OAT — Optometry Admission Test practice questions and exam guide

Which describes a Markovnikov addition (e.g., HX addition to alkene)?

1. H adds to more substituted carbon
2. H adds to the less substituted carbon (carbon with more H's); the X adds to the more substituted carbon — forms more stable carbocation intermediate
3. Random orientation
4. Always anti-Markovnikov
5. Both carbons identical

Answer: B — H adds to the less substituted carbon (carbon with more H's); the X adds to the more substituted carbon — forms more stable carbocation intermediate

Markovnikov's rule: 'rich get richer.' In HX + alkene, H to less-substituted C (more H atoms), X to more-substituted C. Intermediate carbocation is more stable on more-substituted C. Anti-Markovnikov: peroxides, radical mechanism. Org chem core.

OAT Physics: A converging lens forms a real image when:

1. Object PLACED BEYOND focal point (do > f); image is real, inverted, formed on opposite side of lens; if object inside f, image is virtual, upright, magnified
2. Object closer than focal length
3. Always
4. Never
5. With concave only

Answer: A — Object PLACED BEYOND focal point (do > f); image is real, inverted, formed on opposite side of lens; if object inside f, image is virtual, upright, magnified

Thin lens equation: 1/f = 1/d_o + 1/d_i. Image properties depend on position. Critical for OAT (optometry-focused: optics central!). Converging (convex) vs diverging (concave) lens behaviors. Real images can be projected on screen; virtual cannot.

Which describes the EYE's lens accommodation?

1. Lens never changes shape
2. Ciliary muscles contract/relax to change lens curvature — focusing on near (rounder) or far objects (flatter) — a topic particularly relevant to optometry
3. Pupil constriction
4. Cornea changes shape
5. Retina moves

Answer: B — Ciliary muscles contract/relax to change lens curvature — focusing on near (rounder) or far objects (flatter) — a topic particularly relevant to optometry

Accommodation: ciliary muscles adjust lens curvature for focusing. Near vision: muscles contract, lens rounds (greater refractive power). Far vision: muscles relax, lens flattens. Presbyopia: age-related loss of accommodation. OAT relevance: optometry-specific bio.

An object 30 cm from a concave (converging) lens with focal length 10 cm produces an image with magnification:

1. Real, inverted, magnification |m| = 0.5 (size reduced)
2. Virtual, upright, |m| = 2.0
3. No image
4. Real, upright
5. Always same size

Answer: A — Real, inverted, magnification |m| = 0.5 (size reduced)

Thin lens equation: 1/f = 1/do + 1/di. 1/10 = 1/30 + 1/di. di = 15 cm (positive: real image). Magnification m = -di/do = -15/30 = -0.5. Negative sign: inverted. |m| = 0.5: reduced. Optics important on OAT (optometry-relevant).

The OAT (Optometry Admission Test) is administered by:

1. The Association of Schools and Colleges of Optometry / ADA — required for admission to most US optometry schools
2. ETS
3. The Princeton Review
4. The College Board

Answer: A — The Association of Schools and Colleges of Optometry / ADA — required for admission to most US optometry schools

A) Official administrator. B/C/D) Each is incorrect.

OAT Physics: Snell's Law for refraction:

1. Not used
2. v = fλ
3. Just for water
4. F = ma
5. n₁ sin θ₁ = n₂ sin θ₂ — light bends TOWARD normal entering denser medium (higher n) and away from normal exiting; critical angle: total internal reflection if θ > critical

Answer: E — n₁ sin θ₁ = n₂ sin θ₂ — light bends TOWARD normal entering denser medium (higher n) and away from normal exiting; critical angle: total internal reflection if θ > critical

Snell's Law: refraction across boundaries. Refractive index n: vacuum (1), water (1.33), glass (~1.5), diamond (2.4). Total internal reflection at θc = arcsin(n₂/n₁) when going dense → less dense (fiber optics, mirages). Vision: refractive error correction.

Snell's law describes:

1. Refraction — light bending at boundary between media of different refractive indices: n₁ sin θ₁ = n₂ sin θ₂
2. Reflection only
3. Polarization
4. Diffraction only
5. Absorption

Answer: A — Refraction — light bending at boundary between media of different refractive indices: n₁ sin θ₁ = n₂ sin θ₂

Snell's law: n₁ sin θ₁ = n₂ sin θ₂. Light entering denser medium (higher n) bends toward normal. Total internal reflection when going from dense → less dense at critical angle. Foundation of optics. Highly relevant to optometry (lenses, fiber optics).

