Test d'entraînement DAT
Les questions du test restent en anglais.
Voici un échantillon gratuit de 15 questions pour le Dental Admission Test, l'examen d'admission en école dentaire aux États-Unis, rédigé par l'équipe StudyPDF. Il suit la forme du vrai examen : biologie, chimie générale et chimie organique pour le Survey of the Natural Sciences, deux questions sur le raisonnement derrière les tâches du Perceptual Ability Test, trois courts textes de lecture et quatre questions quantitatives. Réponds aux 15 questions, puis regarde ton score et lis l'explication de chaque question.
During which phase of mitosis do the sister chromatids separate and begin moving toward opposite poles?
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Les 15 questions en un coup d'œil
Tu préfères lire avant de jouer ? Toutes les questions de l'échantillon sont listées ci-dessous. Les réponses et les explications restent repliées tant que tu ne les ouvres pas.
1. During which phase of mitosis do the sister chromatids separate and begin moving toward opposite poles?
- A. Prophase
- B. Metaphase
- C. Anaphase
- D. Telophase
Voir la réponse et l'explication
Réponse : C. Anaphase
Metaphase is the lineup, with the chromosomes held at the middle of the cell by spindle fibers from both poles. Anaphase begins when the protein holding the sister chromatids together is cut, so each chromatid is pulled away and now counts as its own chromosome. Telophase is the cleanup, when nuclear envelopes reform around the two new sets.
2. Which of the following are true of prokaryotic cells?
Coche toutes les bonnes réponses.
- A. They have no membrane bound nucleus
- B. Their genome is usually a single circular chromosome sitting in the nucleoid region
- C. They build proteins on ribosomes
- D. They divide by mitosis
- E. They carry out aerobic respiration inside mitochondria
Voir la réponse et l'explication
Réponse : A. They have no membrane bound nucleus, B. Their genome is usually a single circular chromosome sitting in the nucleoid region, C. They build proteins on ribosomes
Prokaryotes have no nucleus and no membrane bound organelles, so their DNA sits loose in a region called the nucleoid, usually as one circular chromosome plus optional plasmids. They do have ribosomes, because every cell needs them to make protein, though prokaryotic ribosomes are smaller than eukaryotic ones and that difference is what several antibiotics exploit. They divide by binary fission rather than mitosis, and the enzymes of aerobic respiration sit in the plasma membrane because there are no mitochondria.
3. Moving from left to right across a period of the periodic table, atomic radius generally:
- A. increases, because each atom holds more electrons
- B. decreases, because the growing nuclear charge pulls the same shell in tighter
- C. stays about the same, because the principal energy level does not change
- D. increases, because inner electrons shield the outer ones more effectively
Voir la réponse et l'explication
Réponse : B. decreases, because the growing nuclear charge pulls the same shell in tighter
Across a period, protons are added to the nucleus while the new electrons go into the same principal energy level, so shielding barely changes and the effective nuclear charge felt by the outer electrons climbs. That stronger pull draws the whole electron cloud in, so the radius shrinks. Down a group the opposite happens, because each step adds a whole new shell and that outweighs the extra protons.
4. Complete the sentence.
At 0 degrees Celsius and 1 atmosphere of pressure, one mole of an ideal gas occupies about _____ liters.
Options pour le trou 1 : 11.2, 22.4, 44.8, 62.4
Voir la réponse et l'explication
Réponse : 22.4
Rearranging PV equals nRT gives V equal to nRT over P, and with n as 1 mole, R as 0.0821 liter atmospheres per mole kelvin and T as 273 kelvin, the volume comes out near 22.4 liters. The useful part is that the ideal gas law never mentions the identity of the gas, so a mole of helium and a mole of carbon dioxide occupy the same volume under the same conditions. Change the temperature or the pressure and that 22.4 changes with it, which is why the conditions have to be stated.
5. An SN2 reaction proceeds fastest with which substrate?
- A. A primary alkyl halide
- B. A secondary alkyl halide with two bulky neighboring groups
- C. A tertiary alkyl halide
- D. A carbon bonded to four other carbon atoms
Voir la réponse et l'explication
Réponse : A. A primary alkyl halide
SN2 happens in one step, with the nucleophile attacking the back side of the carbon at the same moment the leaving group departs. Anything crowding that back side slows it down, so the least substituted carbon reacts fastest and the rate order runs primary, then secondary, then tertiary. Tertiary halides go the other route, SN1, because they form a relatively stable carbocation, and a carbon already bonded to four carbons has no leaving group to lose in the first place.
