The Question is from neet-botany biomolecules-biology , and it was created by the author Mr. NARESH KUMAR K

Question

In a metabolic pathway, enzyme A catalyzes the conversion of substrate X to intermediate Y. Enzyme B then catalyzes the conversion of Y to product Z. If a mutation in enzyme B renders it completely inactive, which of the following is MOST likely to occur?

Mr. NARESH KUMAR K · Accepted Answer

## CORE INFORMATION
✓ **Answer**: B
## CONCEPT FRAMEWORK
 **Primary Concept**: Metabolic pathways and enzyme function
 **Related Topics**: Enzyme kinetics, metabolic regulation, feedback inhibition
 **Prerequisites**: Understanding of enzyme-substrate interactions and the flow of metabolites in a pathway.
## SOLUTION PATHWAY
**Given Information**:
  * Enzyme A converts substrate X to intermediate Y ($X \overset{Enzyme\,A}{\longrightarrow} Y$)
  * Enzyme B converts intermediate Y to product Z ($Y \overset{Enzyme\,B}{\longrightarrow} Z$)
  * Enzyme B is completely inactive due to a mutation.
**Method & Steps**:
 1. Analyze the effect of enzyme B inactivation.
  Reasoning: Since enzyme B is inactive, the conversion of Y to Z will stop completely.  This will lead to a build-up of intermediate Y.
  Formula/Rule:  None directly applicable, this is a qualitative analysis.
 2. Consider the consequences of Y accumulation.
  Working: The accumulation of Y will not automatically increase the production of X.  In fact, the lack of Z might trigger feedback mechanisms (though not explicitly stated in the question) that could potentially decrease X production.
  Key Point: The pathway is blocked at the Y to Z step.
 3. Determine the overall effect on X, Y, and Z concentrations.
  Result:  Intermediate Y will accumulate because it's no longer being converted to Z.  The lack of conversion of Y to Z will result in a depletion of product Z.
  Verification: The logic follows the direct consequence of enzyme B inactivation.
 ## OPTION ANALYSIS
A :x: Increased production of substrate X is unlikely; the lack of product Z might even lead to a decrease in X production through feedback mechanisms.
B ✓: Accumulation of intermediate Y and depletion of product Z is the direct consequence of enzyme B being inactive.  The pathway is blocked at the Y → Z step.
C :x: This would only be true if the mutation had no effect, which is explicitly ruled out by the question.
D :x: Enzyme A's activity is not directly linked to enzyme B's activity in a simple linear pathway.  There are no mechanisms suggested for such compensation.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Assuming feedback mechanisms without explicit information: The question doesn't specify feedback loops, so focusing solely on the direct effect of enzyme B inactivation is crucial.
  2.Assuming enzyme A's activity changes: Enzyme A's activity is independent of enzyme B's activity in this simplified pathway.
 **Quick Tips**:
  1.Visualize the metabolic pathway as a linear sequence of reactions.
  2.Consider the immediate consequences of blocking a step in the pathway.

Mr. NARESH KUMAR K · Answer

Increased production of substrate X.

Mr. NARESH KUMAR K · Answer

The correct Option is "Accumulation of intermediate Y and depletion of product Z."

Mr. NARESH KUMAR K · Answer

No change in the concentrations of X, Y, or Z.

Mr. NARESH KUMAR K · Answer

Increased activity of enzyme A to compensate for the loss of enzyme B.

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