Answer:
The sex chromosomes (X and Y) determine whether a cat will be male or female. Each cat has a pair of sex chromosomes with the possible combinations of XX (female) and XY (male). The X chromosome also carries the coding gene for the black and orange colors in a calico's coat.
Step-by-step explanation:
Female calico cats have two X chromosomes and therefore have two chromosomes with color code. Only if the cat gets one orange-coded X and one black-coded X, will she be calico, expressing both black and orange coloration.
Because male cats have one X chromosome with code for black or orange and one Y chromosome with no color genes, they cannot technically be calico. They'll only express either black or orange, but not both.