1) if photo receptors don't generate action potentials, does the optic nerve generate one? is there a list of neurons to know that do generate action potentials or do most of them do?


For my MCAT personally, I didn't really have a list of neurons that generate action potentials - most of the times if there is an unusual exception it is going to be introduced in the particular passage.

As for the photoreceptors, it's not that they don't generate action potentials, its that they are constantly generating them until they receive stimuli, and once that happens they "turn off" production of neurotransmitters and thus deactivate the neurons associating with them.

I'm not sure exactly how this relates to the brain, but my assumption is that the brain registers that a green cone is "knocked out" temporarily and then processes that the thing that "knocked out" these receptors must be green.

This is contrasting the paradigm that a cone that would turn on when it sees something green.

2) if rods are only perceiving black and white then why does it involve the entire visible spectra if it can't perceive colour?

Recall you have two different types of photoreceptors, rods which see better in low light, but do not see colour, and cones which see better in bright light, but can also perceive colour. Your cones are the reason why we can perceive colour.

Please let me know if this is unclear.