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Liever eerst lezen? Hieronder staat elke vraag uit deze oefentoets. Antwoorden en uitleg blijven ingeklapt tot je ze opent.

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
   Toon antwoord en uitleg

   Antwoord: 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?

   Selecteer alles wat van toepassing is.

   • 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
   Toon antwoord en uitleg

   Antwoord: 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
   Toon antwoord en uitleg

   Antwoord: 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.

   Opties voor invulveld 1: 11.2, 22.4, 44.8, 62.4

   Toon antwoord en uitleg

   Antwoord: 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
   Toon antwoord en uitleg

   Antwoord: 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.

   Opties voor invulveld 1: 3, 6, 8, 9

   Opties voor invulveld 2: 0, 1, 2, 3

   Toon antwoord en uitleg

   Antwoord: 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
   Toon antwoord en uitleg

   Antwoord: 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?

   Selecteer alles wat van toepassing is.

   • 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
   Toon antwoord en uitleg

   Antwoord: 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
   Toon antwoord en uitleg

   Antwoord: 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?

    Selecteer alles wat van toepassing is.

    • 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
    Toon antwoord en uitleg

    Antwoord: 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
    Toon antwoord en uitleg

    Antwoord: 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
    Toon antwoord en uitleg

    Antwoord: 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
    Toon antwoord en uitleg

    Antwoord: 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.

    Opties voor invulveld 1: 6, 15, 24, 40

    Toon antwoord en uitleg

    Antwoord: 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
    Toon antwoord en uitleg

    Antwoord: 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.

Wat de DAT echt van je vraagt

De Dental Admission Test is een computerexamen van de American Dental Association dat je in een testcentrum maakt. Hij bestaat uit vier delen. De Survey of the Natural Sciences geeft je 100 vragen in 90 minuten, verdeeld over 40 biologie, 30 algemene scheikunde en 30 organische scheikunde. De Perceptual Ability Test geeft je 90 vragen in 60 minuten. Reading Comprehension geeft je 50 vragen in 60 minuten. Quantitative Reasoning geeft je 40 vragen in 45 minuten. Met de optionele pauze en de optionele enquête na afloop duurt de afspraak iets meer dan vijf uur.

Scores worden gerapporteerd als schaalscores van 1 tot 30, en de ADA omschrijft een 19 als ruwweg een gemiddelde prestatie op landelijk niveau. Je krijgt een aparte score voor biologie, algemene scheikunde, organische scheikunde, begrijpend lezen, kwantitatief redeneren en de Perceptual Ability Test. Het Academic Average is het afgeronde gemiddelde van de vijf academische scores, en de perceptuele score blijft er met opzet buiten, zodat de PAT op zichzelf wordt gelezen. Daarom kijken tandheelkundeopleidingen het hardst naar die twee getallen. Je score hangt af van hoeveel vragen je goed hebt, dus er is geen reden om er een leeg te laten.

Al het andere rond de examendag beweegt. De kosten, hoe vaak je opnieuw mag, de wachttijd tussen pogingen, wat je de zaal in mag nemen en welke hulpmiddelen je op het scherm krijgt tijdens het kwantitatieve onderdeel worden allemaal door de ADA vastgesteld en worden herzien. Lees de actuele DAT candidate guide op ada.org in plaats van te vertrouwen op een oud voorbereidingsboek, of op deze pagina.

Hoe je deze oefentoets gebruikt

De echte DAT telt 280 vragen over vier onderdelen. Vijftien kunnen daar niet voor doorgaan, en dat probeert deze oefentoets ook niet. Wat hij wel kan, is laten zien welk van de vier gebieden het wankelst is, voordat je een studieplan om het verkeerde gebied heen bouwt. De mix hier is zes vragen natuurwetenschappen, twee over ruimtelijk redeneren, drie leesteksten en vier rekenvragen.

Bij de perceptuele vragen hoort een waarschuwing. De echte Perceptual Ability Test is volledig visueel: sleutelgaten en openingen, het herkennen van boven-, voor- en zijaanzicht, hoeken rangschikken, gaten knippen, kubussen tellen en patronen vouwen. Een tekstpagina kan die niet tekenen, en een plaatje in woorden namaken zou je de verkeerde gewoontes aanleren. Daarom toetsen de twee perceptuele vragen hier de regels en de redenering achter twee van die taken. Oefen het onderdeel zelf met echte tekeningen, want snelheid op de PAT komt uit patroonherkenning die je alleen opbouwt door te kijken.

Maak hem in een keer zonder aantekeningen, en lees daarna elke uitleg, ook die bij vragen die je goed had. Behandel een fout antwoord als een onderwerp en niet als een feit. Alles hier is geschreven door het StudyPDF-team op basis van de openbaar gepubliceerde stofomschrijving van de DAT. Het zijn geen vragen van de ADA, StudyPDF heeft geen band met de American Dental Association, en niets op deze pagina is tandheelkundig of medisch advies. Het is examenoefening.

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