Question

Given below are two statements.
Statement I - Oxaloacetate is useful as a precursor for synthesis of aspartic acid.
Statement II - $\alpha$-ketoglutarate is useful for synthesis of glutamic acid.
In light of above statements, select the correct answer from the option given below.

• A. Both statement I and statement II are correct.
• B. Both statement I and statement II are incorrect.
• C. Statement I is correct and statement II is incorrect.
• D. Statement I is incorrect and statement II is correct.

Hint:

Memory trick: OAA $\rightarrow$ Aspartate, $\alpha$-KG $\rightarrow$ Glutamate. These are the two most important transamination pairs in exams.

Answer 1

The Correct Option is A

Concept: In plant metabolism, organic acids formed during cellular respiration (Krebs cycle) act as precursors for amino acid synthesis through transamination reactions.
• Transamination: Transfer of an amino group from one compound to a keto acid to form a new amino acid.
• Important keto acids involved:
• Oxaloacetate $\rightarrow$ Aspartic acid
• $\alpha$-ketoglutarate $\rightarrow$ Glutamic acid

Step 1: Analyze Statement I.
Oxaloacetate (a 4-carbon compound of Krebs cycle) accepts an amino group and gets converted into aspartic acid via transamination. Hence, Statement I is correct.

Step 2: Analyze Statement II.
$\alpha$-ketoglutarate (a 5-carbon compound of Krebs cycle) accepts an amino group to form glutamic acid. This is a fundamental reaction in nitrogen metabolism. Hence, Statement II is also correct.

Step 3: Conclusion.
Both statements correctly describe precursor-product relationships in amino acid biosynthesis. Final Answer: Option (A)