In the ATP-driven proton-potassium exchange mechanism, the H⁺ ions are formed due to dissociation of

Correct option is A

✅ (a) Malic acid [Source of H⁺ in Ion Exchange] • In the ATP-driven H⁺/K⁺ exchange, especially in guard cells and root cells, H⁺ ions are derived from dissociation of malic acid. • Malic acid → malate⁻ + H⁺ • H⁺ ions help in establishing proton gradients and facilitate ion transport across membranes. • Malate also acts as a counter-anion for cation uptake.
❌ (b) Phosphoglycolic acid • Intermediate in photorespiration. • Does not play a major role in proton exchange or H⁺ ion generation.
❌ (c) Oxaloacetic acid • Part of the TCA cycle and C4 pathway, but not the primary proton donor in ion exchange.
❌ (d) Pyruvic acid • Key glycolytic product, but not directly involved in generating H⁺ for ATP-driven ion pumps.