Macula lutea is present in.

Which of the following statements are correct for the iris?
$(I)$. The ciliary body extends forward to form the iris.
$(II)$. It is a pigmented and opaque structure.
$(III)$. It is the visible coloured portion of the eye.
Choose the correct option.

Distinguish between:
$(1)$ Receptor proteins and Receptor cells.
$(2)$ Aqueous humor and Vitreous humor.

The density of the vitreous humour is approximately equal to that of the:

Which of the following is not correct for rods?
$(I)$. Twilight vision is the function of the rods
$(II)$. It is responsible for daylight vision sometimes
$(III)$. The rods contain a protein called rhodopsin
$(IV)$. Rods are photoreceptor cells
Choose the correct option

The coloured (pigmented) layer of the eye is: