4. Cross a white bull with a white cow. Show the Punnett Square: % Red Cow
% Roan Cow
% White Cow

100% white cow

Explanation:

This question involves a single gene coding for skin color in cattle. The allele for red color (R) is codominant with the allele for white color (r). Hence, the roan cattle (Rr) will possess both red and white coloration.

According to this question, a white bull (rr) is crossed with a white cow (rr). Each parent will produce the "r" gamete, which when used in a punnet square will produce all WHITE COWS i.e 100% white cows. See punnet square attached.

In homeostasis fashion, cells undergo balanced cell division and programmed cell death (apoptosis) through regulated signalling.This maintains tissue integrity. On the one hand, Proto-oncogenes promotes cells proliferation. On the other hand, tumors suppressors inhibit cell growth and division especially in cells with damaged dna.
Therefore mutations on these oncogenes could result to uncontrolled cell proliferation. Cancer cells also overexpress angiogens that results to proliferation of blood vessels in tumors. This contributes to their metastasis in the body.