The physical expression of genes are phenotype. Phenotype is the expression of the gene by the appearnace of the organism. It is the characteristics of that trait.
Examples : When pigment is made in our eyes, height ( tall and short) , weight, blond hair is the phenotype for the blond hair genotype and skin colour( black, white ) is the phenotype trait.
Zero degrees latitude is the line designating the Equator and divides the Earth into two equal hemispheres (north and south).
There is no pigment in the brain, so it is in it's natural colour, grey.
