Question

Note the relationship between the first two words and suggest as word for the fourth place.

Cones:iodopsin::rods:_______

Answer 1

Rhodopsin

1. Rods and cone are photoreceptor cells present in the retina that enables us to seen in the dim light and bright light respectively.
2. This is possible by the pigments produced by these cells like rhodopsin (rods) and iodopsin (cones).
3. Iodopsin is secreted by cones cells and enables us to detect bright light.
4. Rhodopsin is secreted by rod cells and enables us to detect dim light.

Final answer: Cones:iodopsin::rods: rhodopsin