Humber Admissions Practice Test

Which term describes an organism's physical appearance or visible traits?

1. Genotype

2. Phenotype

3. Allele

4. Dominant allele

The correct answer is: Phenotype

The term that describes an organism's physical appearance or visible traits is phenotype. This encompasses all observable characteristics such as color, size, shape, and other traits that can be identified and measured. It reflects the expression of the organism's genetic makeup (genotype) in the context of its environment. For instance, if a plant's genotype includes genes for tall stature and green leaves, the actual height and color of the leaves that you observe would be its phenotype. This concept is crucial in genetics, as it helps illustrate how genes express themselves in the form of traits that are evident in an organism. In contrast, the genotype refers to the genetic constitution of an organism—not the physical attributes. Alleles are the different forms of a gene, while a dominant allele is one that can overshadow the expression of a recessive allele. However, neither of these terms directly addresses the visible traits of an organism, making phenotype the accurate choice in this context.