The diagram illustrates a transverse section of a human eye. (a) Identify the label matching each function: $\quad[3]$ (ii) sends impulses to the brain

III Optic nerve sends the signals to brain. When the retina sends neural impulses representing an image to the brain, it spatially encodes (compresses) those impulses to fit the limited capacity of the optic nerve. Compression is necessary because there are 100 times more photoreceptor cells than ganglion cells. This is done by "decorrelation", which is carried out by the "centre–surround structures", which are implemented by the bipolar and ganglion cells. There are two types of centre–surround structures in the retina – on-centres and off-centres. On-centres have a positively weighted centre and a negatively weighted surround. Off-centres are just the opposite. Positive weighting is more commonly known as excitatory, and negative weighting as inhibitory.

The diagram given is a cross-section of the human eye. Give the functions of the parts labelled 1, 3, 6.

The parts that are labelled1, 3, and 6 are vitreous humor, pupil, and blindspot, respectively, in the eye of a human. Vitreous humor: This maintains the spherical shape of the human eyes. Pupil: It regulates the amount of entry of light in the eyes. Blindspot: This is the place where all the blood vessels and optic nerves leave the eyeballs.