Tay-Sachs disease is caused by an allele for a recessive trait. A DNA test on blood can determine if a healthy individual is homozygous or heterozygous. One member of a particular couple is homozygous dominant, and the other member is heterozygous. Refer to the information above. What is the probability that this couple will have a child with Tay-Sachs disease

Zero (0)

Explanation:

Let the allele for Tay-Sachs disease be t.

Homozygous dominant = TT

Heterozygous dominant = Tt

Since the disease is caused by recessive allele, both TT and Tt are normal and free from the disease, although Tt is a carrier.

Crossing the two:

TT   x   Tt  = TT, Tt, TT and Tt

50% of the offspring have TT genotype while the remaining 50% have Tt genotype. Both TT and Tt are normal.

Hence, the probability that this couple will have a child with Tay-Sachs disease is 0.

b c a d mark me

correct answer is a. and d.