Final answer:
Activation of a rod photoreceptor cell by a photon leads to the release of less neurotransmitter into the outer synaptic layer of the retina.
Step-by-step explanation:
When a photon activates a rod photoreceptor cell, it initiates the process of visual transduction in the retina.
Activation of the rod photoreceptor cell results in the activation of a G protein. The G protein then changes the membrane potential of the photoreceptor cell, causing it to release less neurotransmitter into the outer synaptic layer of the retina.