All 84 decoded questions of ESAT 2021, in paper order. · A question can reward more than one move, so the counts overlap.
ENGAA 2021 Section 1, Part B (Mathematics questions) 20 decoded 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 The paper at a glance, coloured by move. Click a square to open its question; empty squares are not decoded yet.
61 Natural selection edits pre-existing random variation, the environment never writes it Key method Biology Inheritance, Variation & Evolution 4 other sittings Same method, other sittings
62 Prokaryote versus eukaryote: the defining feature contrast (wall, nucleus, mitochondria, chloroplasts) Animal cells never have a cell wall or chloroplasts: use it as an instant eliminator Pavlov Biology Cells 6 other sittings Same method, other sittings
63 The three osmosis definition traps examiners plant in statements Movement against the concentration gradient means active transport and needs energy Key method Biology Membrane Transport, Cell Division & Reproduction 4 other sittings Same method, other sittings
64 Blood glucose control: insulin stores, glucagon and adrenaline release, the loop is negative feedback Pavlov Biology Animal Physiology: Systems, Homeostasis & Disease 1 other sitting Same method, other sittings
65 Separate chromosome, DNA molecule and strand, and watch for the replication doubling Every body cell shares one genome, and the male gamete fixes the sex Mutation is the exception that breaks any absolute genetic claim Key method Biology Membrane Transport, Cell Division & Reproduction 5 other sittings Same method, other sittings
66 Weigh the modal word: always or must needs certainty, could or may needs only one plausible mechanism Key method Biology Ecology & Plant Physiology 3 other sittings Same method, other sittings
67 A rise-then-plateau curve means a factor is now limiting; plateau height is set by total substrate Biology arithmetic reflexes: percentage over the original, rate as amount over time, area as radius squared An enzyme is a protein catalyst, not a living thing: eliminate options that contradict its nature Key method Biology Enzymes 5 other sittings Same method, other sittings
68 On numbered-statement items, bin the clause that reverses cause, sign or proportionality Respiration signature in blood; hard exercise adds lactate and lowers pH Key method Biology Animal Physiology: Systems, Homeostasis & Disease 3 other sittings Same method, other sittings
69 Probability of a specific sex and a specific genotype: multiply the two independent chances A lethal or non-surviving genotype: delete it and re-read the ratio among survivors A recessive phenotype fixes the genotype, a dominant phenotype needs a test cross Key method Biology Inheritance, Variation & Evolution 6 other sittings Same method, other sittings
70 DNA base arithmetic: pairing rules bind the whole molecule, never a single strand Key method Biology DNA, Protein Synthesis & Gene Technology 3 other sittings Same method, other sittings
71 Osmosis moves water toward the more concentrated solution The cell wall decides whether a cell bursts, and the vacuole holds cell sap Pavlov Biology Membrane Transport, Cell Division & Reproduction 6 other sittings Same method, other sittings
72 Carbon cycle diagrams: follow the arrows and check each product for carbon and hydrogen Key method Biology Ecology & Plant Physiology 2 other sittings Same method, other sittings
73 Magnification equals image size over actual size: fix the units first, then let the order of magnitude choose Key method Biology Cells 1 other sitting Same method, other sittings
74 Monohybrid cross Aa x Aa gives a 1:2:1 genotype ratio and a 3:1 phenotype ratio Probability of a specific sex and a specific genotype: multiply the two independent chances Read dominance off the pedigree first, then fix which parents must be heterozygous Tunnel Biology Inheritance, Variation & Evolution 6 other sittings Same method, other sittings
75 Read a stem cell division by counting what the two daughters are Key method Biology Membrane Transport, Cell Division & Reproduction 1 other sitting Same method, other sittings
76 Temperature and pH curves peak at an optimum; a concentration curve plateaus Key method Biology Enzymes 2 other sittings Same method, other sittings
77 Match each defence to its signature; antibiotics hit bacteria only, red cells are not phagocytic Pavlov Biology Animal Physiology: Systems, Homeostasis & Disease 1 other sitting Same method, other sittings
78 Mitosis keeps the chromosome number and makes two cells, meiosis halves it and makes four Key method Biology Membrane Transport, Cell Division & Reproduction 6 other sittings Same method, other sittings
79 One person, one genome: division type, stem cells, and same DNA but different proteins Pavlov Biology Cells 2 other sittings Same method, other sittings
80 Ecological abundance: frequency is presence in quadrats, density is count per area, and both need a random sample Key method Biology Ecology & Plant Physiology 5 other sittings Same method, other sittings
NSAA 2021 Section 1 Part B (ESAT Physics) 20 decoded 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 The paper at a glance, coloured by move. Click a square to open its question; empty squares are not decoded yet.
