You are working on a mouse model for deafness and have established a homozygous strain of mice that cannot hear. You call this mouse strain #1and have determined that the phenotype is caused by a recessive allele in a single gene. You learn that a colleague has isolated another homozygous strain of mice that is called strain #2, which is also deaf because of a recessive allele in a single gene. Finally, a third colleague has isolated a homozygous strain of mice that are deaf. The phenotype associated with strain #3is also caused by a recessive allele in a single gene.
1. You cross a true-breeding strain #1 mouse to a true-breeding strain #2 mouse and find that the F1 progeny can hear. In another experiment, you cross a true-breeding strain #1 mouse to a true-breeding strain #3 mouse and find that all of the F1 p progeny are deaf. Based on these data, what do you predict the phenotype of the F1 progeny will be when you cross a true-breeding strain #2 mouse to a true- breeding strain #3 mouse?
A. 50% of the mice will be deaf .
B. 100% of the mice will be deaf .
C. None of the mice will be deaf .
2. You cross a strain #1 mouse to a strain #2 mouse and get F1 progeny. If you cross the F1 progeny together, what fraction of mice do you predict will be deaf in the F2 generation?
A. 9/16
B. 3/16
C. 7/16
D. 4/16
E. 1//16