Anyone hoping to attend dental school in the United States much first achieve a high score on the Dental Admission Test, or DAT. This is the official admission exam used by all dental schools in the US. According to the American Dental Association, which conducts the test, anyone interested in taking the exam should have completed at least one year of college with courses in organic chemistry, general chemistry, and biology. The typical applicant has completed at least two years of college before taking the exam. It can be taken year-round at Prometric testing centers, which are located all over the US and its territories.
There are four sections on the DAT, all of them multiple choice. They are: Natural Sciences, Perceptual Ability (commonly referred to as PAT), Reading Comprehension, and Quantitative Reasoning. It takes five hours to complete the exam. (Applicants may take an optional 15 minute break during the test if they so choose.)
Natural Sciences contains 40 biology questions, 30 general chemistry questions, and 30 organic chemistry questions, for a total of 100, with a time limit of 90 minutes. On the PAT, there are 90 questions evenly divided between six different perception categories – keyhole, top/front/end visualization, angle ranking, hold punches, cube counting, and pattern folding. The PAT time limit is 60 minutes. In the Reading Comprehension section, applicants will have 60 minutes to answer 50 questions about three reading passages. In the Quantitative Reading section there are 40 questions covering basic math, fractions, roots, algebra, and trigonometry. Ten of these questions are in the form of word problems.
Scores on the DAT are scaled from 1-30, with 17 being average. However, there is no “passing” score per se, as each dental schools sets its own admission standards. While it’s true that schools try to “look at the whole person” and not just their GPA and test scores, the DAT score is still extremely important, probably outweighing any other factor on a person’s application. Those who are serious about becoming dentists should spend a lot of time and study prepping for the exam, as embarking on their hoped for career likely hinges upon the score they achieve.
1. Which of the following organelles are involved in the generation of metabolic energy in the form of ATP?
D. the endoplasmic reticulum
2. Which of the following statements about the process of DNA replication is NOT true?
A. The double-stranded DNA molecule is unwound by an enzyme that duplicates both strands at the same time.
B. The replication enzymes are capable of proofreading the copy they make.
C. Mutations can occur if the replication enzyme skips reading one of the bases.
D. The duplicated double helices each contain one old strand and one newly synthesized DNA strand.
3. The reason penicillin and related antibiotics are not toxic to humans is
A. mammals, but not bacteria, have enzymes called beta-lactamases, which can destroy these compounds.
B. they cannot cross the cytoplasmic membrane of eukaryotic cells.
C. penicillin inhibits protein synthesis on bacterial ribosomes but does not affect eukaryotic ribosomes.
D. animal cells do not have a cell wall, which is the target for penicillin in bacterial cells.
4. A compound with the molecular formula C6H14O is
A. an alcohol or an ether
B. an aldehyde or a ketone
C. an alcohol or an aldehyde
D. an ether or a ketone
5. The NMR spectrum of a compound shows a triplet near **1.0 and a related quartet near **1.3 with the integration ratio of 3:2. This indicates
A. an isopropyl group is present in the molecule
B. an ethyl group is present in the molecule
C. the compound is an ethyl ester
D. one or more identical ethyl groups are present in the molecule
6. The Grignard reaction between isobutyl magnesium bromide and cyclohexanone in anhydrous diethyl ether produces
B. cyclohexyl 2-methylpropyl ether
D. cyclohexyl 2-methylpropanoate
For question 7:
A three-dimensional object is shown, followed by outlines of five apertures or openings.
First, you are to imagine how the object looks from all directions (rather than from a single direction as shown). Then, pick from the five apertures outlined, the opening through which the object could pass directly if the proper side were inserted first.
Here are the rules:
Prior to passing through the aperture, the irregular solid object may be turned in any direction. It may be started through the aperture on a side not shown.
Once the object has started through the aperture, it may not be twisted or turned. It must pass completely through the opening. The opening is always the exact shape of the appropriate external outline of the object.
Both the object and apertures are drawn to the same scale. Thus, it is possible for an opening to be the correct shape but too small for the object. In all cases, however, differences are large enough to judge by eye.
There are no irregularities in any hidden portion of the object. However, if the figure has symmetric indentations, the hidden portion is symmetric with the part shown.
There is only one correct aperture.
For question 8:
A flat square of paper is folded one or more times. The broken lines indicate the original position of the paper. The solid lines indicate the position of the folded paper. The paper is never turned or twisted. The folded paper always remains within the edges of the original square.
There are multiple folds in each item. After the last fold a hole is punched in the paper. Your task is to mentally unfold the paper and determine the position of the holes on the original square. Choose the pattern of black circles that indicates the position of the holes on the original square. There is only one correct pattern.
In questions 9 a flat pattern is presented. This pattern is to be folded into a three dimensional figure. The correct figure is one of the four given at the right of the pattern. There is only one correct figure. The outside of the pattern is what is seen at the left.
