Mixed Deck — All A-LEVEL Topics Flashcards

In a transformer, the primary coil has 200 turns and the secondary has 50 turns. If the input is 240V, what is the output?

Answer: 60V

Vs/Vp = Ns/Np → Vs = 240 × (50/200) = 240 × 0.25 = 60V. This is a step-down transformer.

What is the 'tragedy of the commons'?

Answer: When individuals, acting in self-interest, deplete shared resources, leading to collective harm — illustrating the need for regulation of common goods

Garrett Hardin's 'tragedy of the commons' describes how individuals rationally exploit shared resources (fisheries, atmosphere) for personal gain, eventually depleting them for everyone — justifying collective governance of common goods.

What is the immune response involving B lymphocytes?

Answer: B cells produce specific antibodies that bind to antigens on pathogens, marking them for destruction (humoral immunity)

B lymphocytes, when activated by antigens, differentiate into plasma cells that produce large quantities of specific antibodies. These antibodies neutralise pathogens, opsonise them for phagocytosis, or activate complement.

What happens to the resistance of a metallic conductor as its temperature increases?

Answer: Resistance increases because increased thermal vibrations impede electron flow

In metals, higher temperature causes greater lattice vibrations, which increase collisions with conduction electrons, thus increasing resistance. This is why metals have a positive temperature coefficient of resistance.

What type of reaction is the conversion of glucose to ethanol by yeast?

Answer: Fermentation (anaerobic)

Yeast converts glucose to ethanol and CO₂ under anaerobic conditions by fermentation: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂.

What is the Lorenz curve used to measure?

Answer: Income inequality within a country

The Lorenz curve plots the cumulative share of income earned against the cumulative share of population. The further the curve from the 45° line, the greater the income inequality.

Find ∫ x e^x dx.

Answer: xe^x - e^x + C

Integration by parts: u=x, dv=e^x dx. du=dx, v=e^x. ∫xe^x dx = xe^x - ∫e^x dx = xe^x - e^x + C = e^x(x-1) + C. Both options A and D are the same.

What is the sum of the first 10 terms of the arithmetic series 3, 7, 11, 15, ...?

Answer: 210

Using S_n = n/2 × [2a + (n-1)d], where a = 3, d = 4, n = 10: S_10 = 10/2 × [2(3) + (9)(4)] = 5 × [6 + 36] = 5 × 42 = 210.

What is the photoelectric effect?

Answer: Emission of electrons from a metal surface when light of sufficient frequency is incident on it

The photoelectric effect is the emission of electrons from a metal surface when light above the threshold frequency is incident on it — evidence for the particle nature of light (photons).

What is 'comparative advantage' in international trade?

Answer: A country's ability to produce a good at a lower opportunity cost than another country

Comparative advantage means a country can produce a good at a lower opportunity cost relative to another country. Even if one country is better at producing everything (absolute advantage), trade based on comparative advantage benefits both.

What is the Calvin cycle in photosynthesis?

Answer: The light-independent reaction where CO₂ is fixed and reduced to form glucose using ATP and NADPH from the light reactions

The Calvin cycle (light-independent reactions) occurs in the stroma of chloroplasts. CO₂ is fixed by RuBisCO, then reduced using ATP and NADPH to eventually produce glucose.

What is the order of reaction if doubling the concentration of A doubles the rate?

Answer: First order

If rate ∝ [A]¹, doubling [A] doubles the rate. This is first order with respect to A.

What is the sum to infinity of a geometric series with first term 4 and common ratio 1/3?

Answer: 6

S∞ = a/(1-r) = 4/(1 - 1/3) = 4/(2/3) = 4 × 3/2 = 6. Valid since |r| = 1/3 < 1.

What is the AD-AS model used for?

Answer: Analysing macroeconomic equilibrium and the effects of policies on national income, price level, and employment

The AD-AS (Aggregate Demand-Aggregate Supply) model analyses macroeconomic equilibrium, showing how changes in AD or AS affect national income (real GDP), price level, and employment.

What does 'Lenz's Law' state?

Answer: The induced current is in such a direction that its magnetic effect opposes the change causing it

Lenz's Law states that the direction of the induced current is such that it opposes the change in flux that produced it — a consequence of conservation of energy.

What is the difference between fission and fusion?

Answer: Fission splits heavy nuclei; fusion combines light nuclei to release energy

Nuclear fission splits heavy nuclei (e.g., uranium-235) into smaller fragments, releasing energy. Nuclear fusion combines light nuclei (e.g., hydrogen isotopes) to form heavier nuclei, releasing even more energy per nucleon.

Find the exact value of ∫₀^(π/2) sin(x) dx.

Answer: 1

∫₀^(π/2) sin(x) dx = [-cos(x)]₀^(π/2) = -cos(π/2) + cos(0) = 0 + 1 = 1.

Solve ln(x + 1) - ln(x) = 2.

Answer: x = 1/(e²-1)

ln((x+1)/x) = 2 → (x+1)/x = e² → 1 + 1/x = e² → 1/x = e²-1 → x = 1/(e²-1).

What is the mechanism for the reaction of benzene with bromine in the presence of AlBr₃?

Answer: Electrophilic substitution

AlBr₃ acts as a Lewis acid catalyst, generating Br⁺ (electrophile). Benzene undergoes electrophilic substitution to maintain aromaticity, replacing H with Br.

What does 'meritocracy' mean in the context of social mobility?

Answer: A system where advancement is based on individual merit — talent, effort, and achievement — regardless of background

Meritocracy holds that people advance based on their abilities and efforts. In the GP context, students debate whether Singapore's meritocracy is truly fair or whether structural inequalities persist.