YKS 2022 · Soru 79

(I) The retina, the screen at the back of the eye on which the lens of the eye casts its image, contains two different kinds of sensitive elements. (II) One set, the rods, register shape; the other, the cones, register colour. (III) Animals that sleep at night and are active mostly during the daylight hours have a mixture of both of these in their retinas. (IV) Some species are able to see over an even wider colour spectrum than we can. (V) But colour is largely invisible at night so nocturnal creatures have eyes with retinas packed almost entirely with rods.