Name:
Class Block:
Among star bellied sneetches, the alleles for starred bellies (S) and for tasseled tops (T) are dominant over the
alleles for plain bellies (s) and smooth tops (t).
1. What are the possible genotypes for sneetches whose phenotypes are:
(a) star belly, tassled top
(b) star belly, smooth top
(c) plain belly, tassled top
(d) plain belly, smooth top
2. Sneetches, despite occasional outbreaks of discord between those of different phenotypes, are very
progressive thinkers, and frequently choose mates irrespective of phenotype. The following problems
are based on a female of the genotype SsTt and a male of the genotype sstt who wish to start a family.
(a) What is the phenotype of the female?
(b) What is the phenotype of the male?
(c) What are the possible genotypes and phenotypes of all of their possible offspring? (show the Punnett
square)
(d) Unlike biology students, sneetches lack a basic understanding of genetics. You are a genetic counselor
and the prospective parents come to you for advice. What is the probability that their new child will
have the same genotype as his/her mother?
(e) What is the probability that the little one will look like dad?
(f) Zooming into the future, mother and father sneetch are ready for child number 2. Number 1 had the
same genotype as dad, so they assume that number 2 will have mom’s genotype. Is their assumption
correct? Why or why not?