Galicia PAU General Sciences flashcards

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

Prokaryotic vs eukaryotic ribosomes

Prokaryotes carry 70S ribosomes made of 50S and 30S subunits, while eukaryotic cytoplasmic ribosomes are 80S made of 60S and 40S subunits. This difference is the basis of many antibiotic targets.

ATP yield of aerobic respiration

Complete oxidation of one glucose molecule yields about 30 to 32 ATP: 2 from glycolysis, 2 from the Krebs cycle, and roughly 26 to 28 from oxidative phosphorylation using the NADH and FADH2 produced.

Dihybrid selfing ratio

Crossing two heterozygotes for two independently assorting genes (AaBb x AaBb) gives a 9:3:3:1 phenotypic ratio. Deviations suggest linkage, epistasis or lethal genotypes.

Sex-linked recessive inheritance

A recessive allele on the X chromosome affects males far more often because they have only one X. A carrier mother and unaffected father produce 50% affected sons and 50% carrier daughters.

Semiconservative DNA replication

Helicase unwinds the double helix, primase lays RNA primers, and DNA polymerase extends 5' to 3'. The leading strand is continuous; the lagging strand forms Okazaki fragments joined by DNA ligase.

Cardiac output formula

Cardiac output equals heart rate multiplied by stroke volume. At rest, roughly 75 beats per minute times 70 mL per beat gives about 5.25 litres per minute.

Insulin and glucagon

Insulin from beta cells lowers blood glucose by promoting cellular uptake and glycogen synthesis. Glucagon from alpha cells raises it through glycogenolysis and gluconeogenesis. The two hormones act antagonistically.

Kinematic equations constant acceleration

For constant acceleration: v = v0 + at, s = v0 t + at^2/2, and v^2 = v0^2 + 2as. Near Earth's surface free fall uses g approximately 9.8 m/s^2 directed downward.

Forces on an inclined plane

On a frictionless incline of angle theta, the component of weight along the slope is mg sin(theta) and the normal reaction is mg cos(theta). Friction adds a force of magnitude mu times the normal.

Momentum and energy in collisions

Total momentum is conserved in all collisions. Kinetic energy is conserved only in elastic collisions; inelastic collisions convert some kinetic energy into heat, sound or deformation.

Centripetal acceleration and force

For uniform circular motion, acceleration points to the centre with magnitude v^2/r or omega^2 r. The required centripetal force is mv^2/r, supplied by tension, gravity, friction or the normal force.

Period of a simple pendulum

A pendulum's period is T = 2 pi times the square root of L/g. For small amplitudes the period is independent of mass and amplitude, so a graph of T^2 against L is linear.

Snell's law and critical angle

Refraction obeys n1 sin(theta1) = n2 sin(theta2), with refractive index n = c/v. Total internal reflection occurs beyond the critical angle given by sin(theta_c) = n2/n1 when n1 exceeds n2.

Resistors in series and parallel

In series, resistances add directly and the current is the same through each. In parallel, the reciprocals add, so 1/R = 1/R1 + 1/R2, and the voltage is the same across each branch.

Faraday and Lenz laws

The induced emf equals the negative rate of change of magnetic flux, emf = -d(Phi)/dt, with flux Phi = BA cos(theta). Lenz's law states the induced current opposes the change that produced it.

Mole and molar volume

The number of moles equals mass divided by molar mass, and also particles divided by Avogadro's constant, 6.022e23 per mole. One mole of any gas occupies 22.4 L at 273 K and 1 atm.

Electron configuration order

Orbitals fill in order of increasing energy: 1s 2s 2p 3s 3p 4s 3d. The Pauli exclusion principle limits each orbital to two electrons, and Hund's rule keeps unpaired electrons parallel.

VSEPR geometry prediction

Electron pairs repel and spread out. Two pairs give linear, three trigonal planar, four tetrahedral, four with one lone pair trigonal pyramidal, and four with two lone pairs bent.

pH and strong versus weak acids

pH equals minus the logarithm of the hydronium concentration, and pH plus pOH equals 14 at 25 C. Strong acids dissociate completely; weak acids reach equilibrium described by their Ka value.

Le Chatelier principle

A system at equilibrium shifts to oppose a disturbance. Adding reactant shifts forward, raising pressure favours fewer gas moles, raising temperature favours the endothermic direction, and catalysts do not shift the position.

Galvanic cell electrode signs

In a galvanic cell, oxidation occurs at the anode, which is the negative electrode, and reduction at the cathode, the positive electrode. Cell emf equals cathode potential minus anode potential.

Hess law and bond enthalpies

Enthalpy change is independent of the route taken, so stepwise enthalpies can be added. Reaction enthalpy also equals bond energies broken minus bond energies formed; exothermic reactions have negative delta H.

Organic functional group recognition

Alkenes contain a C=C double bond, alcohols an -OH group, aldehydes a terminal -CHO, ketones a C=O between carbons, carboxylic acids -COOH, and esters a -COO- linkage between two carbon groups.

Earth's internal layers

The crust is oceanic basalt or continental granite, the mantle is peridotite to 2900 km depth, and the core is iron-nickel with a liquid outer part and solid inner part. The Moho separates crust from mantle.

Plate boundary types

Divergent boundaries create new lithosphere at ridges with shallow quakes. Convergent boundaries produce subduction, trenches, volcanic arcs and deep quakes. Transform boundaries produce strike-slip faults such as the San Andreas.

P and S seismic waves

P waves are longitudinal and fastest, travelling through solids and liquids. S waves are transverse, slower, and cannot pass liquids, which demonstrates that the outer core is liquid.

Three rock types

Igneous rocks solidify from magma, plutonic coarse and volcanic fine grained. Sedimentary rocks form by deposition and lithification, often with strata and fossils. Metamorphic rocks recrystallise under heat and pressure, often with foliation.

Relative dating principles

Superposition places older strata below younger ones; original horizontality and lateral continuity constrain deformation; cross-cutting features are younger than what they cut; faunal succession allows correlation using index fossils.

Geological eras and extinctions

The Precambrian precedes 541 Ma, the Palaeozoic ends with the Permian-Triassic extinction at 252 Ma, the Mesozoic ends with the Cretaceous-Palaeogene extinction at 66 Ma, and the Cenozoic continues to the present.

Accuracy versus precision

Accuracy is closeness to the true value; precision is agreement among repeated measurements. Random errors reduce precision and are averaged out, while systematic errors reduce accuracy and require calibration.

Experimental variables

The independent variable is deliberately changed, the dependent variable is measured in response, and controlled variables are held constant. A control group receives no treatment so the effect can be isolated.

Uncertainty propagation rules

When adding or subtracting, absolute uncertainties add. When multiplying or dividing, relative or percentage uncertainties add. The final result is reported as value plus or minus uncertainty with matching significant figures.