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

Question

Which step in the Krebs cycle does NOT involve an oxidation reaction?

Mr. NARESH KUMAR K · Accepted Answer

## CORE INFORMATION
✓ **Answer**: A
## CONCEPT FRAMEWORK
 **Primary Concept**: Krebs Cycle Reactions
 **Related Topics**: Oxidation-reduction reactions, metabolic pathways
 **Prerequisites**: Understanding of redox reactions and the steps of the Krebs cycle.
## SOLUTION PATHWAY
**Given Information**:
The question asks to identify the step in the Krebs cycle that does not involve oxidation.
**Method & Steps**:
1. Analyze each step in the Krebs cycle provided in the options:
    A. Succinyl-CoA to succinate: This step involves substrate-level phosphorylation, where a phosphate group is transferred to GDP to form GTP, but no oxidation occurs.
    B. Isocitrate to α-ketoglutarate: This is an oxidative decarboxylation reaction, involving the loss of CO2 and the reduction of NAD+ to NADH.
    C. α-ketoglutarate to succinyl-CoA: This is also an oxidative decarboxylation reaction, involving the loss of CO2 and the reduction of NAD+ to NADH.
    D. Malate to oxaloacetate: This is an oxidation reaction, where NAD+ is reduced to NADH.
2. Identify the step without oxidation:
    Only the conversion of succinyl-CoA to succinate does not involve an oxidation reaction.
3. Conclusion:
    The correct answer is A. Succinyl-CoA to succinate.
## OPTION ANALYSIS
A ✓: This step involves substrate-level phosphorylation, a transfer of a phosphate group, not a redox reaction.  No electrons are transferred.
B :x: Isocitrate to α-ketoglutarate involves oxidation and decarboxylation.
 C :x: α-ketoglutarate to succinyl-CoA involves oxidation and decarboxylation.
D :x: Malate to oxaloacetate is an oxidation reaction.
## LEARNING AIDS
 **Common Mistakes**: Confusing substrate-level phosphorylation with oxidation.
 **Quick Tips**: Remember that oxidation involves the loss of electrons, while substrate-level phosphorylation involves the transfer of a phosphate group.

Mr. NARESH KUMAR K · Answer

The correct Option is "Succinyl-CoA to succinate"

Mr. NARESH KUMAR K · Answer

Isocitrate to α-ketoglutarate

Mr. NARESH KUMAR K · Answer

α-ketoglutarate to succinyl-CoA

Mr. NARESH KUMAR K · Answer

Malate to oxaloacetate

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