Test di esercitazione DAT

Tutti i quiz di Medicina e farmacia

• Test di esercitazione · 15 domande

  Test di esercitazione MCAT

• Test di esercitazione · 15 domande

  Domande di esercitazione NAPLEX

• Test di esercitazione · 15 domande

  Domande di esercitazione MCAT

Vedi tutti →

Crea il tuo

Carica il tuo libro, le slide o i tuoi appunti, oppure di' a Bo cosa vuoi studiare. Per iniziare non serve nessun documento.

Crea il mio test

Tutte le 15 domande a colpo d'occhio

Preferisci leggere prima di iniziare? Qui sotto trovi tutte le domande del test. Risposte e spiegazioni restano chiuse finché non le apri.

1. 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
   Mostra risposta e spiegazione

   Risposta: 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. 2. Which of the following are true of prokaryotic cells?

   Seleziona tutte le risposte corrette.

   • 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
   Mostra risposta e spiegazione

   Risposta: 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. 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
   Mostra risposta e spiegazione

   Risposta: 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. 4. Complete the sentence.

   At 0 degrees Celsius and 1 atmosphere of pressure, one mole of an ideal gas occupies about _____ liters.

   Opzioni per lo spazio 1: 11.2, 22.4, 44.8, 62.4

   Mostra risposta e spiegazione

   Risposta: 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. 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
   Mostra risposta e spiegazione

   Risposta: 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. 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.

   Opzioni per lo spazio 1: 3, 6, 8, 9

   Opzioni per lo spazio 2: 0, 1, 2, 3

   Mostra risposta e spiegazione

   Risposta: 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. 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
   Mostra risposta e spiegazione

   Risposta: 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. 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?

   Seleziona tutte le risposte corrette.

   • 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
   Mostra risposta e spiegazione

   Risposta: 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. 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
   Mostra risposta e spiegazione

   Risposta: 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. 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?

    Seleziona tutte le risposte corrette.

    • 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
    Mostra risposta e spiegazione

    Risposta: 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. 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
    Mostra risposta e spiegazione

    Risposta: 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. 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
    Mostra risposta e spiegazione

    Risposta: 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. 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
    Mostra risposta e spiegazione

    Risposta: 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. 14. Complete the sentence.

    A solution is 15 percent salt by weight, so a 40 gram sample of that solution contains _____ grams of salt.

    Opzioni per lo spazio 1: 6, 15, 24, 40

    Mostra risposta e spiegazione

    Risposta: 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. 15. If 3x minus 7 equals 2x plus 5, what is the value of x squared?

    • A. 25
    • B. 121
    • C. 144
    • D. 169
    Mostra risposta e spiegazione

    Risposta: 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.

Cosa ti chiede davvero il DAT

Il Dental Admission Test è un esame al computer di proprietà dell'American Dental Association che si sostiene in un centro d'esame negli Stati Uniti. Ha quattro parti. Il Survey of the Natural Sciences ti dà 100 domande in 90 minuti, divise in 40 di biologia, 30 di chimica generale e 30 di chimica organica. Il Perceptual Ability Test ti dà 90 domande in 60 minuti. Reading Comprehension ti dà 50 domande in 60 minuti. Quantitative Reasoning ti dà 40 domande in 45 minuti. Con la pausa facoltativa e il questionario facoltativo di fine test, l'appuntamento dura poco più di cinque ore.

I punteggi si comunicano come punteggi in scala da 1 a 30, e l'ADA descrive un 19 come una prestazione all'incirca nella media nazionale. Ricevi un punteggio separato per biologia, chimica generale, chimica organica, reading comprehension, quantitative reasoning e Perceptual Ability Test. L'Academic Average è la media arrotondata dei cinque punteggi accademici, e il punteggio percettivo ne viene lasciato fuori di proposito, così il PAT si legge da solo. È per questo che le facoltà di odontoiatria statunitensi guardano soprattutto quei due numeri. Il tuo punteggio dipende da quante domande indovini, quindi non c'è nessun motivo per lasciarne una in bianco.

Tutto il resto della giornata cambia. Le tariffe, quante volte puoi ripetere l'esame, l'attesa tra un tentativo e l'altro, cosa puoi portare in aula e quali strumenti a schermo ti vengono dati durante la sezione quantitativa li fissa l'ADA e vengono rivisti. Leggi la guida per i candidati DAT aggiornata su ada.org invece di fidarti di un vecchio manuale di preparazione, o di questa pagina.

Come usare questo assaggio

Il DAT vero conta 280 domande su quattro sezioni. Quindici non possono sostituirlo, e questo assaggio non ci prova. Quello che può fare è mostrarti quale delle quattro aree è la più fragile prima che tu costruisca un piano di studio attorno a quella sbagliata. Il mix qui è di sei domande di scienze naturali, due sul ragionamento percettivo, tre brani di lettura e quattro domande quantitative.

Le domande percettive hanno bisogno di un avvertimento. Il Perceptual Ability Test vero è del tutto visivo: fori e aperture, riconoscimento delle viste dall'alto, di fronte e di lato, ordinamento degli angoli, perforazione della carta, conteggio dei cubi e piegatura di modelli. Una pagina di testo non può disegnare quelle cose, e fingere un'immagine a parole insegnerebbe abitudini sbagliate. Quindi i due quesiti percettivi qui verificano invece le regole e il ragionamento dietro due di quei compiti. Allenati sulla sezione vera con diagrammi veri, perché la velocità nel PAT nasce da un riconoscimento di schemi che si costruisce solo guardando.

Fallo tutto d'un fiato senza appunti, poi leggi ogni spiegazione, comprese quelle delle domande a cui hai risposto giusto. Considera una risposta sbagliata un argomento e non un dettaglio. Tutto quello che c'è qui è stato scritto dal team di StudyPDF partendo dallo schema di contenuto DAT pubblicato. Non sono domande dell'ADA, StudyPDF non è affiliata all'American Dental Association, e niente in questa pagina è un consiglio odontoiatrico o medico. È esercitazione per l'esame.

Come StudyPDF crea test completi dal tuo materiale

Quindici domande possono indicarti un'area debole. Non bastano a prepararti per un esame da 280 domande, e una banca dati generica raramente corrisponde alla chimica organica su cui ha davvero insistito il tuo professore o alla biologia a cui il tuo libro DAT dedica quaranta pagine.

StudyPDF parte invece dal tuo materiale. Carica il tuo manuale di preparazione DAT, gli appunti di chimica generale, i tuoi schemi delle reazioni organiche o le slide delle lezioni del tuo corso di biologia, e Bo, l'agente di studio, crea test completi da quelle pagine esatte. Ogni domanda nasce da ciò che hai caricato e ogni spiegazione rimanda al punto da cui viene la risposta, così puoi andare subito alla fonte quando qualcosa non ti torna. Genera un test nuovo quando vuoi, restringilo a un'area sola come la stereochimica o gli equilibri acido base, e tieni traccia dei concetti che continui a sbagliare.

Per iniziare non serve un file. Se non hai niente da caricare, nomina invece un argomento, per esempio il metabolismo dei carboidrati o i meccanismi di reazione, e Bo ci scrive sopra un test. Inizi gratis.