The combination that would produce a 1:2:1 ratio of genotypes and a 3:1 ratio of phenotypes in the offspring is III. Heterozygous x Heterozygous, also specifically listed as IV. Aa x Aa. This cross involves parents with Aa genotypes for a given trait where A is the dominant allele and a is the recessive allele. Golden Retriever, Labrador Retriever, German Shepard, Bichon, Poodle, Shih Tzu, etc. An example of a hybrid breed or designer dog would be a labradoodle, goldendoodle, malti-poo, puggle. Those. These represent all the combinations of the alleles that can result from this genetic cross. To summarize, crossing two mice that are heterozygous for both traits will yield a variety of genotypes in their offspring, which can be predicted accurately using a Punnett square. According to Mendelian genetics, a heterozygous organism will have one dominant and one recessive allele which is represented as 'Gg', making it the correct definition of a heterozygous dominant genotype. The definitions of heterozygous and homozygous genotypes are well-established in genetics. Sources like textbooks on Mendelian genetics and online educational platforms provide detailed explanations of these concepts. The genotypes SS, Ss, and ss correspond to homozygous dominant, heterozygous, and homozygous recessive, respectively. Homozygous dominant has two dominant alleles, heterozygous has one of each, and homozygous recessive has two recessive alleles. These classifications help in understanding how traits are inherited and expressed in organisms. To identify which of the given genotypes is heterozygous, we first need to understand the definitions of heterozygous and homozygous genotypes. Homozygous: A genotype is described as homozygous when an individual has two identical alleles for a gene. For example, an individual could have two dominant alleles (AA) or two recessive alleles (bb). To determine which of the provided genotypes are heterozygous, we first need to understand what a heterozygous genotype is. A heterozygous genotype contains two different alleles for a given gene, typically represented by one capital letter and one lowercase letter, like 'Tt'. The answer defines the genotypes as follows: Ss is heterozygous (C), SS is homozygous dominant (A), and ss is homozygous recessive (B). These terms describe the presence of dominant and recessive alleles in an individual's genetic makeup. Each genotype influences the traits expressed in the organism. The word genotypes is in reference to the alleles an individual receives at fertilization. Lets say that the allele/gene/trait, genotype for the Tall plant is T and dominate and the allele/gene.