The vitamin that is a coenzyme in the transfer of one-carbon units is: MCQ with Answer and Explanation

Explanation:
Vitamin B₆ (pyridoxine, pyridoxal, pyridoxamine) is a coenzyme (pyridoxal phosphate, PLP) for many enzymes involved in amino acid metabolism, including transaminases and decarboxylases. B₁ acts in carbohydrate metabolism, B₂ in redox reactions, B₁₂ in methylation and DNA synthesis.

Explanation:
Aldosterone, from the adrenal cortex, acts on the distal tubule and collecting duct to increase sodium reabsorption (and water follows) and potassium secretion, raising blood volume and pressure. ADH increases water reabsorption, ANP reduces sodium reabsorption, renin is an enzyme initiating the RAAS.

Explanation:
Not all bacteria cause disease; many are beneficial (e.g., nitrogen fixers, gut flora). The other statements are true.