Question

Analyse the figure given and answer the following questions.
(a) Identify the figure related to clear vision in dim light.
(b) Which muscular activities take place here?

Hint:

Dim light → pupil dilates → radial muscles contract. Bright light → pupil constricts → circular muscles contract.

Answer 1

Step 1: Understanding the figures.
The given figures (A, B, and C) represent different conditions of the pupil of the human eye under varying light intensities. The size of the pupil changes depending on the amount of light entering the eye.
Step 2: Identifying dim light condition.
In dim light, the pupil becomes large (dilated) to allow more light to enter the eye for better vision. Among the given figures, Figure C shows the largest pupil.
Step 3: Answer for part (a).
Therefore, the figure related to clear vision in dim light is Figure C.
Step 4: Muscular activities involved.
The change in pupil size is controlled by the muscles of the iris:
- Radial muscles contract to dilate the pupil (in dim light).
- Circular muscles relax during this process.
Step 5: Conclusion.
Thus, in dim light, radial muscles contract and circular muscles relax, causing pupil dilation to allow more light inside the eye.