Answer: A keto acid.
- A A fatty acid
- B A nucleic acid
- C A simple sugar
- D A keto acid
Correct answer: D. A keto acid
Explanation: Transamination moves an amino group from one amino acid onto a keto acid, forming a new amino acid.
Atmospheric N₂ is fixed into ammonia by nitrogen-fixing bacteria (protected from oxygen by leghaemoglobin in root nodules), converted to nitrate via nitrification for plant uptake, and eventually returned to the atmosphere as N₂ via denitrification, completing the cycle.
Concept context
Essential mineral elements, their roles and deficiency symptoms. Nitrogen fixation and soil nutrition.