NCEA Level 2 Biology Genetics Practice Exam 2025 – The Complete All-in-One Guide for Exam Success!

A dominant genotype is characterized by the presence of at least one dominant allele in the organism's genotype. In this context, the letter 'T' represents a dominant allele, while the letter 't' represents a recessive allele.

When examining the provided genotypes:

- The genotype TT is homozygous dominant, meaning it carries two copies of the dominant allele. This genotype will express the dominant trait.

- The genotype Tt is heterozygous, containing one dominant allele and one recessive allele. The presence of the dominant allele ensures that this genotype will also express the dominant trait.

Both of these genotypes (TT and Tt) will result in the expression of the dominant trait, which is why the choice that includes both options is correct. In contrast, the recessive genotype tt does not express the dominant trait, as it lacks any dominant alleles. This illustrates that both TT and Tt can express the dominant phenotype, confirming that the answer encapsulating both options successfully identifies the presence of dominant genotypes.