NEET PYQ-Focused High-Yield Points

The Non-Negotiable NEET Facts (Must Know):

1. Enzymes and activation energy: "Enzymes lower ACTIVATION ENERGY only" — this is asked every year. Options will include $\Delta G$, equilibrium constant, enthalpy — ALL wrong. Only activation energy is correct.

2. Ribozymes: "Which of the following is NOT a protein?" — Ribozyme (it is catalytic RNA). All other options (trypsin, insulin, collagen, keratin) will be proteins. This trap appears in every 2-3 NEET papers.

3. Competitive inhibition: "Malonate is a competitive inhibitor of succinate dehydrogenase" — classic paired fact. Effect: Km increases, Vmax unchanged, overcome by excess succinate.

4. Non-competitive inhibition: "Heavy metals ($Hg^{2+}$, $Pb^{2+}$) cause non-competitive inhibition." Effect: Km unchanged, Vmax decreases, cannot be overcome by substrate.

5. Disaccharide in milk: Lactose (galactose + glucose). Enzyme: lactase. Deficiency: lactose intolerance.

6. Haemoglobin = quaternary structure: 4 subunits (2 alpha + 2 beta). Prosthetic group = haem. This is the standard example for BOTH quaternary structure AND prosthetic groups.

7. Alpha vs Beta glycosidic bonds: Alpha = storage (starch, glycogen). Beta = structural (cellulose, chitin). NEVER confuse these — the most common glycosidic bond question in NEET.

8. Pepsin pH 2, Trypsin pH 8: These are REVERSED in trap MCQs. Always: pepsin = stomach = acidic = pH 2. Trypsin = intestine = alkaline = pH 8.

9. DNA base pairs: A-T = 2 H-bonds. G-C = 3 H-bonds. Higher GC content = more stable = higher melting temperature.

10. Apoenzyme + Cofactor = Holoenzyme: N$AD^{+}$ = coenzyme (not prosthetic group). Haem = prosthetic group (not coenzyme).