A patient experiences difficulty seeing in dim light (night blindness) but has normal color vision in bright light. This is caused by a dysfunction of the rod cells in the retina.
Using your knowledge of photoreceptors and the diagram below, which statement correctly explains why functional rod cells are highly sensitive to low-intensity light?
Several rod cells share a single connection to one bipolar neurone, resulting in spatial summation of sub-threshold generator potentials.
Each rod cell has a direct 1:11:11:1 connection to a single bipolar neurone, preventing the dilution of neurotransmitter signals.
Rod cells contain iodopsin, a photosensitive pigment that is broken down by very low energy photons.
Rod cells are concentrated within the fovea, where the absence of blood vessels allows maximum light penetration.
