Cholecalciferol is hydroxylated twice to form ____ that acts like a ____ to regulate ____ and ____ metabolism.
A) 24,25-hydroxyvitamin D; vitamin D-binding protein; calcium; chloride
B) ergosterol; vitamin D-binding protein; sodium; calcium
C) 7-dehydrocholesterol; hormone; calcium; phosphate
D) 1,25-dihydroxycolecarciferol; prehormone; sodium; phosphate
E) 1,25-dihydroxycolecarciferol; hormone; calcium; phosphate

Question

Quizplus · Accepted Answer

Cholecalciferol is hydroxylated twice to form 1,25-dihydroxycholecalciferol, which acts like a hormone to regulate calcium and phosphate metabolism. Choice A is incorrect because 24,25-hydroxyvitamin D is not the active form of vitamin D and regulates bone turnover, not calcium and chloride metabolism. Choice B is incorrect because ergosterol is not related to the formation of vitamin D. Choice C is incorrect because 7-dehydrocholesterol is a precursor of cholecalciferol, but not the active form of vitamin D. Choice D is incorrect because 1,25-dihydroxycolecarciferol is misspelled and sodium is not regulated by vitamin D.

Cholecalciferol Is Hydroxylated Twice to Form ____ That Acts Like