What defines a dominant trait?

A dominant trait is defined as one that manifests in an organism's phenotype, or observable characteristics, even when it is paired with a recessive trait. This means that if an individual has at least one allele for the dominant trait, that trait will be expressed. For example, in the case of flower color, if purple is a dominant trait and white is recessive, a plant with one purple allele and one white allele will still produce purple flowers. This characteristic underscores the fundamental principles of Mendelian genetics, where certain alleles can overshadow the influence of others.

The other options do not accurately capture the definition of a dominant trait. A trait that only appears when associated with recessive traits does not align with the idea of dominance; instead, it describes a recessive trait. Similarly, a trait influenced solely by environmental factors does not pertain to genetic inheritance or dominance. Lastly, a trait that cannot be inherited represents a misunderstanding of genetics, as dominant traits are specifically defined by their inheritance patterns. Understanding how dominant traits function helps in grasping the complexities of genetic variation and inheritance.