OAT Cheat Sheet 2026

The 30 highest-yield OAT facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. What is the primary role of the corpus luteum after ovulation? → Secrete progesterone to maintain the uterine lining
2. The process by which a cell engulfs large solid particles is called: → Phagocytosis
3. Which of the following best describes the Claisen rearrangement? → Concerted [3,3]-sigmatropic rearrangement of an allyl vinyl ether
4. What is the sum of the interior angles of a hexagon? → 720°
5. Which reagent selectively reduces an ester to a primary alcohol without reducing isolated alkene groups? → LiAlH4
6. What is the de Broglie wavelength of a particle? → Inversely proportional to its momentum
7. Which thermodynamic process occurs at constant pressure? → Isobaric
8. Which of the assertions regarding trypsin is untrue? → It is operative over a wide pH range
9. In Young's double-slit experiment, if the slit separation is doubled while keeping all else constant, the fringe spacing: → Is halved
10. Which of the following correctly ranks the given types of electromagnetic radiation from longest wavelength to shortest wavelength? → Radio waves, Infrared, Visible light, X-rays
11. Which organelle is the primary site of fatty acid beta-oxidation in animal cells? → Mitochondrial matrix
12. What is the stereochemical result of bromine addition to (E)-2-butene? → Meso-2,3-dibromobutane
13. A train travels 240 miles in 3 hours, then 180 miles in 2 hours. What is the average speed for the entire trip? → 84 mph
14. During the Calvin cycle, CO₂ is first incorporated into a stable organic molecule by combining with: → Ribulose-1,5-bisphosphate (RuBP)
15. During meiosis II, what separates to produce haploid daughter cells? → Sister chromatids
16. Which small non-coding RNA class guides Argonaute proteins to silence target mRNAs post-transcriptionally? → miRNA
17. Which of the following best describes an exergonic reaction? → Releases net free energy and is thermodynamically spontaneous
18. In the process of eutrophication, what is the direct cause of the depletion of dissolved oxygen in the water, leading to the creation of a 'dead zone'? → The decomposition of dead algae by aerobic bacteria.
19. The speed of light in a vacuum is approximately: → 3 × 10⁸ m/s
20. An amide bond is best described as having which character due to resonance? → Partial double bond character (restricted rotation)
21. Which cell junction allows direct cytoplasmic communication between adjacent animal cells? → Gap junctions
22. Which carbonyl compound is most reactive toward nucleophilic addition? → Acyl chloride
23. The reaction of (2E,4E)-hexa-2,4-diene with maleic anhydride is a classic example of which type of reaction? → Diels-Alder Cycloaddition
24. What is the solution to the system: x + y = 10 and x − y = 4? → x=7, y=3
25. Which organelle is primarily responsible for modifying and sorting proteins destined for secretion? → Golgi apparatus
26. A student observes that a bacterial colony grows on a plate containing ampicillin. This resistance is most likely due to: → Acquired mutation providing selective advantage
27. In a dihybrid cross between two AaBb individuals, what fraction of offspring are expected to be aabb? → 1/16
28. The ratio of boys to girls in a class is 3:5. If there are 24 boys, how many girls are there? → 40
29. Which phenomenon explains why the sky appears blue? → Rayleigh scattering of shorter wavelengths
30. Which color of visible light has the greatest energy per photon? → Violet