If allele T (long tongue) exhibits incomplete dominance over the recessive allele t (short tongue), a heterozygote would most likely have a tongue length intermediate between long and short.

In this case, the allele for long tongue (T) is incompletely dominant over the allele for short tongue (t). That means if an individual has one copy of the dominant allele (T) and one copy of the recessive allele (t), the resulting phenotype will be an intermediate trait—a tongue length that is not as long as the homozygous dominant TT (long tongue) individual, but longer than the homozygous recessive tt (short tongue) individual.

So, if we represent the heterozygote as Tt, this individual would most likely have a tongue length that is somewhere between long and short. The exact length, however, can differ between individual organisms due to other genetic factors and environmental influences, but the general trend is an intermediate phenotype compared to the two homozygous conditions.

Extra: In genetics, when we talk about dominance, we're usually referring to the relationship between alleles, which are different versions of a gene. In complete dominance, which you might be more familiar with, the presence of one dominant allele (like T for long tongue) is enough to completely mask the effect of a recessive allele (like t for short tongue) when paired together in a heterozygous organism (Tt).

However, in incomplete dominance, the situation is different. Neither allele is completely dominant over the other. Instead, the heterozygous phenotype is distinctly different from both homozygous phenotypes (TT and tt)—usually evidencing a blend or an intermediate state.

Dominance is a key concept in understanding how traits are passed from parents to offspring. It explains why sometimes you can see a blend of parental traits in their children, rather than one trait completely overshadowing the other. This type of genetic inheritance is important in many aspects of biology, including evolution and selective breeding, where the complex interplay of different alleles determines the characteristics of individuals within a population.