Identify the correct statements regarding enzymes

• Option A: Enzymes can normally function at very high temperature ($$T \sim 1000 \text{ K}$$)

  Enzymes are proteinaceous molecules. At high temperatures (typically above $$310\text{--}320 \text{ K}$$ or $$37\text{--}45^\circ\text{C}$$), the weak hydrogen bonds and intramolecular forces maintaining their tertiary structure break down. This process, known as denaturation, destroys their catalytic capability. They definitely cannot function at extreme temperatures like $$1000 \text{ K}$$.

  Result: INCORRECT




• Option B: Enzymes are specific biological catalysts that possess well-defined active sites

  Enzymes feature highly specific three-dimensional cavities on their surfaces called active sites. These sites contain specialized functional groups (like $$-\text{COOH}$$, $$-\text{NH}_2$$, $$-\text{OH}$$) that match the geometry and chemical nature of specific substrate molecules, following a "Lock and Key" or "Induced Fit" mechanism. This makes them extraordinarily selective and efficient biological catalysts.

  Result: CORRECT




• Option C: Enzymes are specific biological catalysts that cannot be poisoned

  Enzymes are highly susceptible to inhibitors and poisons. Heavy metal ions (like $$\text{Hg}^{2+}$$, $$\text{Pb}^{2+}$$, $$\text{Ag}^+$$) or certain toxic compounds can bind to the active site or alter the conformation of the enzyme, completely shutting down its catalytic activity.

  Result: INCORRECT




• Option D: Enzymes are normally heterogeneous catalysts that are very specific in their action

  Enzymes generally function in the aqueous environment of cells, where both the enzyme and the substrates are dissolved in the same liquid phase. Therefore, enzymatic reactions are primary examples of homogeneous catalysis rather than heterogeneous catalysis.

  Result: INCORRECT

Conclusion:

The only scientifically accurate statement is that enzymes possess well-defined active sites that allow them to function as highly specific biological catalysts.

Answer: Option B