Rods - GCSE Biology Definition

In GCSE Biology, rods are light-sensitive cells in the retina at the back of the eye. They are one of two types of photoreceptors, the other being cones. Rods are especially important for vision in dim light, as they are more sensitive to low light levels than cones. However, rods do not detect colour, which is why we see in shades of grey in the dark. They help us to detect shapes and movement, making them essential for night vision and peripheral vision.