What term describes the observable characteristics of an organism?

• A. Genotype
• B. Phenotype
• C. Allele
• D. Genetic marker

Answer: (B)

The observable characteristics of an organism are referred to as the phenotype. This term encompasses all the physical traits and attributes that can be seen or measured, such as height, color, shape, and behavior. The phenotype is influenced by the organism's genotype, which is the genetic makeup or the specific alleles present in the organism. Additionally, environmental factors can also impact the phenotype, highlighting the interaction between genetics and the environment. The concept of phenotype is crucial in genetics, as it allows researchers to study how specific genotypes manifest as visible traits.

In contrast, the term genotype relates specifically to the genetic constitution of the organism and does not encompass the observable traits. An allele represents one of the possible forms of a gene and plays a role in determining the genotype. A genetic marker is a specific DNA sequence that can be used to identify a particular location on a chromosome but does not directly refer to an observable characteristic. Therefore, phenotype is the correct and most comprehensive term for describing the observable traits of an organism.