Eye and ear structure and function — A/L Biology

How do I practise Eye and ear structure and function?

1 question with a worked solution

1. In the human eye, what structural changes occur in the ciliary muscle and suspensory ligaments during accommodation for viewing nearby objects?
   1. A) Ciliary muscles contract, suspensory ligaments tighten, lens becomes flatter
   2. B) Ciliary muscles contract, suspensory ligaments relax, lens becomes more convex
   3. C) Ciliary muscles relax, suspensory ligaments relax, lens becomes more convex
   4. D) Ciliary muscles relax, suspensory ligaments tighten, lens becomes flatter
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   Correct answer: B) Ciliary muscles contract, suspensory ligaments relax, lens becomes more convex

   For near vision, the ciliary muscle contracts, reducing tension on the suspensory ligaments (zonules). This allows the elastic crystalline lens to round up and become more convex, increasing its refractive power.

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   Step 1: Accommodation for near objects requires greater convergence (higher optical power). Step 2: Ciliary muscle contracts (sphincter-like movement inward). Step 3: Suspensory ligaments slacken (relax). Step 4: Lens elasticity causes it to become thicker and more spherical/convex. Answer: Ciliary muscles contract, suspensory ligaments relax, lens becomes more convex.
   Modelled on: the A/L Biology examination pattern

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Where does Eye and ear structure and function fit in the syllabus?

Year 2 · Term 1