OAT Gen Chem: Standard ENTHALPY of formation:

1. Always zero
2. Always positive
3. Heat change when 1 mol of compound is formed from elements in their STANDARD STATES; ΔHf° = 0 for elements in standard state (e.g., O₂(g), H₂(g), C(graphite))
4. Random
5. Just for gases

Answer: C — Heat change when 1 mol of compound is formed from elements in their STANDARD STATES; ΔHf° = 0 for elements in standard state (e.g., O₂(g), H₂(g), C(graphite))

ΔHf°: tabulated thermochemical data. Allows calculating ΔHrxn = Σ ΔHf°(products) - Σ ΔHf°(reactants). Most ΔHf negative (exothermic formation = stable compound). Diamond's ΔHf relative to graphite +1.9 kJ/mol — graphite is more stable. OAT Gen Chem.

The OAT's Physics section covers:

1. Calculus and differential equations only
2. No physics topics
3. Topics from a first-year college physics course — mechanics, electricity and magnetism, optics, waves, thermodynamics, and modern physics fundamentals — 40 questions over 50 minutes
4. Only nuclear physics

Answer: C — Topics from a first-year college physics course — mechanics, electricity and magnetism, optics, waves, thermodynamics, and modern physics fundamentals — 40 questions over 50 minutes

C) Standard coverage. A/B/D) Each is incorrect.

Mendelian genetics: a cross between Bb (heterozygous) × bb (homozygous recessive) yields what genotype ratio?

1. 1 BB : 2 Bb : 1 bb
2. 3:1 dominant:recessive
3. All BB
4. All bb
5. 1 Bb : 1 bb (50% heterozygous, 50% homozygous recessive)

Answer: E — 1 Bb : 1 bb (50% heterozygous, 50% homozygous recessive)

Bb × bb Punnett square: 50% Bb, 50% bb. Phenotype ratio 1:1 (if complete dominance). Test cross: distinguishes homozygous dominant from heterozygous. Compare Bb × Bb: 1:2:1 genotype, 3:1 phenotype.

OAT Biology: NEPHRON of kidney:

1. Functional unit of kidney; filtration in glomerulus → reabsorption in proximal tubule + Loop of Henle + distal tubule → secretion → collecting duct; ~1M nephrons per kidney; regulates blood pressure, pH, water balance
2. Just a tube
3. Brain region
4. Heart valve
5. Lung alveolus

Answer: A — Functional unit of kidney; filtration in glomerulus → reabsorption in proximal tubule + Loop of Henle + distal tubule → secretion → collecting duct; ~1M nephrons per kidney; regulates blood pressure, pH, water balance

Nephron parts: Bowman's capsule (filtration), proximal convoluted tubule (most reabsorption), Loop of Henle (concentration gradient), distal convoluted tubule (regulated), collecting duct. ADH (vasopressin): water reabsorption. Aldosterone: Na⁺ reabsorption. OAT bio physiology.

A capacitor stores energy in:

1. The electric field between plates — energy U = ½CV² = ½QV = ½Q²/C
2. Mechanical motion
3. Magnetic field
4. Gravitational field
5. Heat

Answer: A — The electric field between plates — energy U = ½CV² = ½QV = ½Q²/C

Capacitor energy stored in electric field. U = ½CV² (or equivalent forms). Capacitance C = εA/d. In contrast: inductors store energy in magnetic field (U = ½LI²). Both fundamental energy storage elements in circuits.

Insulin vs glucagon?

Insulin: lowers blood sugar (uptake by cells). Glucagon: raises blood sugar.

Why does eye need cornea + lens (two parts)?

Cornea provides most refraction. Lens fine-tunes for distance.

Electromagnetic spectrum order (low → high freq)?

Radio → micro → IR → visible → UV → X-ray → gamma.

Wave equation?

v = fλ. Speed = frequency × wavelength.

Le Chatelier's principle?

System shifts to oppose change in equilibrium.

OAT RC strategy?

Skim first. Use 'search and destroy' for specific answers.