Cornea in human eye
- (a)is a light sensitive screen.
- (b)is a muscular diaphragm.
- (c)contains blood vessels.
- (d)is composed of proteins and cells.
Correct — D, the cornea is composed of proteins and cells. The cornea is the transparent front layer of the eye, built mainly from regularly arranged collagen (a protein) fibres together with specialised cells, and it has no blood vessels. This orderly protein-and-cell structure is what keeps it clear and lets light enter the eye. So among the options, 'composed of proteins and cells' correctly describes the cornea.
- (a)is a light sensitive screen. — The light-sensitive screen of the eye is the retina, at the back, where images form — not the cornea, which is the clear front window.
- (b)is a muscular diaphragm. — The muscular diaphragm that adjusts the size of the pupil is the iris; the cornea is not muscular.
- (c)contains blood vessels. — The cornea is avascular — it has no blood vessels, getting oxygen and nutrients from tears and the fluid behind it. That is also why donated corneas can be transplanted.
The cornea is the transparent, dome-shaped front surface of the eye. It is chiefly a highly ordered arrangement of collagen protein fibres with a few types of cells (epithelial, stromal and endothelial), and it deliberately has no blood vessels so that it stays clear. It provides most of the eye's fixed focusing power, bending incoming light towards the lens and retina.
Each wrong option names another eye structure's property: light-sensitive screen = retina, muscular diaphragm = iris, and 'contains blood vessels' is true of most tissues but not the cornea. The one true statement about the cornea is that it is made of proteins (collagen) and cells.
- The cornea is the transparent front layer of the eye, made mainly of collagen protein and cells.
- It is avascular (no blood vessels); it gets nutrients from tears and the aqueous humour.
- It provides most of the eye's refracting (focusing) power.
- Because it is avascular and transparent, the cornea is the part used in eye (corneal) donation.
Only the last statement truly describes the cornea — so the answer is (d).
- Confusing the cornea with the retina (the light-sensitive screen) or the iris (the muscular diaphragm).
- Assuming every living tissue has blood vessels — the cornea is deliberately avascular to stay transparent.
Asked as which statement correctly describes the cornea — rule out retina and iris properties and the false 'blood vessels' claim.
In eye donation, which one of the following parts of donor's eye is utilised?
- (a) Iris
- (b) Lens
- (c) Cornea
- (d) Retina
Answer(c) Cornea
Same tissue — the cornea. Only the transparent, avascular cornea is used in eye donation, which is exactly why the card's key facts (proteins-and-cells, no blood vessels) matter.
Light enters the eye through a thin membrane called
- (a) retina
- (b) cornea
- (c) pupil
- (d) iris
Answer(b) cornea
Same structure — the cornea. That 2020 NDA item names the cornea as the thin membrane through which light enters the eye; this one tests what the cornea is made of.
- practice — not a real PYQ
In the human eye, most of the refraction (bending) of light takes place at the
- (a)lens
- (b)cornea
- (c)retina
- (d)iris
Answer(b) cornea — the cornea provides most of the eye's fixed focusing power.
- practice — not a real PYQ
Which part of the eye is used in eye donation?
- (a)Retina
- (b)Iris
- (c)Cornea
- (d)Lens
Answer(c) Cornea — the transparent, avascular cornea can be transplanted.