CSET Science - Life Sciences (215 & 217) cheat sheet

Condensation forms glycosidic, ester and peptide bonds; hydrolysis reverses them.

Reducing-sugar test interpretation requires suitable assay conditions and controls; hydrolysis can change sucrose test results.

Cellulose = β-1,4 glucose, straight H-bonded microfibrils; starch and glycogen = α-glucose.

Triglyceride = glycerol + 3 fatty acids; phospholipid = phosphate head + 2 tails, amphipathic.

Enzymes lower activation energy; specificity comes from active-site shape.

Simple reversible competition increases apparent Km without changing Vmax; pure noncompetitive inhibition lowers Vmax without changing Km.

Prokaryotes lack a membrane-bound nucleus; bacterial peptidoglycan walls are not universal and archaeal walls differ.

Fluid mosaic membranes contain a lipid bilayer and proteins; sterol and carbohydrate composition depends on the cell.

Facilitated diffusion is passive; primary active transport may use ATP directly and secondary transport uses a gradient.

Water potential ψ = ψs + ψp; water moves from higher (less negative) to lower ψ.

Mitosis (P-M-A-T) after S-phase replication maintains chromosome number.

Cytokinesis: cleavage furrow in animals, cell plate in plants.

A–T has 2 hydrogen bonds, G–C has 3; strands are antiparallel with 3′–5′ phosphodiester bonds.

Semi-conservative replication: helicase, DNA polymerase (5′→3′), ligase on the lagging strand.

The standard code is triplet and degenerate, nearly universal; AUG is a common start codon with biological exceptions.

Meiosis I separates homologues; crossing over in prophase I produces recombinants.

A test cross is with a homozygous recessive to reveal an unknown genotype.

Informative linked-locus crosses often give excess parentals; recombination percentage approximates short map distances, not all intervals exactly.

En modelos simples: competitivo reversible aumenta Km aparente sin cambiar Vmax; no competitivo puro baja Vmax sin cambiar Km.

Glucólisis en el citosol: 2 ATP netos, 2 NADH y 2 piruvato por glucosa.

Krebs: por vuelta 3 NADH, 1 FADH₂, 1 ATP y 2 CO₂; dos vueltas por glucosa.

Cadena respiratoria: quimiosmosis, ATP sintasa y O₂ como aceptor final de electrones.

Fase luminosa produce ATP y NADPH; el O₂ viene de la fotólisis del agua.

Ciclo de Calvin: RuBisCO fija CO₂ y consume ATP y NADPH para sintetizar glúcidos.

Hypothesis = testable prediction; theory = broad supported explanation; law = consistent regularity.

Independent variable is manipulated; dependent is measured; controls are held constant.

Random assignment supports experimental causal inference; an observed association alone does not establish causation.

Accuracy = closeness to truth; precision = repeatability.

Replication and sample size reduce the influence of random chance.

Atomic radius falls across a period, rises down a group

Ionic = electron transfer; covalent = sharing; metallic = delocalized electrons

VSEPR: 4 domains = tetrahedral; lone pairs compress angles

Compare the actual substances: hydrogen bonding, dipoles, polarizability and molecular size all affect intermolecular attractions

Limiting reagent is found by converting to moles and dividing by coefficients

pH is logarithmic: each unit is a tenfold change in [H+]

Resolve vectors before applying F = ma or the SUVAT equations

Momentum is a vector: conserve each component only when the corresponding net external impulse is zero

Equilibrium requires both zero resultant force and zero resultant moment

The centripetal component points to the centre; uniform circular motion has constant speed but changing velocity

SHM signature: a = −ω²x, giving T = 2π/ω

State g and sign conventions explicitly at the start of a solution

S-waves cannot pass liquids, revealing a liquid outer core

Divergent, convergent, and transform boundaries produce distinct features

Cross-cutting relationships and superposition establish relative ages

Igneous (intrusive vs extrusive), sedimentary, and metamorphic rocks cycle

Atmosphere: 78% N2, 21% O2; weather occurs in the troposphere

End-Cretaceous extinction linked to asteroid impact and iridium layer

Negative feedback reverses a deviation; positive feedback amplifies and must terminate.

Surface area to volume ratio drives the need for specialized exchange surfaces.

Pulmonary arteries carry deoxygenated blood away from the heart.

Xylem moves water up (cohesion–tension); phloem moves sugars by pressure flow.

Insulin lowers blood glucose; glucagon raises it - both are negative feedback.

Los virus son acelulares; los ciclos lítico y lisogénico son modelos de determinados bacteriófagos, no de todos los virus.

Retrovirus: retrotranscriptasa convierte ARN en ADN e integra el provirus.

Muchas bacterias tienen peptidoglicano; pared, plásmidos y otros rasgos deben comprobarse en cada organismo.

Linfocitos B → células plasmáticas → anticuerpos; CD4 ayudan y CD8 citotóxicos matan células infectadas.

La memoria adaptativa puede acelerar la respuesta; el predominio de IgG depende del contexto de la respuesta sistémica.

PCR: N0 por 2^n solo con duplicación ideal; en el mismo gel, ADN lineal pequeño suele migrar más lejos.

Selection, mutation, gene flow, and drift are the mechanisms of allele frequency change.

Hardy-Weinberg is an idealized null model; q squared gives recessive phenotype frequency only under the stated two-allele dominance and penetrance assumptions.

p + q = 1 and p² + 2pq + q² = 1; heterozygotes are 2pq.

Homologous structures reflect ancestry; analogous structures reflect convergent evolution.

Allopatric speciation can follow geographic isolation; prezygotic barriers act before fertilization.

Logistic growth includes carrying capacity K; exponential growth does not.

Energy flows through ecosystems; 10 percent trophic transfer is an illustrative approximation, not a universal efficiency.

Most organisms require fixed nitrogen; phosphorus lacks a major atmospheric reservoir in the standard school-cycle model.

Mark–recapture: N = (marked first × total second) ÷ marked second.

Primary succession starts on bare rock; secondary succession starts where soil remains.