Final answer:
An organism's traits are determined by the genes it inherits, with different combinations resulting in varying traits. These traits are part of the organism's phenotype, which describes the observable characteristics resulting from gene expression.
Step-by-step explanation:
An organism's traits are determined by the specific combination of inherited genes. These genes are the discrete areas on the DNA that contain the instructions for making the RNA and protein molecules necessary for all life processes. Traits, such as hair color, can vary from blonde to brown or black because of the differences in genes inherited from both parents. Even small changes in a gene's nucleotide sequence can lead to different traits.
The observable traits expressed by an organism, such as height, skin color, or build, are described as its phenotype. This phenotype results from the specific genes that are actively being used to make proteins at any given time, reflecting the individual's genetic makeup.