What is the term for the observable traits of an organism?

The observable traits of an organism are referred to as the phenotype. The phenotype encompasses all the characteristics that can be seen or measured, such as physical appearance, development, and behavior. These traits result from the interaction between an organism's genotype, which is its genetic makeup, and the environment it exists in.

For example, in a plant, the phenotype may include attributes like flower color, height, and leaf shape, all of which can be directly observed and measured. This term is essential in understanding how specific genetic variations may manifest as distinct physical traits in various organisms.

The other terms presented in the question refer to different concepts in genetics. Genotype pertains to the genetic constitution of an organism, specifically the alleles present. Alleles are different forms of a gene that can lead to variations in traits. Karyotype refers to the number and appearance of chromosomes in the nucleus of a cell. Understanding these distinctions helps clarify the various aspects of genetics and inheritance.