The lens of the eye and the retina are developed from which embryonic germ layer?

Answer briefly:
$(a)$ How do you perceive the colour of an object?
$(b)$ Which part of our body helps us in maintaining the body balance?
$(c)$ How does the eye regulate the amount of light that falls on the retina?

The 'adaptation' of eyes in the dark is due to

Analogy type question:
$(1)$ Photoreceptor cells : Cones : Dim light vision : ........
$(2)$ Eyeball contains transparent crystalline : Lens : : In front of the lens : .........

Macula lutea is present in.

Rods contain visual purple or rhodopsin. When light falls on rhodopsin,it is