During glycolysis, dehydrogenase enzymes catalyse the A removal of hydrogen ions from NADH₂ B removal of hydrogen ions from citrate C transfer of hydrogen ions to glucose D transfer of hydrogen ions to NAD. - Scottish Highers Human Biology - Question 5 - 2016

The correct option is D. During glycolysis, dehydrogenase enzymes play a crucial role in the oxidation of substrates. These enzymes facilitate the transfer of hydrogen ions (protons) to NAD⁺, reducing it to NADH. This process is vital as NADH serves as an important electron carrier within the cell, allowing for further energy production through cellular respiration.