41 Read the reactivity order off the behaviour, do not recall a fixed list Key method Chemistry Electrolysis & Metals 2 other sittings Same method, other sittings
42 Read a nuclide symbol into protons, neutrons and electrons Isoelectronic species share an electron count but differ in protons Pavlov Chemistry Atomic Structure, Bonding & the Periodic Table 5 other sittings Same method, other sittings
43 Relative atomic mass as an abundance-weighted mean, forwards or reversed Tunnel Chemistry Atomic Structure, Bonding & the Periodic Table 5 other sittings Same method, other sittings
44 Classify the structure and bonding, then read off the property Recall Group 1 and Group 17 trends whole, without deriving them Key method Chemistry Atomic Structure, Bonding & the Periodic Table 7 other sittings Same method, other sittings
45 Thermometric graph: peak is neutralisation, the fall is only cooling Key method Chemistry Rates of Reaction & Energetics 1 other sitting Same method, other sittings
46 Addition-polymer repeat unit: two backbone carbons, side groups kept Key method Chemistry Organic Chemistry, Separation & Analysis 2 other sittings Same method, other sittings
47 Standard qualitative tests to identify ions Pavlov Chemistry Organic Chemistry, Separation & Analysis 2 other sittings Same method, other sittings
48 Oxidation states sum to the overall charge, capped by the group number Key method Chemistry Chemical Reactions, Acids, Bases & Redox 2 other sittings Same method, other sittings
49 Classic organic-product distractors the examiner offers Esterification balances by conservation of mass, add 18 for water Key method Chemistry Organic Chemistry, Separation & Analysis 2 other sittings Same method, other sittings
50 Balance a skeleton equation one element at a time, most constrained first Tunnel Chemistry Chemical Reactions, Acids, Bases & Redox 3 other sittings Same method, other sittings
51 Rf equals spot distance over solvent-front distance Interpreting a chromatogram: purity, identity, mobility and phases Pavlov Chemistry Organic Chemistry, Separation & Analysis 6 other sittings Same method, other sittings
52 Name an unknown product from the atoms left over after the known products Key method Chemistry Chemical Reactions, Acids, Bases & Redox 2 other sittings Same method, other sittings
53 Diprotic acid reflex: sulfuric and ethanedioic acid react two to one with a monobasic base Pavlov Chemistry Quantitative Chemistry 2 other sittings Same method, other sittings
54 Calorimetry: q equals mc delta T, then divide by the limiting moles Tunnel Chemistry Rates of Reaction & Energetics 3 other sittings Same method, other sittings
55 Bond-energy balance: broken minus formed, counting every bond Exploit the bond-energy option list: sign, factor and phantom bonds Tunnel Chemistry Rates of Reaction & Energetics 4 other sittings Same method, other sittings
56 Read the balanced equation directly in gas volumes, and track the change in the number of gas molecules Limiting reagent by moles over coefficient, and the graph plateau marks the exact stoichiometric point Key method Chemistry Quantitative Chemistry 3 other sittings Same method, other sittings
57 Electron accounting: turn charge into moles, then read every amount off the half-equations Tunnel Chemistry Electrolysis & Metals 4 other sittings Same method, other sittings
58 Mass by difference: the component asked for is the leftover, and its molar mass is often a decoy Molar gas volume both ways, and the two traps: cubic decimetres versus cubic centimetres, and diatomic gases Key method Chemistry Quantitative Chemistry 3 other sittings Same method, other sittings
59 Mass by difference: the component asked for is the leftover, and its molar mass is often a decoy Pin exactly what is asked: the examiner plants the natural intermediate value as an option Precipitation gravimetry: only the ion that forms the solid counts, ignore the spectators Key method Chemistry Quantitative Chemistry 5 other sittings Same method, other sittings
60 Cumulative product only rises, and each interval adds less Key method Chemistry Rates of Reaction & Energetics only this sitting Same method, other sittings
This one has only struck here so far.
