A person moves from bright light into a dark room. What changes occur in their eyes?
▶️ Answer/Explanation
Ans: C
When moving from bright light to darkness, the pupils dilate (Option C) to allow more light to enter the eyes. This is controlled by the iris muscles. Simultaneously, rod cells (which function better in low light) become more active.
Option A (pupils constrict) occurs in bright light, not darkness. Option B (lens thickens) relates to focusing, not light adaptation. Option D (cornea flattens) is unrelated to light changes.
The diagram shows the structure of the human eye. Which labelled part refracts light entering the eye?
▶️ Answer/Explanation
Ans: D
The lens (D) is the primary structure responsible for refracting light to focus it onto the retina. Along with the cornea, it bends incoming light to ensure a clear image is formed.
Other labelled parts serve different functions: the iris (A) controls pupil size, the retina (B) detects light, and the optic nerve (C) transmits visual signals. Thus, D is the correct answer.