1. In some mice, short  tails are dominant to long tails.  If a heterozygous mouse is crossed with a homozygous long tail mouse, what is the probability that the offspring will have long tails?

2. In a flowering plant: blue flowers is (B) is dominant to yellow flowers (b) and tall stems (T) are dominant to short stems (t). What fraction of the progeny of the cross BbTt × BBtt will have blue flowers and shorts stems?

3. A couple has three children, all of whom have blue eyes and brown hair. Both parents are homozygous for blue eyes (BB), but one has brown hair (rr) and the other has black hair (Rr). What is the probability that their next child will be a blue-eyed and have black hair?