JAMB Biology 2025 Objective — Question 20
Question 20 of 40 from the Joint Admissions and Matriculation Board (JAMB) Biology 2025 Objective paper, with the correct answer and a full explanation.
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In the human eye, which structure controls the amount of light entering by adjusting the size of the pupil?
- A. Lens
- B. Retina
- C. IrisCorrect
- D. Cornea
Explanation
The iris controls the size of the pupil by contracting or relaxing the muscles in response to the amount of light in the environment. In bright light, the iris constricts the pupil to reduce light entry, while in dim light, it dilates the pupil to allow more light in.
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