Each cell in your body contains .............. pairs of chromosomes.

One pair, the ..................................., determines gender. The

Because females have

two X chromosomes and males have only one, body cells

randomly turn off one of the X chromosomes. This is called

...........................................................

Black patches are formed when an

X chromosome carrying the allele for orange coat color

is turned off.

Orange patches are formed

when an X chromosome carrying the allele for black coat

color is turned off.