Kaplan Nursing Entrance Practice Exam

What type of photoreceptors are cones responsible for?

1. Responding to low-intensity light

2. Detecting motion in bright light

3. Responding to high-intensity illumination and color

4. Operating in nighttime conditions without color

The correct answer is: Responding to high-intensity illumination and color

Cones are a type of photoreceptor in the retina that are primarily responsible for color vision and function best under bright light conditions. They are sensitive to high-intensity illumination, which allows them to detect a broad range of colors, thanks to the three different types of cones that respond to different wavelengths of light: short (blue), medium (green), and long (red) wavelengths. This ability enables the perception of colors in various environments, particularly during daylight. The other choices do not accurately describe the function of cones. For instance, cones do not respond well to low-intensity light; instead, rod photoreceptors play that role. Additionally, while cones can assist in detecting shapes and details in bright light, they are not specialized for motion detection, which is more closely related to the function of rods in low-light conditions. Lastly, cones do not operate effectively in nighttime conditions, where rod photoreceptors are more dominant and are responsible for vision in low-light settings, including black-and-white vision without color. Thus, the correct identification of cones with their capacity to respond to high-intensity illumination and color solidifies their essential role in daytime and vibrant vision.