Question

DQ 1 How does Rods and cones differ functionally?

DQ 2 Name the structures of the eyeball in a chronological order the light ray will pass through.

Answer 1

DQ 1 How does Rods and cones differ functionally?

Answer:

There are two types of photoreceptors in the human retina, rods and cones.

• Rods have rod-like structure and provide low light vision and night vision (scotopic vision).
• Cones are of the cone shape, fewer in number and provides the vision in the day or bright lights (photopic vision).
• Rods contain rhodopsin pigment rich in Vitamin A responsible for night vision and cones contain iodopsin pigment (violet pigment).
• Cones provide Colour vision, which is of three types: red, blue and green, whereas rods cells do not give Colour vision, they do not have any differentiation.
• Lack of the rhodopsin in the rods may cause night blindness, while lack of the iodopsin in the cones may cause Colour blindness.
• Rods are responsible for low spatial acuity whereas cones are responsible for high spatial acuity.
• Rods cells are sensitive to both scattered and direct light whereas cones cells are sensitive only to direct light.

DQ 2 Name the structures of the eyeball in a chronological order the light ray will pass through.

Answer:

Structures of the eyeball in a chronological order the light ray will pass through are

• Cornea : a protective clear covering over the pupil and iris.
• Iris: the circular, colored area of the eye that surrounds the pupil.
• Pupil : the dark circle in the center of the iris, which is the colored portion of the eye.
• Lens : a clear, flexible structure that focuses an upside-down image onto the retina.
• Vitreous humor : a clear, jelly-like substance that fills the center of the eye.
• Retina : a layer of light-sensitive cells at the back of the eye. It is made up of two kinds of photoreceptor cells: cones and rods.
• Optic nerve
• Visual cortex
• ​​​

Diagram