Lebanese University Faculty of Public Health Entrance Exam flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Cell theory

All living organisms are made of one or more cells, the cell is the basic unit of life, and all cells arise from pre-existing cells.

Prokaryotic vs eukaryotic cells

Prokaryotes lack a membrane-bound nucleus and organelles and have 70S ribosomes; eukaryotes have a nucleus, membrane-bound organelles, and 80S cytoplasmic ribosomes.

DNA replication

The semiconservative process in which each parental DNA strand serves as a template for a new complementary strand, producing two identical DNA molecules.

Mendelian dihybrid ratio

For two independently assorting unlinked genes, the F2 phenotypic ratio from a cross of double heterozygotes is 9:3:3:1.

Hardy–Weinberg equilibrium

Allele and genotype frequencies remain constant across generations when there is no mutation, migration, selection, or genetic drift and mating is random; p² + 2pq + q² = 1.

Mole concept

One mole contains 6.022×10²³ particles; the number of moles equals mass divided by molar mass (n = m/M).

Molarity

Molarity (M) is the number of moles of solute per liter of solution: M = n/V, where V is in liters.

pH scale

pH = −log[H⁺]; values below 7 are acidic, 7 is neutral, and above 7 is basic at 25 °C, where pH + pOH = 14.

Le Chatelier's principle

When a system at equilibrium is disturbed by a change in concentration, pressure, or temperature, it shifts to counteract the disturbance and restore equilibrium.

Oxidation and reduction

Oxidation is loss of electrons and an increase in oxidation number; reduction is gain of electrons and a decrease in oxidation number.

Ideal gas law

PV = nRT, where P is pressure, V is volume, n is moles, R is the gas constant (0.08206 L·atm·mol⁻¹·K⁻¹), and T is absolute temperature in kelvin.

Newton's second law

The net force on an object equals its mass times its acceleration: ΣF = ma, with force in newtons, mass in kilograms, and acceleration in m/s².

Kinetic energy

The energy of motion, calculated as KE = ½mv², where m is mass in kilograms and v is speed in meters per second; the unit is the joule.

Ohm's law

For an ohmic conductor, voltage equals current times resistance: V = IR, with V in volts, I in amperes, and R in ohms.

Wave equation

Wave speed equals frequency times wavelength: v = fλ, where v is in m/s, f in hertz, and λ in meters.

Snell's law

At an interface, n₁ sinθ₁ = n₂ sinθ₂ relates the refractive indices and angles of incidence and refraction; n = c/v.

Half-life

The time required for half of a radioactive sample to decay; after n half-lives, the remaining fraction is (1/2)ⁿ.

Quadratic formula

For ax² + bx + c = 0 with a ≠ 0, the solutions are x = [−b ± √(b² − 4ac)] / (2a); the discriminant b² − 4ac determines the number of real roots.

Logarithm product rule

The logarithm of a product equals the sum of the logarithms: log(ab) = log a + log b; similarly log(a/b) = log a − log b.

Chain rule

For a composite function f(g(x)), the derivative is f′(g(x))·g′(x); it is used to differentiate nested functions.

Sample variance

The average squared deviation from the mean, computed as s² = Σ(xᵢ − x̄)²/(n − 1); the standard deviation is its square root.

Law of cosines

In any triangle, c² = a² + b² − 2ab cos C, where C is the angle opposite side c; it generalizes the Pythagorean theorem.

WHO definition of health

Health is a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity, as stated in the 1948 WHO Constitution.

Levels of prevention

Primary prevention prevents disease onset (vaccination); secondary prevention detects disease early (screening); tertiary prevention limits disability and promotes rehabilitation.

Incidence versus prevalence

Incidence is the number of new cases in a population over a period; prevalence is the total number of existing cases at a given time.

Infant mortality rate

The number of deaths of children under age one per 1,000 live births in a given year, a key indicator of population health.

Herd immunity threshold

The proportion of a population that must be immune to interrupt transmission, approximated by 1 − 1/R₀; for measles this is roughly 92–95%.

Epidemiologic triad

A model of disease causation involving the interaction of an agent, a susceptible host, and the environment.

Sensitivity and specificity

Sensitivity is the proportion of true cases correctly identified as positive; specificity is the proportion of non-cases correctly identified as negative.

Correlation versus causation

An association between two variables does not prove that one causes the other; confounding, reverse causation, and chance can explain correlations.

Controlled experiment

A study in which a treatment group is compared with a control group that differs only in the variable under investigation, with other factors held constant.

Active versus passive voice

In active voice the subject performs the action (The nurse gave the vaccine); in passive voice the subject receives the action (The vaccine was given).