Which part of the human eye controls the amount of light entering it?
Difficulty: Medium
About this MCQ
This Medium Everyday Science question asks: Which part of the human eye controls the amount of light entering it? The correct choice is C. Iris. Read the options below, commit to one, then use the explanation to see why that choice holds and why the others do not.
Everyday Science items like this one are written for Pakistan exams such as CSS, FPSC, PPSC, and NTS. The difficulty label is a hint about how much of the topic the stem assumes, not a score. Tags and exam names, when they are present, tell you where else the same idea is tested. Previous and next links stay in Everyday Science so you can continue the subject. Related questions point at nearby stems if you want another angle on the same idea.
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- A. Retina
Why not A: The retina detects light and forms images; it does not control light entry.
- B. Cornea
Why not B: The cornea helps focus light but does not regulate its amount.
- C. Iris ✓
- D. Lens
Why not D: The lens focuses light onto the retina by changing shape.
Correct answer
C. Iris
Explanation
Iris is the term that matches “Which part of the human eye controls the amount of light entering it” (option C). Option A (Retina) is wrong: The retina detects light and forms images; it does not control light entry. Option B (Cornea) is wrong: The cornea helps focus light but does not regulate its amount. Option D (Lens) is wrong: The lens focuses light onto the retina by changing shape. Keep Iris as the Everyday Science fact for this stem.
Source: Human anatomy — eye structure
Tags: Biology, Human Body
Relevant exams: PPSC Lecturer
Submitted by: MCQsHub Editorial
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