What should be filled in as the parent's alleles in a Punnett square?

In a Punnett square, the alleles of the parents are represented along the top and side of the square. The choice of Gg reflects a heterozygous genotype, where one allele is dominant (G) and one is recessive (g). This representation is crucial when considering traits that follow Mendelian inheritance patterns, as it allows for the prediction of the genotypic and phenotypic ratios in the offspring based on the combinations of these alleles.

Using Gg as the alleles in the Punnett square indicates that one parent has one dominant and one recessive allele, which is common in genetic crosses. This setup permits the analysis of inheritance patterns and the probability of various traits appearing in the offspring. In contrast, the other options (HH, Aa, Tt) also represent valid genotypes for different scenarios, but Gg aligns with a key aspect of demonstrating variation in breeding and the potential outcomes when looking at a single gene inheritance. Thus, using Gg provides a clear illustration of how traits may be passed down based on parental allele combinations in genetics.