Science (086) — CBSE Class 10 board question

(a)
(i) Retina: It contains light-sensitive cells (rods and cones) that convert light into electrical signals, which are sent to the brain via the optic nerve, enabling vision.

(ii) Pupil: It controls the amount of light entering the eye by changing its size — it dilates in dim light and constricts in bright light.

(b) Ciliary muscles are attached to the eye lens. When viewing a nearby object, ciliary muscles contract, making the lens thicker (more convex) to increase its converging power. When viewing a distant object, the muscles relax, making the lens thinner (less convex) to decrease converging power. This adjustment of focal length is called accommodation.

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• The question is from the chapter "The Human Eye and the Colourful World" (Ch. 11, Science Class 10).
• For part (a), name the specific function — don't just say "it helps in vision."
• For part (b), the key terms examiners look for are: contract/relax, thicker/thinner lens, and accommodation. Always link muscle action to lens shape change to focal length change.
• The source passages provided were from unrelated chapters, but this answer is based on the NCERT Class 10 Science Ch. 11 content as prescribed.