Spontaneous genetic mutations are one cause of cancer. They can happen at any time for various reasons such as exposure to certain carcinogens. Researchers are working to understand more about their causes. If X is the number of mutations present in a person's body at time Y, then X is a(n) variable.

Urgent in guinea pigs, black fur (b) is dominant over white fur (b). cross a heterozygous (hybrid) black guinea pig with a homozygous (purebred) white guinea pig. complete a punnett square, identify the genotype(s), phenotype(s), and probability (% and fraction) that the offspring will be black and white?