USA Biology Olympiad (USABO) Practice Exam

Rods and cones in the eye are associated with what types of vision, respectively?

1. Color...light/dark

2. Light/dark...color

3. Peripheral...central

4. Color...motion

The correct answer is: Light/dark...color

Rods and cones are two types of photoreceptor cells in the retina of the eye, each serving a distinct role in vision. Rods are primarily responsible for vision in low light conditions, providing our ability to see in dimly lit environments, which is often referred to as scotopic or light/dark vision. This capability allows us to detect various shades of gray and movements but not colors. Cones, on the other hand, are specialized for daylight vision and color discrimination. They enable photopic vision, which allows us to perceive a range of colors in well-lit conditions. There are three types of cones, each sensitive to different wavelengths of light corresponding to blue, green, and red. Thus, cones enable us to experience rich color vision. This understanding of the functions of rods and cones supports the conclusion that rods are associated with light/dark vision, while cones are responsible for color vision. Thus, the correct pairing of these functions is represented in the option indicating that rods are associated with light/dark vision, and cones are associated with color vision.