Top 15 NEET Mistakes in CB-02

Error 1: "Enzymes change the equilibrium of reactions." Correction: Enzymes NEVER change equilibrium or $\Delta G$. They only lower activation energy and speed up the rate at which equilibrium is reached.

Error 2: "All enzymes are proteins." Correction: Most enzymes are proteins, but RIBOZYMES are RNA molecules with catalytic activity (Thomas Cech/Sidney Altman, Nobel 1989). Classic NEET trap.

Error 3: "Competitive inhibitors decrease Vmax." Correction: Competitive inhibitors increase Km (apparent) but leave Vmax UNCHANGED. Non-competitive inhibitors decrease Vmax.

Error 4: "Glycogen is a plant storage polysaccharide." Correction: Starch is the plant storage polysaccharide. Glycogen is the ANIMAL storage polysaccharide ("animal starch").

Error 5: "Cellulose and starch are both made of glucose with the same bonds." Correction: Both are made of glucose but with DIFFERENT linkages: starch uses alpha-glycosidic; cellulose uses beta-glycosidic. This difference makes cellulose indigestible.

Error 6: "Peptide bonds stabilize secondary protein structure." Correction: Peptide bonds define PRIMARY structure. Secondary structure is stabilized by HYDROGEN BONDS between backbone groups.

Error 7: "Disulphide bonds are at the secondary structure level." Correction: Disulphide bonds (between cysteine R-groups) stabilize TERTIARY (and sometimes quaternary) structure.

Error 8: "Uracil is found in DNA." Correction: Uracil is found in RNA. DNA has thymine. A-T pairing in DNA; A-U pairing in RNA.

Error 9: "A lower Km means lower enzyme efficiency." Correction: Lower Km means HIGHER affinity (the enzyme binds substrate at lower concentrations, reaching ½ Vmax at a lower [S]).

Error 10: "Lactose = galactose + galactose." Correction: Lactose = galactose + GLUCOSE. Maltose = glucose + glucose.

Error 11: "Haemoglobin has secondary structure (alpha-helices)." Correction: While haemoglobin's individual chains DO have alpha-helices (secondary structure), the key NEET answer for haemoglobin is QUATERNARY structure (4 subunits: 2α + 2β).

Error 12: "Sucrose is a reducing sugar." Correction: Sucrose is a NON-reducing sugar. Its glycosidic bond involves both reducing ends (C-1 of glucose and C-2 of fructose), eliminating free aldehyde/ketone groups.

Error 13: "Chitin is found in plant cell walls." Correction: Cellulose is in plant cell walls. Chitin is in FUNGAL cell walls and ARTHROPOD exoskeletons.

Error 14: "N$AD^{+}$ is a prosthetic group." Correction: N$AD^{+}$ is a COENZYME (loosely bound, organic). Haem is a prosthetic group (tightly/covalently bound).

Error 15: "Enzymes lower activation energy by consuming ATP." Correction: Most enzymes lower activation energy WITHOUT consuming ATP. Ligases use ATP to FORM bonds (a different concept). Catalysts in general are not consumed.