A 45-year-old woman with a vitamin A deficiency is most likely to have increased levels of which of the following substances in rods of the retina?
A)Activated transducin
B)Cyclic guanosine monophosphate
C)Rhodopsin
D)Scotopsin

Question

Quizplus · Accepted Answer

Vitamin A deficiency leads to a decrease in the production of rhodopsin, the light-sensitive pigment found in the rods of the retina. Rhodopsin is composed of opsin (a protein) and retinal (a form of vitamin A). Without adequate vitamin A, the regeneration of rhodopsin is impaired, leading to a decrease in its levels. This results in an increase in cyclic guanosine monophosphate (cGMP) levels because rhodopsin activation normally leads to a decrease in cGMP levels in the phototransduction pathway. Therefore, with less rhodopsin available to be activated, cGMP levels remain elevated.

A 45-Year-Old Woman with a Vitamin a Deficiency Is Most