NSAA 2021 Section 1, Part A (Mathematics questions) 14 decoded 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 The paper at a glance, coloured by move. Click a square to open its question; empty squares are not decoded yet.
1 Distributing Outer Powers Pavlov Pure Algebra, Functions & Graphs 1 other sitting Same method, other sittings
2 Algebraic Fraction Simplification Pavlov Pure Algebra, Functions & Graphs 6 other sittings Same method, other sittings
3 Rearranging Complex Formulas Pavlov Pure Algebra, Functions & Graphs 4 other sittings Same method, other sittings
4 Perpendicular lines: the product of their gradients is -1 Pavlov Pure Coordinate Geometry 2 other sittings Same method, other sittings
5 3D solids: equating volumes and surface areas algebraically Tunnel Pure Geometry 5 other sittings Same method, other sittings
6 Treat complex terms as single variables in simultaneous equations Pavlov Pure Number & Units only this sitting Same method, other sittings
This one has only struck here so far.
7 Successive percentage changes as a product of decimal multipliers Pavlov Pure Ratio & Proportion 5 other sittings Same method, other sittings
9 Overlay a coordinate system for complex intersecting shapes Key method Pure Geometry 5 other sittings Same method, other sittings
11 Root Gap from the Discriminant Key method Pure Algebra, Functions & Graphs 2 other sittings Same method, other sittings
12 Systematic enumeration for small discrete sums Pavlov Prob & Stats Probability & Statistics 2 other sittings Same method, other sittings
14 Circle theorems: angle chasing Tunnel Pure Geometry 2 other sittings Same method, other sittings
15 Set up algebraic probability trees Tunnel Prob & Stats Probability & Statistics 4 other sittings Same method, other sittings
19 Sanity check algebraic word problems by scaling Key method Pure Number & Units only this sitting Same method, other sittings
This one has only struck here so far.
20 Sketching and Counting Intersections Key method Pure Trigonometry only this sitting Same method, other sittings
This one has only struck here so far.
NSAA 2021 Section 1, Part C (Chemistry questions) 10 decoded 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 The paper at a glance, coloured by move. Click a square to open its question; empty squares are not decoded yet.
21 Rewriting Before Differentiating Pavlov Pure Differentiation 1 other sitting Same method, other sittings
23 The Difference of Partial Sums Pavlov Pure Sequences & Series only this sitting Same method, other sittings
This one has only struck here so far.
25 Quadratics in Disguise Key method Pure Algebra, Functions & Graphs 3 other sittings Same method, other sittings
27 Sector and Segment Mechanics Tunnel Pure Trigonometry 2 other sittings Same method, other sittings
29 Sum of Logarithms → Product of Arguments Pavlov Pure Exponentials & Logarithms 1 other sitting Same method, other sittings
31 Ordering Trig Values without a Calculator Key method Pure Trigonometry only this sitting Same method, other sittings
This one has only struck here so far.
33 Sub-Progressions of a Geometric Series Key method Pure Sequences & Series only this sitting Same method, other sittings
This one has only struck here so far.
35 System to Single Quadratic Pavlov Pure Algebra, Functions & Graphs 2 other sittings Same method, other sittings
37 Rationalise the denominator using the conjugate Tunnel Pure Number & Units 2 other sittings Same method, other sittings
39 Geometric Optimisation Tunnel Pure Differentiation 2 other sittings Same method, other sittings
NSAA 2021 Section 1, Part D (Biology questions) 20 decoded 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 The paper at a glance, coloured by move. Click a square to open its question; empty squares are not decoded yet.
