The figure given below refers to the vertical section of the eye of a mammal. Study the figure carefully and answer the following questions.
(a) Label the guidelines shown as 1 to 10.
(b) Write one important role of parts shown as 3 and 7.
(c) Write one structural difference between the parts shown as 9 and 10.
(d) Mention one functional difference between the parts shown as 6 and 8.
(a) The guidelines are labelled below:
- 1 → Aqueous chamber
- 2 → Lens
- 3 → Iris
- 4 → Cornea
- 5 → Conjunctiva
- 6 → Sclera
- 7 → Choroid
- 8 → Retina
- 9 → Yellow spot
- 10 → Optic nerve (Blind spot)
(b) Part 3 (Iris) — It contains radial muscles to dilate the pupil and circular muscles to constrict the pupil.
Part 7 (Choroid) — It is the middle layer of the eyeball, richly supplied with blood vessels and provides nourishment to the eye.
(c) Part 9 (yellow spot) contains sensory cells especially the cone cells while part 10 (blind sport) contains no sensory cells.
(d) Part 6 (sclera) gives shape to the eyeball and part 8 (retina) acts as screen to form image of an object.