What aspect of genetics involves traits that can be observed physically?

The concept of phenotype refers to the observable physical characteristics of an organism that result from the interaction between its genetic makeup and environmental factors. This includes traits such as height, eye color, and the presence of certain physical abilities. The phenotype is what we see in an individual, as opposed to the genotype, which is the underlying genetic code that determines those traits.

For instance, two individuals may share the same genotype but may express different phenotypes due to environmental influences or variations in gene expression. Therefore, when discussing observable traits, phenotype is the correct term, as it encapsulates the physical manifestations of genetic information.