is important to the transmission of nerve impulses.
a) Zinc
b) Calcium
c) Sodium
d) Iron

The role of the retina is to receive light that the lens has focused. It then converts the light into neural signals which get sent to the brain for visual recognition.
Internal Regulators allow the cell cycle to proceed only when certain processes have happened inside the cell.
Evolution is not a random process. The genetic variation
on which natural selection acts may occur randomly, butnatural selection itself is not random at all.