Both enzymes and inorganic catalysts speed up a reaction by lowering its activation energy, and both stay unchanged at the end. But enzymes are protein biocatalysts that work fast at mild body conditions (around 37°C, near-neutral pH), while inorganic catalysts (like platinum) need high temperature and high pressure. The NCERT one-line difference to remember: high heat DAMAGES enzymes (above ~40°C) but HELPS inorganic catalysts. Memory hook: "Enzymes are gentle, metals are tough."
Both catalysts lower the activation energy (Ea) and turn substrate S into product P. The difference: enzymes are proteins that work at mild body conditions and are damaged by heat, while inorganic catalysts are non-protein and need high temperature and pressure.
Your doubts, answered
What is the ONE major difference NCERT highlights between enzymes and inorganic catalysts?
NCERT says enzymes differ from inorganic catalysts in many ways, but one major difference needs mention: inorganic catalysts work efficiently at HIGH temperatures and HIGH pressures, while enzymes get DAMAGED at high temperatures (say above 40°C). This is the exact line NEED asks about, so learn it word for word.
Do inorganic catalysts also lower activation energy, or only enzymes?
Both do. Every catalyst, enzyme or inorganic, works by lowering the activation energy barrier so the reaction goes faster. Lowering activation energy is NOT a difference. The difference is the conditions they need (temperature, pressure) and the fact that enzymes are proteins made by living cells.
Why do enzymes get damaged at high temperature but inorganic catalysts do not?
Enzymes are proteins with a folded 3D shape. Heat above ~40°C denatures (unfolds) the protein, so the active site is destroyed and activity is lost. Inorganic catalysts (like platinum, iron) are simple non-protein substances with no delicate folded shape, so high heat only helps them. Note: enzymes from hot-spring microbes stay stable up to 80–90°C (thermal stability).
Are enzymes really that much faster than inorganic catalysts?
Yes, enzymes are extremely powerful. NCERT gives carbonic anhydrase: without the enzyme only about 200 molecules of H2CO3 form in one hour, but with the enzyme about 600,000 molecules form every second. That is roughly 10 million times faster. This huge rate boost at mild body conditions is why enzymes are special.
Is an enzyme a catalyst? Is every catalyst an enzyme?
Every enzyme IS a catalyst (a biological one, a biocatalyst). But NOT every catalyst is an enzyme. Inorganic catalysts like platinum or nickel are catalysts but are not enzymes. Enzymes are made by living cells and almost all are proteins (a few RNA enzymes = ribozymes).
⚠️ The NEET trap ✗ Enzymes speed up reactions by RAISING the activation energy, and inorganic catalysts do not lower it at all. ✓ Both enzymes and inorganic catalysts LOWER the activation energy. The real differences are chemical nature (enzyme = protein) and working conditions (enzymes need mild temperature/pH; inorganic catalysts tolerate high heat and pressure). 🧠 NEET loves swapping 'lower' with 'raise'. A catalyst NEVER raises activation energy. It always brings the barrier DOWN for both enzyme and inorganic types.
Real NEET questions
NEET 2016 Phase 2
Which of the following describes the given graph correctly? (Reaction-coordinate / potential-energy profile with activation energies labelled 'A' and 'B'.)
A · Endothermic reaction with energy A in presence of enzyme and B in absence of enzyme
B · Exothermic reaction with energy A in presence of enzyme and B in absence of enzyme ✓
C · Endothermic reaction with energy A in absence of enzyme and B in presence of enzyme
D · Exothermic reaction with energy A in absence of enzyme and B in presence of enzyme
Solution: The product P sits lower than the substrate S, so the reaction is exothermic. A catalyst (here an enzyme) lowers the activation-energy barrier, so the SMALLER barrier 'A' is with enzyme and the LARGER barrier 'B' is without enzyme. This shows both a catalyst lowers activation energy and how an enzyme cuts the barrier.
Solved Biomolecules NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Name the enzyme NCERT uses to show enzyme power over an uncatalysed reaction.
Carbonic anhydrase. Without it, about 200 molecules of carbonic acid (H2CO3) form per hour; with it, about 600,000 molecules form per second, roughly 10 million times faster.
Do enzymes get used up in a reaction?
No. Like all catalysts, enzymes are not consumed. After releasing the product, the free enzyme is ready to bind another substrate molecule.
What is a biocatalyst?
A biocatalyst is a catalyst produced by a living cell, i.e. an enzyme. Almost all enzymes are proteins; a few are RNA molecules called ribozymes.
At what temperature do most human enzymes work best, and when are they destroyed?
Most work best near body temperature (about 37°C) and near-neutral pH. They are denatured and lose activity at high temperatures, generally above 40°C, because the protein unfolds.
