Which pigment is responsible for night vision?

• A. Chlorophyll a
• B. Rhodopsin
• C. Carotene
• D. Phycoerythrin

Answer: (B)

Verified step by step guidance

1. Understand the context of the question: Night vision refers to the ability of organisms to see in low-light conditions. This is facilitated by specialized pigments in the photoreceptor cells of the retina.
2. Review the function of each pigment option provided: Chlorophyll a is a photosynthetic pigment found in plants, algae, and cyanobacteria, and is unrelated to vision. Carotene is a pigment involved in photosynthesis and also serves as a precursor to vitamin A, which is important for vision but not directly responsible for night vision. Phycoerythrin is a pigment found in red algae and cyanobacteria, used for capturing light energy in photosynthesis.
3. Focus on rhodopsin: Rhodopsin is a light-sensitive pigment found in the rod cells of the retina. Rod cells are specialized for low-light (scotopic) vision, making rhodopsin the pigment responsible for night vision.
4. Understand the mechanism: Rhodopsin is composed of a protein called opsin and a light-absorbing molecule called retinal (derived from vitamin A). When light hits rhodopsin, it undergoes a conformational change, triggering a signal transduction pathway that allows the brain to perceive light in dim conditions.
5. Conclude: Based on the information, rhodopsin is the correct answer as it is directly involved in enabling night vision, unlike the other pigments listed.