Having a resistance to poison ivy is a dominant characteris?

Question

Having a resistance to poison ivy is a dominant characteristic. What are the possible genotypes if you do a punnett square with one parent who is Homozygous dominant (RR) for being resistant to poison ivy and one parent who is allergic to poison ivy (rr)?

Answer 1

RR x rr

Since the RR parent can only produce gametes with an R allele and the rr parent can only produce gametes with an r allele, then all of their offspring must be Rr and be resistant.