6. Complete the sentence.
A molecule with 3 stereocenters and no internal plane of symmetry has at most _____ stereoisomers, and each one of those has exactly _____ enantiomer.
Options pour le trou 1 : 3, 6, 8, 9
Options pour le trou 2 : 0, 1, 2, 3
Voir la réponse et l'explication
Réponse : 8, 1
Each stereocenter can be set two ways, so n stereocenters give a maximum of 2 to the power of n stereoisomers, and 2 cubed is 8. An enantiomer is the complete mirror image, meaning every stereocenter is inverted, so any structure has one and only one. Every other member of the set is a diastereomer. The word maximum matters, because internal symmetry can make one structure identical to its own mirror image, a meso compound, which cuts the real count below 2 to the n.
7. A solid block is built from 8 identical cubes stacked 2 by 2 by 2. The entire outside of the block, including the bottom, is painted. How many of the 8 cubes have exactly 3 painted faces?
- A. 0
- B. 4
- C. 6
- D. 8
Voir la réponse et l'explication
Réponse : D. 8
In a 2 by 2 by 2 block every small cube sits at a corner of the big cube, and a corner exposes exactly three faces, so all 8 qualify. The general logic is worth holding onto: in a 3 by 3 by 3 painted on every side, the 8 corners show 3 faces, the 12 edge cubes show 2, the 6 face centers show 1 and the single buried cube shows none. Note that the real cube counting subtest shows you a picture and normally leaves the bottom unpainted, so read the on-screen instructions before you start counting.
8. A square sheet of paper is folded in half, then folded in half again along the other direction. A single hole is punched through all the layers, away from any crease. Which statements are true once the sheet is unfolded?
Coche toutes les bonnes réponses.
- A. The unfolded sheet has four holes
- B. Each fold doubles the number of holes a single punch produces
- C. The holes sit symmetrically about the creases
- D. The unfolded sheet has one hole
- E. The number of holes does not depend on how many times the paper was folded
Voir la réponse et l'explication
Réponse : A. The unfolded sheet has four holes, B. Each fold doubles the number of holes a single punch produces, C. The holes sit symmetrically about the creases
Two folds stack four layers of paper, and one punch goes through all four, so unfolding reveals four holes. Each crease behaves like a mirror, which is why the punched hole reappears reflected across every fold line and the final pattern is symmetric about both creases. Reasoning it out this way is the fast route on the real hole punching subtest, which is visual: it shows you a folding sequence and asks you to pick the resulting pattern on a grid, so practice it with actual diagrams.
9. Read the passage, then answer the question. Tooth enamel is the hardest tissue in the human body, and it is built almost entirely from a mineral called hydroxyapatite. Unlike bone, mature enamel contains no living cells, so once it is formed it cannot grow new tissue the way a fracture in bone knits itself back together. What enamel can do is trade minerals with the fluid sitting on it. When the mouth turns acidic, calcium and phosphate leave the surface. When that acid is buffered away, the same ions can move back in and rebuild the damaged crystal, a process called remineralization. According to the passage, why can enamel not repair itself the way bone does?
- A. Enamel is softer than bone
- B. Mature enamel contains no living cells
- C. Enamel is not made of mineral
- D. Enamel never loses calcium or phosphate
Voir la réponse et l'explication
Réponse : B. Mature enamel contains no living cells
The passage draws the contrast in one sentence: bone heals because it is living tissue, and mature enamel has no cells to do that work. Remineralization is a chemical exchange of ions, not cellular repair, which is exactly why the passage describes it as rebuilding a crystal rather than growing tissue. DAT reading rewards answers you can put a finger on in the text, and the other three options either contradict the passage or are never mentioned.
10. Read the passage, then answer the question. A biofilm is a community of microorganisms stuck to a surface inside a layer of material the cells secrete themselves. Dental plaque is the example most people meet daily. Within hours of a cleaning, proteins from saliva coat the tooth and form a thin film, and the first bacteria to arrive attach to that film rather than to the enamel itself. Later species then attach to the earlier ones. Because the secreted layer slows the movement of antimicrobial agents, and because cells inside a biofilm behave differently from free floating ones, a mature biofilm is much harder to kill than the same species grown loose in liquid. Which statements are supported by the passage?
Coche toutes les bonnes réponses.
