The genes that specify where and when photoreceptors arise during embryonic development are shared among flatworms, annelids, arthropods, and vertebrates. What can we conclude from this observation?
A) Members of these four groups are more closely related to each other than to other groups.
B) What humans see is very similar to the images seen by flatworms, annelids, and arthropods.
C) The genetic underpinnings of all photoreceptors were present in the earliest bilaterian animals.
D) A single-lens eye has been favored throughout most of animal evolution.

Question

Quizplus · Accepted Answer

The shared genes across diverse groups suggest that the genetic basis for photoreceptors was already present in the common ancestor of these groups, indicating an early origin in bilaterian animals.

The Genes That Specify Where and When Photoreceptors Arise During