Biology Enzymes SZABMU 2023
PMDC Verified Question 27 of 79
Lock and Key Model for enzyme action proposed by Emil Fischer suggests that:
A
Enzymes can modify their active sites
B
Enzymes are unbiased for the substrate
C
An enzyme can catalyze variety of reactions
D
Enzymes are restricted to one reaction type
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: Enzymes are restricted to one reaction type
Concept:

The foundational premise of Emil Fischer's 1894 model is extreme structural rigidity. A physical lock cannot change its shape to accommodate different keys.

Solution:

  • The Lock and Key model dictates that the active site is a rigid, pre-formed structure that exactly matches only one specific substrate.
  • Because it can physically only bind to one specific chemical, the enzyme is completely restricted to one reaction type.


Why other options are incorrect:

Modifying active sites is the hallmark of Koshland's Induced Fit model. Catalyzing a variety of reactions or being 'unbiased' directly violates the strict specificity of the Lock and Key concept.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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