Multiple choice Which of the following lipids is a biological precursor to vitamin D2? Cholesterol Phytosterols Ergosterol Hopanoids Reveal answer Fill a bubble to check yourself C Correct answer Explanation Ergosterol is a biological precursor (a provitamin) to vitamin D2. It is turned into viosterol by ultraviolet light, and is then converted into ergocalciferol, which is a form of vitamin D.