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Alle 15 spørgsmål i overblik

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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
   Vis svar og forklaring

   Svar: 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?

   Vælg alle, der passer.

   • 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
   Vis svar og forklaring

   Svar: 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
   Vis svar og forklaring

   Svar: 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.

   Muligheder for felt 1: 11.2, 22.4, 44.8, 62.4

   Vis svar og forklaring

   Svar: 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
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   Svar: 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.

   Muligheder for felt 1: 3, 6, 8, 9

   Muligheder for felt 2: 0, 1, 2, 3

   Vis svar og forklaring

   Svar: 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
   Vis svar og forklaring

   Svar: 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?

   Vælg alle, der passer.

   • 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
   Vis svar og forklaring

   Svar: 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
   Vis svar og forklaring

   Svar: 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?

    Vælg alle, der passer.

    • 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
    Vis svar og forklaring

    Svar: 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
    Vis svar og forklaring

    Svar: 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
    Vis svar og forklaring

    Svar: 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
    Vis svar og forklaring

    Svar: 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.

    Muligheder for felt 1: 6, 15, 24, 40

    Vis svar og forklaring

    Svar: 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
    Vis svar og forklaring

    Svar: 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.

Hvad DAT faktisk spørger dig om

Dental Admission Test er en computerbaseret eksamen, der ejes af American Dental Association og tages på et testcenter. Den har fire dele. Survey of the Natural Sciences giver dig 100 spørgsmål på 90 minutter, fordelt på 40 i biologi, 30 i almen kemi og 30 i organisk kemi. Perceptual Ability Test giver dig 90 spørgsmål på 60 minutter. Reading Comprehension giver dig 50 spørgsmål på 60 minutter. Quantitative Reasoning giver dig 40 spørgsmål på 45 minutter. Med den valgfri pause og den valgfri spørgeskemaundersøgelse efter prøven varer aftalen lidt over fem timer.

Scorer rapporteres som skalascorer fra 1 til 30, og ADA beskriver 19 som cirka gennemsnitlig præstation på landsplan. Du får en separat score for biologi, almen kemi, organisk kemi, læseforståelse, kvantitativ ræsonnering og Perceptual Ability Test. Academic Average er det afrundede gennemsnit af de fem faglige scorer, og den perceptuelle score er med vilje holdt udenfor, så PAT læses for sig. Det er derfor, tandlægestudierne har en tendens til at se hårdest på netop de to tal. Din score afhænger af, hvor mange spørgsmål du svarer rigtigt på, så der er ingen grund til at lade et stå tomt.

Alt andet ved dagen flytter sig. Gebyrer, hvor ofte du må gå op igen, ventetiden mellem forsøg, hvad du må tage med ind i lokalet, og hvilke værktøjer du får på skærmen under den kvantitative del, fastsættes alt sammen af ADA og bliver revideret. Læs den aktuelle DAT-kandidatvejledning på ada.org frem for at stole på en gammel repetitionsbog, eller på denne side.

Sådan bruger du smagsprøven

Den rigtige DAT kører 280 spørgsmål fordelt på fire dele. Femten kan ikke stå i stedet for det, og den her smagsprøve forsøger heller ikke. Det, den kan, er at vise dig, hvilket af de fire områder der er mest usikkert, før du bygger en læseplan op om det forkerte. Blandingen her er seks naturvidenskabelige spørgsmål, to om perceptuel ræsonnering, tre læsetekster og fire kvantitative spørgsmål.

De perceptuelle spørgsmål kræver en advarsel. Den rigtige Perceptual Ability Test er udelukkende visuel: nøglehuller og åbninger, genkendelse af top-, front- og endeview, rangordning af vinkler, hulning, terningtælling og mønsterfoldning. En tekstside kan ikke tegne det, og at forfalske et billede med ord ville lære dig de forkerte vaner. Derfor tester de to perceptuelle spørgsmål her reglerne og ræsonnementet bag to af de opgaver i stedet. Træn selve delen med rigtige tegninger, for farten på PAT kommer af mønstergenkendelse, du kun kan opbygge ved at kigge.

Tag den i ét stræk uden noter, og læs så hver eneste forklaring, også dem du svarede rigtigt på. Behandl et forkert svar som et emne frem for som et faktum. Alt her er skrevet af StudyPDF-teamet ud fra den offentliggjorte DAT-indholdsoversigt. Det er ikke ADA-spørgsmål, StudyPDF er ikke tilknyttet American Dental Association, og intet på denne side er tandlægefaglig eller medicinsk rådgivning. Det er eksamenstræning.

Sådan bygger StudyPDF fulde øveprøver ud fra dit materiale

Femten spørgsmål kan pege dig mod et svagt område. De kan ikke gøre dig klar til en eksamen med 280 spørgsmål, og en generisk spørgsmålsbank rammer sjældent den organiske kemi, din underviser faktisk lagde vægt på, eller den biologi, din DAT-bog bruger fyrre sider på.

StudyPDF arbejder ud fra dit materiale i stedet. Upload din DAT-repetitionsbog, dine noter fra almen kemi, dine oversigter over organiske reaktioner eller forelæsningsslidesene fra dit biologiforløb, og Bo, studieagenten, bygger fuldlange øveprøver ud fra præcis de sider. Hvert spørgsmål bygger på det, du har uploadet, og hver forklaring peger tilbage på, hvor svaret kom fra, så du kan gå direkte til kilden, når noget ser forkert ud. Lav en ny prøve når du vil, hold den på ét område som stereokemi eller syre-base-ligevægte, og følg med i hvilke begreber du bliver ved med at misse.

Du behøver ikke en fil for at komme i gang. Har du ikke noget at uploade, så nævn et emne i stedet, for eksempel kulhydratstofskifte eller reaktionsmekanismer, så skriver Bo en øveprøve ud fra det. Gratis at komme i gang.