What is substrate-level phosphorylation?
a. Phosphorylation of ATP coupled to an ion gradient
b. ATP and AMP synthesis from two molecules of ADP
c. Phosphorylation of AMP by ATP
c. Phosphorylation of glycolytic intermediates
d. ATP synthesis when the phosphate donor is a substrate with high phosphoryl transfer potential

D --  ATP synthesis when the phosphate donor is a substrate with high phosphoryl transfer potential

Explanation:

Substrate- level phosphorylation is the synthesis of ATP from ADP by the transfer of phosphoryl group from a substrate with high phosphoryl group potential to the ADP molecule.

In substrate-level phosphorylation, the donor is a phosphorylated intermediate molecule with a high phosphate transfer potential and it is a way through which phosphate in introduced into a molecule, the other two ways are oxidative phosphorylation and photophosphorylation. In substrate-level phosphorylation, a PO4^2- is transferred from a phosphate intermediate (substrate) to ADP to form ATP. Phosphorylase and kinases are enzymes involved in this reaction. An example is the reaction in glycolysis which involves phosphoenolpyruvate and ADP to form Pyruvate and ATP. This is to ensure adequate supply of energy to cells and also during anoxia so as not to make mitochodria strain the glycolytic ATP reserves.

d. groundwater flows through the subsoil and deposits minerals.