Final answer:
Rod cells have a bad visual acuity compared to cones because multiple rods are connected to a single RGC, leading to less detailed visual information. Rods are adapted for sensitivity over acuity, providing peripheral vision and motion detection in low light, with no color discernment.
Step-by-step explanation:
Rod cells have a lower visual acuity because they are highly sensitive to light and are responsible for vision in very dark conditions. Rods are numerous in the human retina but do not provide the sharpness of vision that cone cells do.
This is partly because many rods converge onto a single retinal ganglion cell (RGC) through bipolar cells, with ratios up to 50:1, meaning the signal from multiple rods must be integrated, which reduces detail and clarity. In contrast, at the fovea, where we have the sharpest vision, each cone is connected to a single RGC, allowing for more detailed visual processing.
Moreover, rods lack the ability to detect color and have higher sensitivity to light, which makes them invaluable for peripheral vision and motion detection, particularly in low light or during night time. As a result, when the environment is poorly lit, and cones cannot function optimally, rods enable us to see, although with less detail and no color.