The phenotype for smooth pod has two genotypes that is SS (homozygous) and Ss (Heterozygous). The genotype is the set of genes in our DNA which is responsible for a particular trait. The phenotype is the physical expression, or characteristics, of that trait. The dominant allele for smooth pod shape in peas is S. The recessive allele for constricted pod shape is s, therefore the heterozygous for smooth pod will be Ss.