Reference no: EM1384160

A couple is about to have a child.  They are concerned about the child because of two traits caused by genes on the SAME chromosome: Tay Sachs, an autosomal recessive neurodegenerative disease, and Polydactyly, a dominant extra finger trait.  The two genes are 20 map units apart.  The mother has Tay Sachs but does not have polydactyly.  The father is a carrier of Tay Sachs, and has polydactyly (he is heterozygous): the two dominant alleles for these phenotypes are on one chromosome, and the two recessive on the other.    

Question 1 -  What is the chance the child will be *phenotypically* normal, expressing neither of these traits?

A.) 5 %

B.) 6.25 %

C.) 10 %

D.) 12.5 %

E.) 20 %

F.) 25 %

G.) 50 %

Question 2 - What is the chance that the child will be a carrier for Tay Sachs?

 

A.) 5 %

B.) 6.25 %

C.) 10 %

D.) 12.5 %

E.) 20 %

F.) 25 %

G.) 50 %