: A curved electron flow arrow is missing pointing from the H to the alpha carbon in the Michael adduct	The electron flow arrow has been added
11.1	421	In-line Image	Figure 11.3: The left resonance structure is missing an R group	The R group has been added
11.1	424	In-line Table	Table 11.1: Top-right cell, the units for Boiling point is given as “C°“	The units for Boiling point have been updated to “°C“
11.2	427	In-line Image	Figure 11.6: The anhydride mislabels the R’ group as a heteroatom	The R’ group is no longer marked as a heteroatom
11.3	440	In-line Image	Figure 11.16: Some carboxylic acid derivatives are faded	All carboxylic acid derivatives are shown with full color saturation
12.1	445	In-line Image	Figure 12.1: The aniline and amide nitrogens are mistakenly described as having four electron domains	The aniline and amide nitrogens are now described as having three domains due to resonance
14.1	517	In-line Image	Figure 14.2: There is an unlabeled pOH scale shown	The pOH scale has been removed
14.3	528	In-line Image	Figure 14.12: The lower-left box is titled “Mass spectroscopy” and lists the wavelength range for x-rays as being from “0.1 nm – 10 nm“	The lower left box has been updated so that its title reads “Mass spectrometry” and the wavelength range is “0.01 nm – 10 nm“
14.4	531	Book Text	First paragraph: The second sentence states “The sample source enters the ionization chamber…”	The word “source” has been removed, so the second sentence states “The sample enters the ionization chamber…”
14.5	550	In-line Image	Figure 14.32: The local minima is abbreviated incorrectly as λ_max	Local minima are now correctly abbreviated as λ_min
14.5	553	In-line Image	Figure 14.34: The local minima is abbreviated incorrectly as λ_max	Local minima are now correctly abbreviated as λ_min
14.6	564	In-line Table	Table 14.5: The bottom row for the benzene or phenyl ring mistakenly shows a C≡C triple bond stretch	The bottom row now correctly shows a C=C double bond stretch
14.7	581	In-line Image	Figure 14.59: Arrows for electron movement are moving in the wrong direction to induce the magnetic fields	The direction of electron movement now moves in the correct direction
3.3	593	Appendix	Concept Check 3.8: The depicted line-angle structure shows a molecule with an S configuration	Concept check digital solution corrected to show a molecule with an R configuration

Physics

Updates: 2025-2026 UWorld MCAT Physics UBook

Physics book content updates and corrections from August 2024 – Present

Lesson Number	Page Number(s)	Update Type	Print Book	Digital Book (UBook)
1.1	7	Book Text	Concept Check 1.3: The text “and what the magnitude” is incorrect	Revised to “and what is the magnitude”
1.2	9	In-line Image	Figure 1.4: Variables “r_f” and “r_i” incorrectly labeled as “Initial position” and ” Final position“	Labels for “r_i” corrected to “Initial position” and “r_f” corrected to “Final position“
1.2	11	Book Text	Second paragraph: Statement “as t goes to zero” is incorrect	Statement has been corrected to “as Δt goes to zero“
1.2	13	Book Text	First paragraph: Extra word “only” appears in the second sentence	Revised to “motion in only one dimension“
1.2	22	In-line Image	Figure 1.18: The text “whether it dropped vertically” is incorrect	The text has been corrected to “whether it is dropped vertically”
1.2	23	In-line Image	Figure 1.19: Arrow for v_y in the legend has a solid line	The solid line has been replaced with a dashed line
1.3	29	Book Text	The first pair of equations have “0” above and below summation symbols	Equations corrected by removing extra 0s
1.3	40	Book Text	The first equation “F_a + F_T = ma_x” is incorrect	Equation corrected to “F_a – F_T = ma_x“
1.4	49	In-line Image	Concept Check 1.17: In the figure, the label “COM” is incorrect	Label replaced with “CM “
1.4	52	In-line Image	Figure 1.49: Label “Clockwise (CCW)” in upper right corner is incorrect	Label replaced with “Clockwise (CW)“
1.5	61	In-line Image	Figure 1.57: The second equation for “W” is incorrect	The second equation for “W” has been corrected
3.1	118	Book Text	Near the middle of the page: Extra words “a particle” appears	Revised to “between two identical particles“
3.2	136	Book Text	Concept Check 3.9: The text “Three resistors” is incorrect	Revised to “Four resistors“
3.2	136	Book Text	Concept Check 3.10: The text “resistance of the battery” is incorrect	Revised to “resistance of the circuit“
4.4	227	Book Text	Second sentence: Statement “f = +10 mm and o = +15 mm” is incorrect	Revised to “f = +15 mm and o = +10 mm“
4.4	227	Book Text	Last paragraph: The text “o = 10o = 10 mm” is incorrect	Revised to “o = 10 mm“
4.4	230	In-line Image	Figure 4.72: “Chromatic” is misspelled	The spelling of “Chromatic” has been corrected
4.4	231	In-line Image	Figure 4.73: Incorrectly shows red light focusing closer to the lens	Revised to show blue light focusing closer to the lens
5.2	250	Book Text	Last paragraph: The text “decreasing volume (ΔV > 0)” is incorrect	The text has been corrected to “decreasing volume (ΔV < 0)”
5.5	280	In-line Image	Figure 5.35: Variable “ΔU_p” is listed twice in the bulleted list	Second “ΔU_P” has been corrected to “ΔU_V”
Appendix	284	Book Text	Concept Check 1.1: “6 × 10^-9 m” is incorrect	Revised to ” 6 × 10^-7m“
Appendix	284	Book Text	Concept Check 1.16: “16 N/m” is incorrect	Revised to “10 N/m“

