In which case do you need to allow more light to enter the eye, when the light is dim or bright? Explain the arrangement in the eye to allow only the required amount of light depending on the situation. [3 MARKS]

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Solution

Each point: 1 Mark

1. When the light is dim, more light is required to enter the eye. This is taken care by the opening in the eye called pupil.
2. The size of pupil is controlled by dark muscular structure called iris.When light is bright, iris decreases the size of pupil so that less light enters it.
3. When the light is dim, iris increases the size of pupil so that sufficient light enters into the eye.

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