a special pigment found in the rods and cones of the retina
photopigment 例句
英汉例句
It's plausible that millions of years ago a single mutation resulted in two different versions of the photopigment gene becoming located on the same X chromosome.
But was an extra photopigment all that was needed to evolve trichromatic vision? Or does seeing the world in all its colourful splendour require extra brain power too?