Behavioral Sciences

Updates: 2025-2026 UWorld MCAT Behavioral Science UBook

Behavioral Science book content updates and corrections from August 2024 – Present

Lesson Number	Page Number(s)	Update Type	Print Book	Digital Book (UBook)
4.2	24	In-line Image	Figure 4.11: Shows Na⁺ and K⁺ moving through the same ion channel	Revised so that two ion channels are shown
4.2	26	In-line Image	Figure 4.13: Receptors in the two panels appear the same, and there is an extraneous period	The receptors are differentiated, and the extraneous period has been removed
4.2	26	Book Text	First paragraph: The abbreviation “CNS” appears in the second sentence.	The words “central nervous system (CNS)” have been spelled out in the second sentence.
4.3	31	Book Text	Third paragraph: Sentence includes an extra “from the motor cortex“	The description has been corrected to remove the extra “from the motor cortex“
7.1	42	Book Text	EEG bullet point: Description states “Because action potentials involve a sequence of shifts“	Description has been updated to read “Because depolarization involves a shift“
8.1	47	In-line Image	Figure 8.1: Text states “a strong garbage smell (ie, sensory stimulus) becomes less noticeable over time.“	The text has been corrected to “an individual is less able to detect a strong garbage smell (ie, sensory stimulus) over time.“
8.2	50	In-line Image	Figure 8.4: Shows auditory nerve label before the spiral ganglion	Replacing with newer image that has the auditory nerve label appear after the spiral ganglion
11.2	63	Book Text	Second paragraph: Frequency is described as “the length of sound waves“	Description of frequency has been corrected to “wavelengths per second“
11.2	64	In-line Image	Figure 11.3: Frequency is described as “(ie, length)”	Description has been corrected to “(ie, waves per second)”
41.4	230	Book Text	Concept Title: “41.4.02” incorrectly numbered as “41.4.01“	Concept “41.4.02” has been numbered correctly

CARS

Updates: 2025-2026 UWorld MCAT CARS UBook

CARS book content updates and corrections from August 2024 – Present

Lesson Number	Page Number(s)	Update Type	Print Book	Digital Book (UBook)
5.4	94	Book Text	The first paragraph in the right-hand column: text “was initially used for different purposes” mistakenly in bold	Removed bolding
6.1	138	Book Text	The last sentence in the right-hand column: says, “Statement 3 is a conclusion that the author draws from statements 1 and 2.”	Capitalized the word “Statements”
6.1	148	Book Text	P3 Excerpt and P5 Excerpt: Both end in periods, leaving it unclear that there is more to those paragraphs.	Added ellipses (….) to P3 and P5 excerpts, indicating that part of each paragraph has been omitted.
6.2	160	Book Text	First paragraph: says, “This question asks you to…its main topic, the telegraph or Victorian Internet.”	Changed to say, “This question asks you to…the passage’s main topic, the telegraph or Victorian Internet.”
6.6	234	Book Text	The second line in the question box: says “Strategy-based Explanations”	Changed to singular “Strategy-based Explanation”
6.6	242	Book Text	The second line in the question box: says “Strategy-based Explanations”	Changed to singular “Strategy-based Explanation”
7.4	299	Book Text	Title: says “RWT Subskill 3d…”	Changed to say “RBT Subskill 3d…”
7.4	300	Book Text	Step 1 box—first sentence of second paragraph: says “….Marina Warrner….”	Deleted extra ‘r’ in Warner‘s name.
7.4	301	Book Text	Grey box, third line: says “We now look at three examples…”	Changed to say, “We now look at five examples…”
7.4	322	Book Text	Right-hand column: Headings for Choice C: and Choice B: should not have colons.	Removed colons from headings