10. Given the equation y=2 x2-8 x+5 , find the x-coordinate of the minimum value.
11. A rectangular prism has a height of 2 inches and a square base with side 16 inches. Find the length of the edge of a cube with the same volume.
Answers & Explanations
1. C: Electron transport, which occurs in the mitochondria, is a process in which the metabolic energy derived from the oxidation of glucose or other sugars is captured in ATP molecules. In contrast, the chloroplast is the organelle where photosynthesis, which uses light as a source of energy and a related set of energy transport molecules, leads to the synthesis of sugars using carbon dioxide as a carbon source. Neither the nucleus nor the endoplasmic reticulum is involved in the generation of metabolic energy. Rather, they are the sites where ATP and other high-energy compounds are utilized in the synthesis of DNA/RNA and proteins, respectively.
2. A: The structure of the double helical DNA molecule is termed “anti-parallel” to indicate that the bonding process between the sugars and phosphates, which make up the backbone of the DNA molecule, runs in opposite directions on the two strands. Since this would require a DNA synthetic enzyme, called a DNA polymerase, to add nucleotide monomers in two directions at the same time, it is impossible for one enzyme to replicate both strands. Most DNA polymerases can backspace and remove an incorrectly inserted nucleotide in a process known as proofreading. Sometimes mistakes are not corrected. In those cases where an extra nucleotide is inserted or a base is not copied, a mutation-termed a frameshift mutation-will result. The process of DNA replication is termed semi-conservative, indicating that each strand of the double helix is used as a template for a new copy of the other, complementary, DNA sequence.
3. D: The effectiveness of penicillin is a result of the fact that it looks to many bacteria like a component of their cell walls. The biochemical machinery that assembles the cell wall is inhibited by penicillin and related antibiotics (beta-lactams and cephalosporins). When treated with these agents, bacteria can’t construct a cell wall. The absence of a cell wall makes bacteria fragile and susceptible to lysis when exposed to solutions where the salt concentration is lower outside the cell than inside (hypotonic solutions). Animal cells, which lack a cell wall, and even plant cells, which have an entirely different cell wall structure, are unharmed by these antibiotics.
4. A: The number of carbon and hydrogen atoms corresponds to the general formula for alkanes, CnH2n+2. This indicates that the compound is saturated and there are no double bonds to any carbon atoms. There can therefore only be single bonds involving the C and O atoms, which is satisfied only if the compound is an alcohol (one of thirteen possible isomers) or an ether (thirteen other possible isomers). Aldehydes and ketones have a double bond between a carbon atom and an oxygen atom and therefore cannot have a formula that agrees with the formula C6H14O.
5. D: Proton signals in NMR exhibit “spin splitting” according to the number of different protons on adjacent carbon atoms. Protons experiencing identical magnetic environments produce identical signals, so the three protons of a single methyl group produce just one peak at about 1.0. In an ethyl group, -CH2CH3, the three methyl protons are affected by the two -CH2- protons and their signal is split into three slightly different peaks called a “triplet”. The -CH2- proton signal is split by the three -CH3-protons into four slightly different peaks called a quartet. Integration of the quartet and the triplet sets of peaks is in the ratio of 2:3 respectively, according to the number of each different type of proton. There is certainly one ethyl group present indicated by this pattern, but it does not preclude the possibility that there may be two or more identical ethyl groups in the molecule. They would still have a 2:3 integration ratio, so in this case the correct answer is d).
10. B: This equation is a parabola that opens up, so there is only one extreme point, which is a minimum. To find the x-coordinate of the minimum, first find the first derivative of the given equation.
y =2x2-8x + 5⇒y‘=4x-8
Once you have found the first derivative, set it equal to zero and solve for x. This is the x-coordinate of the minimun point. 4x – 8 = 0 4x⇒8⇒x = 2
Alternately, try plotting points to see which gives the lowest value for y when substituted in the original equation. The four choices given are -2, 2, 3, and 7. When -2 is substituted in the original problem, you get 2(-2)2-8(-2)+5=29.
When 2 is substituted in the original problem, you get 2(2)2-8(2)+5=-3
When 3 is substituted in the original problem, you get 2(3)2-8(3)+5=-1
When 7 is substituted in the original problem, you get 2(7)2-8(7)+5=47
The smallest value for y occurred when x = 2.
11. B: Start by finding the volume of the rectangular prism. The formula for the volume of any prism is the area of the base times the height. In this case the base is a square with side 16, so the area of the base is 16×16=256. The height is 2, so the volume of the rectangular prism is 256×2=512. The formula for the volume of a cube is also the area of the base times its height. In the case of a cube, all the edges are the same, so the formula can be written V, and the length of an edge is 3√V=3√512 =3√8x8x8 =8.