Question

Iris is a part of
A. Sclerotic
B. Choroid/ Uvea
C. Choroid and retina
D. Sclerotic and choroid

Answer 1

Hint: Our paired eyes are located in the sockets of the skull known as orbits.
Iris: It is the colored part of the eye which helps regulate the amount of light entering the eye.
When there is bright light, the iris closes the pupil.
And when there is low light, the iris opens up the pupil.

Complete answer:
Adult human eyeballs are spherical in shape.
The wall of the eyeball is composed of three layers.
External layer is composed of a dense connective tissue which is known as sclera.
The anterior portion of this layer is known as cornea.
The middle layer is choroid which contains many blood vessels and looks bluish in color.
This layer is thin over the two-third of the eye balls and becomes thick in the anterior part to form the ciliary body.
The ciliary body continues to form a pigmented and opaque structure known as iris.
Iris: It is the visible colored portion of the eye.
Lens is a transparent crystalline structure which is held in place by ligaments attached to the ciliary body.
Pupil is the apparatus surrounded by the iris.
The diameter of the pupil is controlled by muscle fibres of iris.
The inner layer is retina and it contains three layers of cells
1. Ganglion cells
2. Bipolar cells
3. Photoreceptor cells
So, according to the question, iris is a part of Sclerotic and choroid.

So, the correct option is option D. Sclerotic and choroid.

Note: Mechanism of vision:
Light rays in a visible wavelength focused on the retina.
The photosensitive pigment namely opsin is structurally changed by the light rays from the retinal which further results in changing the membrane permeability.
This produces an action potential in ganglion through bipolar cells.
Then, these action potentials are transmitted by optica nerves to the visual cortex and impulse in analysis and image is formed.