Which of the following parts of the eye contains light sensitive cells?

Step 1: Analyze the question The question asks which part of the eye contains light-sensitive cells, meaning the cells that detect light and start the process of vision.

Step 2: Explain the concept The eye has several parts, each with its own job:

• Choroid: a dark, blood-vessel-rich layer between the sclera and the retina. It supplies nutrients and oxygen, and its pigment absorbs stray light to prevent internal reflection.
• Iris: the coloured muscular ring that controls the size of the pupil, and so how much light enters the eye.
• Retina: the innermost layer at the back of the eye. It contains the photoreceptor cells, which are light-sensitive. • Rods work in dim light and detect black, white, and shades of grey. • Cones work in bright light and detect colour.
• Lens: a transparent, flexible structure that focuses light onto the retina (accommodation).

Step 3: Solve

• Choroid: nourishes and absorbs light, but does not detect it. ✗
• Iris: controls the amount of light entering. ✗
• Retina: contains rods and cones, which detect light. ✓
• Lens: only focuses light. ✗

Step 4: Answer The retina contains the light-sensitive cells (rods and cones).

Step 5: Exam tip Link each part to its job:

• Iris = Intensity control (regulates the amount of light)
• Lens = Layers of focus (focuses light)
• Choroid = Colour (dark pigment) and Circulation (blood supply)
• Retina = Receptors (rods and cones), where the image is formed

Whenever you see "light-sensitive" in an eye question, think retina.