- A. The first bacteria attach to a film of salivary protein rather than directly to enamel
- B. A mature biofilm resists antimicrobial agents better than the same bacteria growing loose in liquid
- C. The bacteria in a biofilm produce the material that surrounds them
- D. Plaque takes several weeks to start forming after a cleaning
- E. Every species in plaque attaches to the tooth at the same moment
Voir la réponse et l'explication
Réponse : A. The first bacteria attach to a film of salivary protein rather than directly to enamel, B. A mature biofilm resists antimicrobial agents better than the same bacteria growing loose in liquid, C. The bacteria in a biofilm produce the material that surrounds them
The first three restate the passage: the salivary film comes first, the surrounding layer is secreted by the cells themselves, and the passage gives two reasons a mature biofilm resists antimicrobials. The other two are contradicted. The passage says the film appears within hours, not weeks, and it describes attachment as a sequence in which later species attach to earlier ones. On a select all that apply item, check each option against the text separately rather than picking the ones that feel right together.
11. Read the passage, then answer the question. Saliva does more than moisten food. It carries bicarbonate and phosphate, which neutralize acid, and it washes fermentable sugar away from the tooth surface. After a sugary drink, plaque bacteria produce acid within minutes and the pH near the enamel drops. Saliva then pulls that pH back up over the following twenty to sixty minutes. That recovery window is why dentists pay more attention to how often a person sips a sweet drink than to how large the drink is. Ten sips spread across an afternoon hold the surface at a low pH far longer than the same volume swallowed at once. The passage suggests that the greatest risk to enamel comes from:
- A. the total volume of sugary drink consumed
- B. the concentration of bicarbonate in saliva
- C. how frequently a sugary drink is sipped
- D. swallowing a sugary drink quickly in one sitting
Voir la réponse et l'explication
Réponse : C. how frequently a sugary drink is sipped
The passage ties damage to how long the surface stays at a low pH, and it says saliva needs twenty to sixty minutes to recover. Frequent sipping restarts the acid drop before that recovery finishes, so the surface spends more total time acidic even though the volume is unchanged. The last option is the one the passage explicitly compares against and rejects. Inference questions still have to rest on the text, so trace the chain of sentences that gets you there.
12. A dental material is mixed from powder and water in a 2 to 5 ratio by weight. How many grams of powder are needed to make 350 grams of mixture?
- A. 100 grams
- B. 140 grams
- C. 175 grams
- D. 250 grams
Voir la réponse et l'explication
Réponse : A. 100 grams
A 2 to 5 ratio means the mixture splits into 7 equal parts, 2 of them powder and 5 of them water, so the powder is 2 sevenths of the total. Two sevenths of 350 is 100 grams, leaving 250 grams of water. The common trap is treating 2 to 5 as 2 out of 5 and answering 140. Ratios compare the parts to each other, and you have to add them before you compare either one to the whole.
13. A bag holds 4 red, 3 blue and 5 green marbles. Two marbles are drawn without replacement. What is the probability that both are green?
- A. 25/144
- B. 5/36
- C. 1/6
- D. 5/33
Voir la réponse et l'explication
Réponse : D. 5/33
There are 12 marbles, so the first draw is green with probability 5 over 12. Because the marble is not replaced, the second draw is green with probability 4 over 11, since only 4 green marbles remain out of 11. Multiplying gives 20 over 132, which reduces to 5 over 33. The 25 over 144 answer is what you get if you replace the first marble, so read for the words with or without replacement before you set up the fractions.
14. Complete the sentence.
A solution is 15 percent salt by weight, so a 40 gram sample of that solution contains _____ grams of salt.
Options pour le trou 1 : 6, 15, 24, 40
Voir la réponse et l'explication
Réponse : 6
Percent means parts per hundred, so 15 percent is the decimal 0.15, and 0.15 times 40 gives 6 grams. The other 34 grams are water. The step people skip is checking what the percentage is a percentage of, because by weight means the 40 grams is the total mass of the solution, not the mass of the water it was dissolved into.
15. If 3x minus 7 equals 2x plus 5, what is the value of x squared?
- A. 25
- B. 121
- C. 144
- D. 169
Voir la réponse et l'explication
Réponse : C. 144
Subtract 2x from both sides to get x minus 7 equals 5, then add 7 to both sides to get x equal to 12, so x squared is 144. Two step questions like this one punish anyone who solves for x and stops, because 12 will not be an option and the wrong habit is to grab whatever looks close. Read the last clause of the question again before you pick.
