Biological Systems MCAT Practice Exam

Which cells are best at detecting low light conditions?

1. Cones

2. Bipolar cells

3. Rods

4. Ganglion cells

The correct answer is: Rods

Rods are specialized photoreceptor cells in the retina that are highly sensitive to low light levels. They are primarily responsible for vision in dim lighting conditions, which makes them essential for night vision. Rods contain a photopigment called rhodopsin, which is extremely sensitive to light and allows them to respond to a single photon. This high sensitivity enables rods to function in low-light environments, where they can detect light and contribute to peripheral vision. In contrast, cones are photoreceptor cells that are responsible for color vision and function best in bright light conditions. Bipolar cells and ganglion cells are part of the neural circuitry of the retina but do not directly detect light. Instead, they process the signals from rods and cones before transmitting information to the brain. Therefore, rods are the most effective cells for detecting low light conditions among the choices provided.