The observable characteristics of an organism are called its

• A. Genotype
• B. Phenotype
• C. Locus
• D. Allele

Answer: (B)

Observable traits are called the phenotype. The phenotype is what you can see or measure in an organism—things like height, eye or leaf color, and shape. These traits arise from how the organism’s genes are expressed (the genotype) and can be influenced by the environment, so the same genetic makeup can lead to different phenotypes in different conditions. The genotype refers to the genetic constitution, the specific alleles an individual carries. A locus is simply the exact position of a gene on a chromosome, and an allele is a variant form of that gene. Together, the genetic information and its expression, shaped by the environment, produce the observable phenotype.