Egypt STEM Schools Entrance Exam cheat sheet

Integrated admission foundations: math, biology, chemistry, physics, english, formal

• Factor completely: GCF first, then grouping, special products, or trinomial methods.

• Cancel factors only; terms in a sum cannot be canceled.

• 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.

• 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.

• 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.

• 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.

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

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

• 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.

• PCR copies a selected DNA region; ideal N0 times 2^n requires perfect doubling.

• Positive, no-template and extraction controls test different potential failures.

• Relative atomic mass is an abundance-weighted mean of isotope masses, calculated from mass-spectrum data.

• Across a period effective nuclear charge rises, so radius falls and ionisation energy and electronegativity rise.

• n = m/M, n = cV (V in dm3) and n = V/24.0 for gases at RTP are the three key conversions.

• The limiting reagent is the one with the smallest moles ÷ coefficient; product amount depends on it.

• Functional group priority determines the suffix and numbering in IUPAC names.

• 2,4-DNP is used for suitable aldehyde/ketone carbonyl tests; reducing tests have exceptions and must be interpreted with the supplied structure and conditions.

• Acidify with dilute HNO3 before adding AgNO3 for halide tests, and with dilute HCl before BaCl2 for sulfate tests.

• Flame colours: Li crimson, Na yellow, K lilac, Ca brick-red, Cu blue-green.