Science (086) — AI-generated practice question

The cornea has a fixed curvature and therefore a fixed focal length — it cannot change its shape. While it performs most of the refraction, it is unable to adjust focus for objects at different distances.

The eye lens, made of fibrous jelly-like material, can change its curvature using the ciliary muscles. When viewing distant objects, the muscles relax and the lens becomes thin (larger focal length). When viewing nearby objects, the muscles contract, the lens becomes thicker (shorter focal length). This adjustment of focal length, called accommodation, allows clear vision at varying distances — something the cornea cannot do alone.

Source: Chapter 10, Section 10.1 and 10.1.1

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• The key distinction examiners want: cornea = fixed refractor; lens = variable focuser.
• Name the mechanism: ciliary muscles change lens curvature → focal length changes → accommodation.
• Mention both cases (distant and near) to earn full marks.
• The word accommodation is a must-use term here.