Final answer:
Rod cells are OFF in the presence of light due to hyperpolarization and ON in the absence of light when they depolarize. Rod cells detect shades of gray and are involved in low-light level vision, while cones are for color vision in bright light.
Step-by-step explanation:
Rod cells in the human retina are OFF in the presence of light and ON in the absence of light. To understand this, it is important to know that rod cells contain a photopigment called rhodopsin. When light strikes rod cells, it triggers a structural change in rhodopsin, leading to a series of biochemical events that result in the hyperpolarization of the rod cell, thereby turning it 'OFF'. In the absence of light, rod cells depolarize, effectively turning 'ON' and signaling the detection of low light levels.
From the statements provided, the false one about the human eye is "Rods detect color, while cones detect only shades of gray." The correct information is that rods are responsible for vision in low-light conditions and can only detect shades of gray, whereas cones are responsible for color vision and operate in higher light conditions.