Ce que te demande vraiment le DAT
Le Dental Admission Test est un examen sur ordinateur, propriété de l'American Dental Association et passé dans un centre de test aux États-Unis. Il comporte quatre parties. Le Survey of the Natural Sciences te donne 100 questions en 90 minutes, réparties en 40 de biologie, 30 de chimie générale et 30 de chimie organique. Le Perceptual Ability Test te donne 90 questions en 60 minutes. Le Reading Comprehension te donne 50 questions en 60 minutes. Le Quantitative Reasoning te donne 40 questions en 45 minutes. Avec la pause facultative et le questionnaire facultatif d'après-test, le rendez-vous dure un peu plus de cinq heures.
Les résultats sont rendus en notes d'échelle de 1 à 30, et l'ADA décrit un 19 comme à peu près la performance moyenne au niveau national. Tu obtiens une note distincte pour la biologie, la chimie générale, la chimie organique, la compréhension écrite, le raisonnement quantitatif et le Perceptual Ability Test. L'Academic Average est la moyenne arrondie des cinq notes académiques, et la note perceptive en est volontairement exclue, le PAT se lit donc à part. C'est pour ça que les écoles dentaires regardent surtout ces deux nombres. Ta note dépend du nombre de bonnes réponses, il n'y a donc aucune raison d'en laisser une vide.
Tout le reste bouge. Les frais, la fréquence à laquelle tu peux repasser l'examen, le délai entre deux tentatives, ce que tu peux apporter dans la salle et les outils à l'écran dont tu disposes pendant la section quantitative sont fixés par l'ADA et révisés. Lis le guide du candidat DAT en vigueur sur ada.org plutôt que de te fier à un vieux livre de préparation, ou à cette page.
Comment utiliser cet échantillon
Le vrai DAT compte 280 questions réparties sur quatre sections. Quinze ne peuvent pas remplacer ça, et cet échantillon ne cherche pas à le faire. Ce qu'il peut faire, c'est te montrer laquelle des quatre parties est la plus fragile avant que tu ne construises un plan de révision autour de la mauvaise. Le mélange ici est de six questions de sciences naturelles, deux sur le raisonnement perceptif, trois textes de lecture et quatre questions quantitatives.
Les questions perceptives demandent un avertissement. Le vrai Perceptual Ability Test est entièrement visuel : trous et ouvertures, reconnaissance des vues de dessus, de face et de profil, classement d'angles, perforation de papier, comptage de cubes et pliage de motifs. Une page de texte ne peut pas dessiner ça, et simuler une image avec des mots t'apprendrait de mauvais réflexes. Les deux questions perceptives ici testent donc plutôt les règles et le raisonnement derrière deux de ces tâches. Entraîne-toi à la section elle-même avec de vrais schémas, parce que la vitesse au PAT vient d'une reconnaissance de formes qui se construit uniquement en regardant.
Fais-le d'une traite, sans notes, puis lis toutes les explications, y compris celles des questions que tu as réussies. Traite une mauvaise réponse comme un thème plutôt que comme un fait isolé. Tout ici a été écrit par l'équipe StudyPDF à partir du plan de contenu DAT publié. Ce ne sont pas des questions de l'ADA, StudyPDF n'est pas affilié à l'American Dental Association, et rien sur cette page n'est un conseil dentaire ou médical. C'est de l'entraînement à l'examen.
Comment StudyPDF crée des tests complets à partir de ton propre matériel
Quinze questions peuvent te désigner un point faible. Elles ne peuvent pas te préparer à un examen de 280 questions, et une banque générique correspond rarement à la chimie organique que ton professeur a vraiment mise en avant ni à la biologie à laquelle ton livre DAT consacre quarante pages.
StudyPDF part plutôt de ton matériel. Importe ton livre de préparation au DAT, tes notes de chimie générale, tes fiches de réactions organiques ou les diapos de ton cursus de biologie, et Bo, l'agent de révision, crée des tests d'entraînement complets à partir de ces pages précises. Chaque question est ancrée dans ce que tu as importé, et chaque explication renvoie à l'endroit d'où vient la réponse, tu peux donc aller droit à la source quand quelque chose te semble faux. Génère un nouveau test quand tu veux, restreins-le à un seul domaine comme la stéréochimie ou les équilibres acido-basiques, et suis les concepts que tu rates sans arrêt.
Tu n'as pas besoin de fichier pour commencer. Si tu n'as rien à importer, nomme plutôt un thème, par exemple le métabolisme des glucides ou les mécanismes réactionnels, et Bo écrit un test d'entraînement dessus. Commencer est gratuit.
Rédigé par l'équipe StudyPDF. Mis à jour le 2026-08-19.