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

Question

Which of the following is NOT a direct product of the Krebs cycle?

Mr. NARESH KUMAR K · Accepted Answer

## CORE INFORMATION
✓ **Answer**: C
## CONCEPT FRAMEWORK
 **Primary Concept**: Krebs Cycle (Citric Acid Cycle) Products
 **Related Topics**: Cellular Respiration, Metabolism, ATP Production
 **Prerequisites**: Understanding of the Krebs cycle reactions and the role of its intermediates.
## SOLUTION PATHWAY
**Given Information**:
The question asks to identify a molecule that is NOT a direct product of the Krebs cycle.
**Method & Steps**:
1. Identify the direct products of the Krebs cycle.
  Reasoning: The Krebs cycle is a series of chemical reactions that oxidize acetyl-CoA to produce energy-carrying molecules (ATP, NADH, and FADH2) and carbon dioxide ($CO_2$).
  Formula/Rule:  The overall reaction of the Krebs cycle can be summarized as:
  Acetyl-CoA + 3 NAD$^+$ + FAD + GDP + $P_i$ + 2 $H_2O$ $\longrightarrow$ 2 $CO_2$ + 3 NADH + 3 $H^+$ + FADH$_2$ + GTP + CoA
 2. Analyze the given options.
  Working: Let's examine each option:
  a) FADH2:  A direct product of the Krebs cycle (succinate dehydrogenase step).
  b) NADH: A direct product of the Krebs cycle (multiple steps).
  c) ATP synthase: This enzyme is responsible for ATP synthesis during oxidative phosphorylation, which occurs *after* the Krebs cycle. It's not a direct product of the Krebs cycle itself.  Although GTP is produced in the cycle, ATP synthase is not.
  d) CO2: A direct product of the Krebs cycle (two molecules per cycle).
 3. Determine the correct answer.
  Result: ATP synthase is not a direct product of the Krebs cycle.
  Verification: The Krebs cycle produces reducing equivalents (NADH and FADH2), which are then used in oxidative phosphorylation (electron transport chain) to generate ATP via ATP synthase.  The cycle itself directly produces GTP, which can be converted to ATP, but not ATP synthase.
 ## OPTION ANALYSIS
A :x: FADH2 is a direct product.
B :x: NADH is a direct product.
C ✓: ATP synthase is not a direct product; it is an enzyme used in oxidative phosphorylation.
D :x: CO2 is a direct product.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Confusing the products of the Krebs cycle with the products of oxidative phosphorylation: Remember that the Krebs cycle produces reducing equivalents that are then used in oxidative phosphorylation to generate ATP.
  2. Overlooking the indirect role of GTP: While GTP is produced, it is ATP synthase that is responsible for the majority of ATP synthesis, and that is not a direct product.
 **Quick Tips**:
  1.Memorize the direct products of the Krebs cycle: NADH, FADH2, CO2, and GTP.
  2.Understand the flow of energy from the Krebs cycle to oxidative phosphorylation.

Mr. NARESH KUMAR K · Answer

FADH2

Mr. NARESH KUMAR K · Answer

NADH

Mr. NARESH KUMAR K · Answer

The correct Option is "ATP synthase"

Mr. NARESH KUMAR K · Answer

CO2

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