21 Find the current first: it is the hub of every electrical chain Pavlov Physics Electricity & Magnetism 4 other sittings Same method, other sittings
22 When only a ratio is asked, form the ratio and let the unknowns cancel Decide the direction of the change first, then read the spread of the options Sealed gas at constant temperature: density follows the pressure directly Key method Physics Matter 4 other sittings Same method, other sittings
23 Transformers: voltage by turns ratio, current by power, never turns ratio for a non ideal current Tunnel Physics Electricity & Magnetism 3 other sittings Same method, other sittings
24 Steady motion is a free equation, and after a perturbation only the change is unbalanced Choose the system: the whole assembly for the acceleration, one body for an internal force Key method Physics Kinematics & Forces 4 other sittings Same method, other sittings
25 In a vacuum every electromagnetic wave shares one speed, so frequency and wavelength are strictly inverse Use the relative speed and Doppler direction, never the still values, when source or observer moves Pavlov Physics Waves, Sound & the Electromagnetic Spectrum 3 other sittings Same method, other sittings
26 Atomic bookkeeping: protons are the element, neutrons are the isotope, electrons set the charge Key method Physics Radioactivity 2 other sittings Same method, other sittings
27 Springs: the extension is not the length, and the stored energy is half of what you expect Key method Physics Energy, Work & Momentum 3 other sittings Same method, other sittings
28 In a two state question, lock the invariant from state one before touching state two When the resistances are identical or never given, call each one R and let it cancel A closed ideal switch is a plain wire: redraw before you compute Key method Physics Electricity & Magnetism 6 other sittings Same method, other sittings
29 Force from a momentum change: divide by the contact time, and double the speed for a bounce The second law gives the resultant force, but the question asks for a named one Tunnel Physics Energy, Work & Momentum 2 other sittings Same method, other sittings
30 Use the relative speed and Doppler direction, never the still values, when source or observer moves Key method Physics Waves, Sound & the Electromagnetic Spectrum 1 other sitting Same method, other sittings
31 For a non ohmic component the graph is its Ohm law: the circuit picks the axis Which graph questions: one numerical anchor plus one shape argument Key method Physics Electricity & Magnetism 4 other sittings Same method, other sittings
32 Force on a current: the work is deciding what B, I and L really are Key method Physics Electricity & Magnetism 4 other sittings Same method, other sittings
33 Classify a wave on the spectrum by converting band edges with the wave equation Tunnel Physics Waves, Sound & the Electromagnetic Spectrum 3 other sittings Same method, other sittings
34 Pick the SUVAT equation that skips the variable you were not asked about Tunnel Physics Kinematics & Forces 1 other sitting Same method, other sittings
35 Energy audit on a heated body: supplied, stored, lost Which expression questions: settle them by units and by one variable at a time Tunnel Physics Thermal Physics 3 other sittings Same method, other sittings
36 Energy lost, wasted or done against drag is the input total minus the useful total Key method Physics Energy, Work & Momentum 3 other sittings Same method, other sittings
37 Half-life arithmetic: work in powers of one-half, never in logarithms Decay conserves atoms one for one: daughter equals initial daughter plus parent decayed Pavlov Physics Radioactivity 6 other sittings Same method, other sittings
38 Ice and water mixtures: test the melting budget before writing any equation Method of mixtures: heat lost equals heat gained, and some given data is meant to be unused Key method Physics Thermal Physics 2 other sittings Same method, other sittings
39 Let the option list choose your units, and kill options by dimensions Decide the direction of the change first, then read the spread of the options Liquid pressure counts only what lies above the point, layer by layer Key method Physics Matter 5 other sittings Same method, other sittings
40 Turn measured times into distances with the right geometric factor for reflected or multi-speed signals Key method Physics Waves, Sound & the Electromagnetic Spectrum 3 other sittings Same method, other sittings
